Commercial Water Heaters
Neutrality remake campaign: from-scratch field derivation per authoring cheatsheet; project parameters and derived dispositions
Showing changes from Rev 4
to Rev 5
in Commercial Water Heaters.
−---
−title: Commercial Water Heaters
−category: Plumbing
−toc_depth: 3
−description: >
− When to use: Commercial domestic-hot-water (DHW) generation equipment serving commercial, institutional, and industrial buildings. Covers storage gas-fired water heaters (atmospheric, power-vented, power-direct-vented, and condensing), commercial electric storage water heaters, instantaneous and tankless gas water heaters (including condensing), heat-pump water heaters (HPWH), indirect-fired storage tanks heated by a boiler heat exchanger or by solar / waste-heat sources, and semi-instantaneous packaged units. Includes storage tanks (glass-lined, stainless, cement-lined), thermal expansion tanks, ASSE 1017 master mixing valves and ASSE 1070 point-of-use temperature-limiting devices, recirculation pumps and the circulating system, ASHRAE 188 Legionella requirements (storage and distribution setpoints, mixing-valve setpoints), and the venting, fuel-gas connection, condensate drain, electrical, and seismic provisions associated with the water-heating equipment itself.
−
− Not intended for: Domestic water piping upstream and downstream of the equipment (see [[sync/domestic-water-piping]]); the plumbing fixtures served (see [[sync/plumbing-fixtures]]); sanitary-waste and vent piping for tank, T&P relief, and condensate routing to drain (see [[sync/sanitary-waste-and-vent-piping]]); building water-service backflow prevention assemblies (see [[sync/backflow-prevention]]); solar thermal collectors and solar array piping (separate scope; indirect-fired storage tanks heated by a solar loop are within this scope but the collector array is not); hydronic-heating boilers serving space-heating loops (those serve the building-heating system, not DHW — see [[sync/hydronic-piping]] for the boiler-side hydronic piping, with indirect DHW tank coil connections covered here); pool and spa water heating; process and industrial hot water generation above standard DHW temperatures; steam-to-water DHW heat exchangers in central steam plants (a related but distinct equipment category).
−---
−
−# Scope {toc}
−
−## This standard covers the equipment, accessories, controls, vent and combustion-air system, fuel-gas piping connection, electrical connection, condensate handling, seismic restraint, installation, startup, and testing of commercial domestic-hot-water generating equipment. {note}
−## The scope of this standard begins at the cold-water inlet connection to the water heater or storage tank and terminates at the hot-water and recirculation-return outlet connections downstream of the master mixing valve. {note}
−## The domestic-water piping that conveys water to and from this equipment is the subject of [[sync/domestic-water-piping]]. {note}
−
−## Equipment selection, capacity, redundancy, location, and the recirculation-system layout are [[drawing: as indicated on the plumbing equipment schedules, mechanical room plans, and water heater piping diagrams]]. {note}
−## This standard establishes the materials, performance, controls, and installation requirements that govern those drawings. {note}
−
−## All wetted components in contact with potable water shall comply with NSF/ANSI 61 for health effects and NSF/ANSI/CAN 372 for lead-free content (0.25 percent maximum weighted average lead content of wetted surface area), a federal requirement under the Safe Drinking Water Act applicable to all plumbing components installed on or after January 4, 2014.
−
−## This standard establishes the equipment-level temperature, mixing-valve, and recirculation requirements necessary to support the project's Water Management Program.
−
−## Building-wide Legionella management is the subject of a project-specific Water Management Program developed in accordance with ASHRAE 188 by the Owner's design team and operations staff; this standard does not constitute the program itself. {note}
−
−# Referenced Standards {toc}
−
−## Equipment, components, and installation shall comply with the latest adopted edition of the following standards and codes.
−
−| Standard | Title |
−|----------|-------|
−| ASHRAE 188 | Legionellosis: Risk Management for Building Water Systems |
−| ASHRAE 90.1 | Energy Standard for Sites and Buildings Except Low-Rise Residential Buildings (water heater efficiency, pipe insulation, recirculation controls) |
−| ASHRAE 90.2 | Energy-Efficient Design of Low-Rise Residential Buildings (referenced where residential-style equipment is installed in commercial small projects) |
−| ASHRAE 62.1 | Ventilation and Acceptable Indoor Air Quality (combustion-air and mechanical-room ventilation) |
−| IECC | International Energy Conservation Code (commercial provisions referencing ASHRAE 90.1) |
−| 10 CFR Part 431 | DOE Energy Conservation Standards for Commercial Water Heaters (thermal efficiency, standby loss) |
−| 10 CFR Part 430 | DOE Energy Conservation Standards for Consumer Water Heaters (UEF — applies to residential-grade units) |
−| ANSI Z21.10.1 / CSA 4.1 | Gas Water Heaters — Volume I, Storage Water Heaters with Input Ratings of 75,000 Btu/h and Under |
−| ANSI Z21.10.3 / CSA 4.3 | Gas-Fired Water Heaters for Storage and Instantaneous Water Heaters (commercial; inputs above 75,000 Btu/h, and circulating and instantaneous types) |
−| UL 174 | Household Electric Storage Tank Water Heaters |
−| UL 1453 | Electric Booster and Commercial Storage Tank Water Heaters |
−| UL 1995 / CSA C22.2 No. 236 | Heating and Cooling Equipment (referenced for HPWH packaged units, superseded for new HPWHs by UL 60335-2-40) |
−| UL 60335-2-40 / CSA C22.2 No. 60335-2-40 | Household and Similar Electrical Appliances — Safety — Particular Requirements for Electrical Heat Pumps, Air-Conditioners and Dehumidifiers |
−| ASME Boiler and Pressure Vessel Code, Section VIII Division 1 | Rules for Construction of Pressure Vessels (tanks exceeding the commercial threshold) |
−| ASME CSD-1 | Controls and Safety Devices for Automatically Fired Boilers (where applicable to high-input water heaters) |
−| NSF/ANSI 5 | Water Heaters, Hot Water Supply Boilers, and Heat Recovery Equipment (commercial food service and hygiene-sensitive applications) |
−| NSF/ANSI 61 | Drinking Water System Components — Health Effects |
−| NSF/ANSI/CAN 372 | Drinking Water System Components — Lead Content |
−| ASSE 1003 | Performance Requirements for Water Pressure Reducing Valves (referenced for upstream PRV coordination) |
−| ASSE 1017 | Performance Requirements for Temperature Actuated Mixing Valves for Hot Water Distribution Systems (master mixing valve) |
−| ASSE 1070 / ASME A112.1070 / CSA B125.70 | Performance Requirements for Water Temperature Limiting Devices (point-of-use thermostatic) |
−| ASSE 1082 | Performance Requirements for Water Heaters with Integral Temperature Limiting Capability |
−| ANSI Z21.22 / CSA 4.4 | Relief Valves for Hot Water Supply Systems (T&P relief valves) |
−| NFPA 54 / ANSI Z223.1 | National Fuel Gas Code |
−| IFGC | International Fuel Gas Code |
−| NFPA 70 | National Electrical Code |
−| NFPA 31 | Standard for the Installation of Oil-Burning Equipment (where oil-fired) |
−| UL 1738 | Venting Systems for Gas-Burning Appliances, Categories II, III, and IV |
−| UL 103 | Factory-Built Chimneys for Residential Type and Building Heating Appliances (Type B and L vent) |
−| UL 174 | Household Electric Storage Tank Water Heaters |
−| AGA / CSA NGV-1 | Compressed Natural Gas Vehicle Fueling Connection Devices (referenced for fuel-gas connection components where applicable) |
−| ASME A112.4.1 | Water Heater Relief Valve Drain Tubes |
−| ASCE 7 | Minimum Design Loads and Associated Criteria for Buildings and Other Structures (seismic restraint) |
−| OSHPD / IAPMO listings | Pre-approved seismic anchorage details for water heaters in high-seismic jurisdictions |
−| IPC | International Plumbing Code |
−| UPC | Uniform Plumbing Code |
−
−## Where the contract documents, the Authority Having Jurisdiction (AHJ), or a referenced standard impose conflicting requirements, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
−
−## The applicable plumbing code (IPC or UPC as adopted by the jurisdiction), the applicable mechanical code, and the applicable fuel-gas code (NFPA 54 / IFGC) shall take precedence over all other references on any matter directly addressed by those codes.
−
−# Submittals {toc}
−
−## Action Submittals {toc}
−
−### Contractor shall submit the following for the Engineer's review prior to procurement and installation.
−### Work shall not proceed on any water-heating equipment until the corresponding submittals have been reviewed and returned.
−
−- Product data for each water heater, indicating the manufacturer's model number, fuel type, input rating (Btu/h or kW), storage volume, recovery rate at the specified temperature rise, first-hour rating where applicable, thermal efficiency or UEF, vent category (I, II, III, or IV), permitted vent materials and maximum vent length, electrical characteristics, gas-train pressure range, applicable certification listings (ANSI Z21.10.3, UL 1453, UL 60335-2-40, or other as appropriate), and NSF/ANSI 5 listing where required by the application
−- Product data for storage tanks (indirect-fired, ASME, or supplemental), including tank material and lining (glass-lined, stainless steel Type 316L, cement-lined), insulation R-value, working pressure, T&P relief connection size, anode rod type and replacement access, and applicable certification (ASME Section VIII Div 1 stamp where required, NSF/ANSI 61)
−- Product data for the master mixing valve (ASSE 1017), including body material, paired hot/cold/blend connection sizes, minimum and maximum flow rate at the specified pressure drop, setpoint adjustment range, accuracy, integral isolation and check valves, and union or flanged service connections
−- Product data for any point-of-use temperature-limiting devices (ASSE 1070) coordinated with [[sync/plumbing-fixtures]]
−- Product data for the thermal expansion tank, including pre-charge pressure, acceptance volume, total volume, diaphragm or bladder material (potable PE-X lined or butyl), and NSF/ANSI 61 certification for wetted parts
−- Product data for the hot-water recirculation pump, including flow rate, head, motor data, wetted materials (bronze or stainless steel), NSF/ANSI 61 certification, and control type (time clock, aquastat, demand, or combination)
−- Product data for the T&P relief valve per ANSI Z21.22, including set pressure, set temperature, discharge capacity (Btu/h), and connection size; provide separate documentation for tank T&P relief and any heat-exchanger or system relief valves
−- Combustion-air and venting plan for each gas-fired heater, including vent category, vent material and diameter, total equivalent vent length, termination location and clearances, common venting calculations where multiple heaters share a vent, and condensate drain routing for Category IV (condensing) equipment
−- Fuel-gas connection details, including supply pressure at the heater, gas-train components (manual shutoff, sediment trap / dirt leg, union, regulator if required), pipe sizing verification, and CSST or rigid-pipe details
−- Electrical connection details, including circuit ampacity, overcurrent protection size, disconnect location and rating, equipment grounding and bonding (coordinate with [[sync/grounding-and-bonding]] for electric units), and integration with the building energy-management system or BAS (coordinate with [[sync/building-automation-system]])
−- Heat-pump water heater submittals shall additionally include heating capacity at design ambient conditions, COP at AHRI rating conditions, sound level (sones or dBA at specified distance), refrigerant type and charge, condensate generation rate, and any space cooling or dehumidification effect on the mechanical room
−- Seismic anchorage calculations or pre-approved seismic anchorage details (OSHPD, IAPMO, or equivalent) where required by the project's Seismic Design Category
−- Startup and commissioning checklist and the manufacturer's installation and operation manuals
−- Schematic piping diagram showing the heater(s), storage tanks, mixing valves, expansion tank, recirculation pump and balancing valves, isolation valves, gauges, thermometers, drain valves, and union connections, with valve tags assigned and a flow path traceable through the diagram
−
−```datasheet
−label: Action Submittals Required
−type: checkbox
−options:
− - "Water heater product data with input, recovery, efficiency, vent category"
− - "Storage tank product data with lining, insulation, ASME stamp where required"
− - "Master mixing valve product data (ASSE 1017)"
− - "Point-of-use temperature-limiting device product data (ASSE 1070)"
− - "Thermal expansion tank product data (NSF 61 wetted parts)"
− - "Recirculation pump product data (NSF 61 wetted parts)"
− - "T&P relief valve product data (ANSI Z21.22)"
− - "Combustion-air and venting plan"
− - "Fuel-gas connection details"
− - "Electrical connection details"
− - "HPWH-specific submittals (heating capacity, COP, sound, refrigerant)"
− - "Seismic anchorage calculations or pre-approved details"
− - "Startup / commissioning checklist and O&M manuals"
− - "Schematic piping diagram with valve tagging"
−default: "Water heater product data with input, recovery, efficiency, vent category"
−```
−
−## Closeout Submittals {toc}
−
−### Contractor shall provide the following at substantial completion before the water-heating system is accepted.
−
−- As-built piping schematic showing actual installed configuration, valve tag locations, gauge and thermometer locations, drain valve locations, and the final routing of vent, gas, electrical, and condensate connections
−- Operation and maintenance (O&M) manuals for the water heater, storage tank, mixing valve, expansion tank, recirculation pump, T&P relief valve, controls, and any auxiliary equipment, with the manufacturer's recommended maintenance intervals tabulated
−- Manufacturer's startup report signed by the manufacturer's authorized service representative or by a technician trained and certified by the manufacturer, indicating that combustion, water-side, and electrical systems were verified per the manufacturer's commissioning procedure
−- Combustion test reports for each gas-fired heater, recording fuel-gas supply pressure (static and dynamic), manifold pressure, CO and CO₂ in the flue gas, stack temperature, and combustion efficiency at high-fire and (where modulating or staged) at the lowest stable fire rate
−- Field test reports for water-side performance — measured recovery rate, measured outlet temperature at the heater, measured outlet temperature downstream of the master mixing valve, measured recirculation return temperature at the heater inlet, and verification that the T&P relief valve and any energy cut-out controls function as specified
−- Water Management Program documentation interface — recorded equipment setpoints, recirculation control schedule, and any operational logs required by the Owner's ASHRAE 188 program
−- Warranty documentation for the water heater, the storage tank, the heat exchanger or anode rod (where covered separately), and all auxiliary equipment
−
−```datasheet
−label: Closeout Submittals Required
−type: checkbox
−options:
− - "As-built piping schematic with valve tag, gauge, thermometer, and drain locations"
− - "Operation and maintenance (O&M) manuals with maintenance intervals tabulated"
− - "Manufacturer's signed startup report"
− - "Combustion test reports for each gas-fired heater"
− - "Field test reports for water-side performance"
− - "Water Management Program documentation interface (setpoints, schedule, logs)"
− - "Warranty documentation for heater, tank, heat exchanger/anode, and auxiliaries"
−default: "As-built piping schematic with valve tag, gauge, thermometer, and drain locations"
−```
−
−### The Contractor shall provide the closeout submittals listed above at substantial completion before the water-heating system is accepted.
−
−# Quality Assurance {toc}
−
−## Installer Qualifications {toc}
−
−### Water-heating equipment installation shall be performed by personnel licensed in the trade or trades that apply to the equipment installed — plumbing license for water-side piping, mechanical license for venting, fuel-gas license where required by the AHJ for fuel-gas connection, and electrical license for the electrical connection.
−
−### Where the manufacturer requires a factory-authorized startup, startup and initial commissioning shall be performed by a technician currently certified by the equipment manufacturer.
−
−### The Contractor shall furnish documentation of current manufacturer certification before startup begins.
−
−### Refrigerant-containing heat-pump water heaters with refrigerant quantities at or above the EPA Section 608 threshold (currently 5 lb for most HFC charges) shall be installed and serviced only by EPA 608-certified technicians.
−
−### The Contractor shall maintain EPA 608 certification documentation on site.
−
−## Product Listing and Certification {toc}
−
−### Each water heater shall bear the certification mark of a Nationally Recognized Testing Laboratory (NRTL) recognized by OSHA for the applicable product standard — typically ANSI Z21.10.3 / CSA 4.3 for commercial gas, UL 174 or UL 1453 for electric, and UL 60335-2-40 for HPWH.
−
−### Storage tanks for which ASME Section VIII Division 1 construction is required shall bear the ASME "U" or "UM" stamp.
−
−### Where the application requires NSF/ANSI 5 listing (commercial food service, healthcare hot-water washing systems, and similar hygiene-sensitive applications), the equipment shall bear the NSF/ANSI 5 listing mark.
−
−## ASME Pressure Vessel Thresholds {toc}
−
−### A water-heating vessel is considered a "pressure vessel" subject to ASME Boiler and Pressure Vessel Code Section VIII Division 1 construction and stamping requirements when any one of the threshold criteria below is exceeded. {note}
−
−### Equipment is subject to ASME Section VIII Division 1 construction and stamping when storage volume exceeds 120 gal, input rating exceeds 200,000 Btu/h, working pressure exceeds 160 psi, or operating temperature exceeds 210°F.
−
−### Equipment selected at or above any ASME threshold shall be ASME-stamped, and the certification documentation shall be included in the closeout submittals.
−
−### The Engineer shall not specify equipment that exceeds an ASME threshold by a small margin in order to avoid the requirement; ASME construction is appropriate at and above these thresholds and shall be procured accordingly.
−
−## Lead-Free Compliance {toc}
−
−### All wetted components — heater inlet/outlet fittings, dip tubes, tappings, drain valves, T&P relief valve wetted parts, anode rod connections, mixing valve, expansion tank diaphragm or bladder, recirculation pump wetted parts, gauges, and unions — shall be certified to NSF/ANSI/CAN 372, confirming that the weighted average lead content of the wetted surface area does not exceed 0.25 percent.
−
−### This NSF/ANSI/CAN 372 lead-content requirement is a federal requirement under the Reduction of Lead in Drinking Water Act and is not subject to project-level waiver.
−
−## Manufacturer Authorization {toc}
−
−### Equipment shall be procured through a manufacturer-authorized distributor or representative.
−
−### The Owner shall not be required to engage a non-authorized rebuilder, refurbisher, or third party for warranty service during the warranty period.
−
−### The Contractor shall furnish the local authorized service representative's contact information in the O&M manuals.
−
−# Environmental and Service Conditions {toc}
−
−## Installation Environment {toc}
−
−### Water heaters shall be located in a conditioned mechanical space sized to provide combustion air, ventilation, equipment service clearance, and seismic anchorage as required by the equipment listing and by NFPA 54 / IFGC for fuel-fired equipment.
−
−```datasheet
−label: Mechanical Room Floor Drain
−type: radio
−options:
− - "Yes — floor drain provided in mechanical room"
− - "No — indirect waste receptor or condensate sump provided"
−default: "Yes — floor drain provided in mechanical room"
−```
−
−### The mechanical space shall not be subject to freezing temperatures during normal building operation; freeze protection shall be provided where freezing is possible, particularly for condensing equipment with condensate piping.
−
−### The mechanical space shall have a floor drain capable of accepting the maximum flow of the T&P relief valve discharge, condensate discharge, and tank drain-down without flooding adjacent areas.
−
−### Where a floor drain is not available, an indirect-waste receptor or an alarmed and pumped condensate-collection sump shall be provided.
−
−### The mechanical space serving a heat-pump water heater shall be sized and ventilated to allow the HPWH to operate without driving space temperature below the manufacturer's minimum operating ambient temperature.
−
−### Where the heat-pump cooling effect would over-cool the mechanical space during the cooling season, ductwork shall be installed to draw air from a thermally suitable source and return it to a location that does not adversely affect adjacent occupied spaces.
−
−## Combustion Air {toc}
−
−### Fuel-fired water heaters require combustion air at a rate determined by the input rating of the heater and the venting category. {note}
−
−### The combustion air source shall be specified for each fuel-fired water heater, consistent with its input rating and venting category, or designated not applicable for electric or heat-pump units.
−
−```datasheet
−label: Combustion Air Source
−type: select
−options:
− - "Direct-vent (sealed combustion) — concentric or parallel pipe from outside"
− - "Power-vent with indoor combustion air per NFPA 54 openings"
− - "Atmospheric / natural-draft with indoor combustion air per NFPA 54 openings"
− - "Engineered combustion-air duct with interlocked supply fan"
− - "Not applicable — electric or heat-pump (no combustion)"
−default: "Direct-vent (sealed combustion) — concentric or parallel pipe from outside"
−```
−
−### For Category I and II atmospheric and natural-draft heaters, combustion air shall be supplied per NFPA 54 / IFGC by openings communicating with the outside, by an engineered combustion-air duct, or by an interlocked mechanical combustion-air system.
−
−### For Category III and IV power-vented and direct-vented heaters, combustion air shall be drawn through a sealed combustion-air pipe terminated outside the building in accordance with the manufacturer's vent termination requirements.
−
−## Service Clearances {toc}
−
−### Service clearances shall meet or exceed the manufacturer's published minimums and the working clearances required by NFPA 70 for the electrical disconnect.
−
−### Tank-type heaters shall provide overhead access for anode rod replacement equal to the rod length plus a working margin (typically 36 in. above the tank for full-length rods, or as published by the manufacturer for flexible / segmented rods).
−
−### Direct-vent terminations shall meet the manufacturer's clearance to building openings, soffits, grade, snow line, and adjacent terminations.
−
−## Water Quality {toc}
−
−### Domestic-water inlet water quality affects the service life of all wetted components, particularly anode rods, glass-lined tank linings, and brazed-plate heat exchangers in indirect-fired equipment. {note}
−
−### Where the inlet water hardness exceeds 7 grains per gallon (gpg), softening or scale-control treatment shall be evaluated by the Engineer.
−
−```datasheet
−label: Inlet Water Treatment
−type: select
−options:
− - "None — municipal supply within manufacturer's acceptable range"
− - "Water softener upstream of cold-water inlet"
− - "Scale-control system (template-assisted crystallization or equivalent)"
− - "Engineered treatment per project water analysis"
−default: "None — municipal supply within manufacturer's acceptable range"
−```
−
−### Where the chloride level exceeds 100 mg/L or the water is supplied by an on-site well of unknown chemistry, the tank lining material shall be selected for the water chemistry (stainless steel 316L for high chlorides; glass-lined for typical municipal supply; cement-lined for very large indirect tanks).
−
−### The Contractor shall not be responsible for premature equipment failure caused by water chemistry outside the manufacturer's published acceptable range, provided the equipment was installed and started up correctly.
−
−# Water Heater Selection {toc}
−
−## General Selection Criteria {toc}
−
−### Water heater type shall be selected to suit the building's hot-water load profile (peak, recovery, and standby), the available utility services (gas service pressure and electric service capacity), the climate (which affects HPWH performance and condensate management), the available mechanical room space, the noise sensitivity of adjacent spaces, the redundancy requirement, and the project's energy and emissions goals.
−
−```datasheet
−label: Water Heater Type
−type: radio
−options:
− - "Gas-fired storage — atmospheric (Category I)"
− - "Gas-fired storage — power-vented (Category III)"
− - "Gas-fired storage — power direct-vented (Category III, sealed combustion)"
− - "Gas-fired storage — condensing (Category IV)"
− - "Electric storage — commercial (UL 1453)"
− - "Gas-fired instantaneous / tankless — condensing"
− - "Gas-fired instantaneous / tankless — non-condensing"
− - "Heat-pump water heater (HPWH)"
− - "Indirect-fired storage tank — heated by external boiler"
− - "Indirect-fired storage tank — heated by solar / waste-heat source"
− - "Semi-instantaneous packaged water heater"
−default: "Gas-fired storage — condensing (Category IV)"
−```
−
−### The Engineer shall size the equipment based on the calculated hot-water demand using ASHRAE Handbook procedures or an equivalent recognized method; this standard establishes the equipment performance requirements that govern after the selection is made.
−
−### Storage gas-fired heaters are the established standard for commercial DHW in buildings with significant peak-to-average load ratios, and instantaneous (tankless) gas heaters minimize standby loss and footprint and are well suited to applications with steady moderate load or to point-of-use service. {note}
−
−### Heat-pump water heaters offer high efficiency (COP typically 2 to 4) and electrification but require careful mechanical-room sizing and condensate management. {note}
−
−### Indirect-fired storage tanks are appropriate where a boiler plant already exists for space heating, deferring the boiler's summer shutdown and providing a domestic-water load, and semi-instantaneous packaged units integrate a small buffer tank with a tankless heat exchanger to provide stable outlet temperature with limited standby loss. {note}
−
−## Input Rating {toc}
−
−### Input rating shall be sized by the Engineer to satisfy the peak hot-water demand in combination with the storage volume.
−### The input rating governs the recovery capacity and the standby losses of the equipment. {note}
−
−### The input rating shall be [[drawing: as indicated on the water heater schedule]]; the datasheet establishes the typical input rating ranges, and the Engineer's calculation governs the actual selected value.
−
−```datasheet
−label: Heater Input Rating — Gas
−type: range
−unit: Btu/h
−drawing_ref: true
−options:
− min: 75000
− max: 4000000
− setpoints: [75000, 100000, 199000, 300000, 500000, 750000, 1000000, 1500000, 2000000, 3000000, 4000000]
−default: 500000
−```
−
−```datasheet
−label: Heater Input Rating — Electric
−type: range
−unit: kW
−drawing_ref: true
−options:
− min: 6
− max: 180
− setpoints: [6, 9, 12, 18, 24, 36, 54, 72, 90, 120, 150, 180]
−default: 36
−```
−
−## Recovery Capacity {toc}
−
−### Recovery capacity shall be expressed at a standard temperature rise (ΔT) and shall be sufficient, in combination with the storage volume, to satisfy the peak draw without exceeding the allowable temperature drop at the most remote fixture.
−
−```datasheet
−label: Recovery at 100°F ΔT
−type: range
−unit: GPH
−drawing_ref: true
−options:
− min: 30
− max: 5000
− setpoints: [30, 50, 100, 200, 350, 500, 750, 1000, 1500, 2000, 3000, 5000]
−default: 500
−```
−
−### Recovery at 100°F rise is the standard reference condition for commercial gas-fired equipment in the U.S. market; recovery at the project-specific design ΔT shall be confirmed against the equipment manufacturer's published performance curves.
−
−## Storage Volume {toc}
−
−### Storage volume shall be sized to absorb the difference between peak demand and recovery capacity, with a margin sufficient to maintain delivery temperature at the most remote fixture during the design draw.
−
−```datasheet
−label: Storage Volume
−type: range
−unit: gal
−drawing_ref: true
−options:
− min: 0
− max: 5000
− setpoints: [0, 6, 19, 40, 50, 75, 80, 100, 119, 120, 175, 250, 350, 500, 750, 1000, 1500, 2500, 5000]
−default: 119
−```
−
−### Increasing the storage volume reduces the required input rating; the Engineer shall optimize the storage-to-input ratio based on the load profile, the energy cost, the available space, and ASME-threshold considerations.
−
−### Tank-type heaters and supplemental storage tanks at 119 gal nominal and below are commonly selected to remain below the 120-gal ASME threshold; this is a legitimate design choice but shall not be used as a reason to under-size storage where the load profile genuinely calls for a larger tank.
−
−### Tanks at 120 gal nominal and above shall be ASME-stamped per the threshold criteria in this standard.
−
−## Efficiency {toc}
−
−### All water heaters shall meet or exceed the applicable minimum efficiency requirement under ASHRAE 90.1, the IECC, and the DOE Energy Conservation Standards (10 CFR Part 431 for commercial; 10 CFR Part 430 for residential-grade units installed in commercial small projects).
−
−```datasheet
−label: Minimum Efficiency Basis
−type: select
−options:
− - "Uniform Energy Factor (UEF) per DOE 10 CFR Part 430 (residential-grade)"
− - "Thermal Efficiency (Et) and Standby Loss (SL) per DOE 10 CFR Part 431 (commercial)"
− - "Coefficient of Performance (COP) at AHRI rating conditions (HPWH)"
−default: "Thermal Efficiency (Et) and Standby Loss (SL) per DOE 10 CFR Part 431 (commercial)"
−```
−
−```datasheet
−label: Minimum Thermal Efficiency — Gas-Fired (Et)
−type: range
−unit: "%"
−options:
− min: 80
− max: 99
− setpoints: [80, 82, 90, 92, 94, 95, 96, 97, 98, 99]
−default: 94
−```
−
−```datasheet
−label: Minimum UEF — Residential-Grade (where applicable)
−type: range
−unit: ""
−options:
− min: 0.60
− max: 4.00
− step: 0.01
−default: 0.81
−```
−
−```datasheet
−label: Minimum HPWH COP at AHRI Conditions (where applicable)
−type: range
−unit: ""
−options:
− min: 2.0
− max: 5.0
− step: 0.1
−default: 3.0
−```
−
−### Performance shall be reported as Uniform Energy Factor (UEF) for residential-grade equipment within DOE scope and as Thermal Efficiency (Et) and Standby Loss (SL) for commercial equipment within DOE scope.
−
−### The Engineer shall verify that the specified equipment satisfies the federal floor and any state or local energy-code-amended requirement.
−
−# Storage Tanks {toc}
−
−## Tank Construction and Lining {toc}
−
−### Storage tanks shall be selected with a lining material suitable for the inlet water chemistry, the operating temperature, and the service life expected for the application.
−
−```datasheet
−label: Storage Tank Lining
−type: select
−options:
− - "Glass-lined steel with sacrificial anode rod (standard)"
− - "Stainless steel Type 316L (no anode required)"
− - "Cement-lined steel (very large indirect tanks, raw water service)"
− - "Integral to packaged heater — manufacturer's standard lining"
−default: "Glass-lined steel with sacrificial anode rod (standard)"
−```
−
−### Glass-lined steel is the established standard for typical municipal water at storage temperatures up to 180°F; the porcelain-enamel lining is dependent on a functioning sacrificial anode rod for cathodic protection of the steel substrate at any small lining imperfection. {note}
−
−### Stainless steel Type 316L tanks eliminate the anode rod and tolerate higher chloride water chemistries, and are appropriate for water with chlorides above 100 mg/L, for installations where anode-rod maintenance is not feasible, and for hygiene-sensitive applications. {note}
−
−### Cement-lined tanks are used for very large indirect tanks and for raw or untreated water service, and rely on the cement lining's high pH to passivate the steel. {note}
−
−### Cement-lined tanks shall not be drained and left empty for extended periods, which causes the lining to dry and crack.
−
−## Anode Rod {toc}
−
−```datasheet
−label: Anode Rod Type
−type: select
−options:
− - "Magnesium — sacrificial (standard for municipal water)"
− - "Aluminum-zinc — sacrificial (where magnesium produces odor)"
− - "Powered impressed-current — non-sacrificial"
− - "Not applicable — stainless steel or cement-lined tank"
−default: "Magnesium — sacrificial (standard for municipal water)"
−```
−
−### Glass-lined tanks shall be provided with at least one sacrificial anode rod, accessible from the top of the tank, of magnesium, aluminum-zinc, or powered-impressed-current type.
−
−### Magnesium anodes are the standard for typical municipal water and provide strong cathodic protection at the cost of faster consumption and occasional sulfate-reducing-bacteria odor in low-flow installations; aluminum-zinc anodes are appropriate where magnesium produces "rotten egg" odor or where water hardness is low, and powered-impressed-current anode systems eliminate sacrificial-anode replacement at the cost of a powered control unit and are appropriate for inaccessible installations. {note}
−
−### Anode rods shall be accessible for inspection and replacement without disturbing the surrounding piping.
−
−### The Contractor shall confirm the overhead clearance required for the rod length and shall locate the tank accordingly.
−
−### Where overhead clearance is restricted, flexible or segmented anode rods rated by the manufacturer for the application shall be specified.
−
−## Tank Insulation {toc}
−
−```datasheet
−label: Tank Insulation
−type: select
−options:
− - "Factory insulated, R-value meeting ASHRAE 90.1 / DOE minimum"
− - "Factory insulated, R-value exceeding ASHRAE 90.1 by 25 percent or more"
− - "Field-applied supplemental insulation in addition to factory insulation"
−default: "Factory insulated, R-value meeting ASHRAE 90.1 / DOE minimum"
−```
−
−### Tanks shall be factory-insulated with rigid foam, fiberglass, or equivalent to satisfy the standby-loss requirement under DOE 10 CFR Part 431 and ASHRAE 90.1.
−
−### Field-applied insulation on the tank exterior is not a substitute for factory insulation.
−
−### Where the tank is located in an unconditioned space and the factory insulation is at the federal minimum, supplemental field-applied insulation per the Engineer's direction may be provided.
−
−## Indirect-Fired Tank Coil {toc}
−
−```datasheet
−label: Indirect Tank Coil Wall
−type: radio
−options:
− - "Single-wall coil — boiler loop contains water only (no glycol or chemicals)"
− - "Double-wall coil — boiler loop contains glycol or chemical treatment"
− - "Not applicable — not indirect-fired"
−default: "Not applicable — not indirect-fired"
−```
−
−### Indirect-fired storage tanks shall include an internal heat-exchanger coil sized for the design heating load at the boiler-supply temperature provided by the [[sync/hydronic-piping]] boiler loop.
−
−### The coil material shall be stainless steel or copper, sized for the boiler-side flow rate, and provided with a separate isolation valve and union on both supply and return connections to permit coil replacement.
−
−### The boiler loop and the domestic water in the tank shall be physically separated by the coil wall.
−
−### Double-wall construction shall be provided where the boiler loop contains glycol or chemical treatment, where required by code, or where the AHJ requires separation between potable water and a chemically treated fluid.
−
−# Venting and Combustion {toc}
−
−## Vent Category {toc}
−
−### Gas-fired water heaters are classified by venting category under ANSI Z21.10.3 and NFPA 54 by combustion-system pressure (positive or negative within the vent) and by the dew point of the flue gas (above or below). {note}
−
−### The vent category of each gas-fired water heater shall be specified in accordance with ANSI Z21.10.3 and NFPA 54, based on its combustion-system pressure and flue-gas dew point.
−
−```datasheet
−label: Vent Category
−type: select
−options:
− - "Category I — non-positive, non-condensing (atmospheric, Type B vent)"
− - "Category II — non-positive, condensing (uncommon)"
− - "Category III — positive, non-condensing (power-vented)"
− - "Category IV — positive, condensing"
− - "Not applicable — electric, HPWH, or indirect-fired"
−default: "Category IV — positive, condensing"
−```
−
−### Category I is non-positive vent pressure, non-condensing — typical atmospheric heaters using Type B vent; Category II is non-positive vent pressure, condensing — uncommon; Category III is positive vent pressure, non-condensing — power-vented non-condensing heaters using special vent material rated for positive pressure; Category IV is positive vent pressure, condensing — condensing heaters using AL29-4C stainless steel, polypropylene, or PVC/CPVC vent piping as listed by the manufacturer. {note}
−
−## Vent Material {toc}
−
−### Vent material shall be selected to match the equipment's vent category, to be listed by the equipment manufacturer for the specific model, and to comply with UL 1738 (Categories II, III, IV) or UL 103 (Type B and L vent for Category I).
−
−```datasheet
−label: Vent Material
−type: select
−options:
− - "Type B double-wall metal (Category I only)"
− - "AL29-4C stainless steel (Category III and IV)"
− - "Polypropylene — UL 1738 listed (Category III and IV)"
− - "PVC — manufacturer-listed and AHJ-accepted (Category IV only)"
− - "CPVC — manufacturer-listed and AHJ-accepted (Category IV only)"
− - "Not applicable — electric, HPWH, or indirect-fired"
−default: "AL29-4C stainless steel (Category III and IV)"
−```
−
−### PVC and CPVC vent material is permitted only where specifically listed by the equipment manufacturer and where allowed by the applicable code and AHJ.
−
−### AL29-4C stainless steel and listed polypropylene are the durable choices for Category IV vent and shall be specified where life-cycle, code, or AHJ considerations warrant.
−
−### Some jurisdictions and many model codes are moving away from PVC vent for gas-fired condensing appliances due to long-term durability and flue-gas temperature concerns. {note}
−
−## Vent Sizing and Termination {toc}
−
−### Vent diameter, total equivalent length, number and type of fittings, and termination clearances shall comply with the equipment manufacturer's installation instructions and with NFPA 54 / IFGC.
−
−### Termination location and configuration are [[drawing: as indicated on the venting plan and mechanical roof plan]].
−
−### Common venting of multiple appliances shall be sized using NFPA 54 vent tables or by an engineered sizing method published by the vent or appliance manufacturer.
−
−### Common venting of Category IV equipment from different manufacturers shall not be performed without each manufacturer's written approval of the proposed configuration.
−
−## Vent Configuration Selection {toc}
−
−```datasheet
−label: Venting Configuration
−type: radio
−options:
− - "Individually vented — one heater per vent"
− - "Common vented — multiple heaters of same manufacturer per NFPA 54"
− - "Direct-vent through wall — sealed combustion"
− - "Sidewall power vent — non-condensing"
−```
−
−## Condensate Drain (Category IV) {toc}
−
−### Category IV (condensing) heaters produce acidic condensate (typical pH 3 to 5) that shall be neutralized before discharge to a sanitary drain that may contain ferrous piping, copper piping, or building materials sensitive to acidic discharge.
−
−```datasheet
−label: Condensate Handling — Category IV
−type: select
−options:
− - "Neutralizer + gravity drain to indirect-waste receptor"
− - "Neutralizer + condensate pump to indirect-waste receptor"
− - "Neutralizer + gravity drain to floor drain"
− - "Not applicable — non-condensing equipment"
−default: "Neutralizer + gravity drain to indirect-waste receptor"
−```
−
−### The Contractor shall provide a manufacturer-listed or third-party condensate neutralizer with replaceable limestone or magnesium-oxide media, sized for the maximum condensate flow rate, and shall pipe the neutralizer discharge by gravity or by an approved condensate pump to an indirect-waste receptor or floor drain per the applicable plumbing code.
−
−### Condensate piping shall be of a material chemically resistant to low-pH condensate — PVC, CPVC, polypropylene, or stainless steel — and shall not be of bare copper, brass, or carbon steel.
−
−# Fuel-Gas Connection {toc}
−
−## Fuel-gas piping to the heater shall be sized and installed per NFPA 54 / IFGC and shall comply with [[sync/fuel-gas-piping]] where that standard exists in the library.
−
−```datasheet
−label: Fuel-Gas Service to Heater
−type: select
−options:
− - "Natural gas, low-pressure (≤ 0.5 psig at heater)"
− - "Natural gas, elevated pressure with at-heater regulator (2 psig and above)"
− - "Propane (LP), low-pressure (≤ 0.5 psig at heater)"
− - "Propane (LP), elevated pressure with at-heater regulator"
− - "Not applicable — electric, HPWH, or indirect-fired"
−default: "Natural gas, low-pressure (≤ 0.5 psig at heater)"
−```
−
−## Each heater shall be provided with a manual gas shutoff valve external to the heater jacket and within sight of the heater.
−
−## Each heater shall be provided with a sediment trap (dirt leg) downstream of the shutoff and immediately upstream of the heater inlet.
−
−## Each heater shall be provided with a union or dielectric flange between the shutoff valve and the heater for service disconnection.
−
−## Each heater shall be provided with a pressure gauge tap or test port for combustion startup.
−
−## Where the heater requires a supply pressure different from the building's distribution pressure, an in-line gas pressure regulator listed for the application shall be provided and vented per code.
−
−# Electrical Connection {toc}
−
−## Electric storage water heaters, heat-pump water heaters, controls for gas-fired heaters, power-vent fans, condensate pumps, and the recirculation pump shall be connected per NFPA 70.
−
−```datasheet
−label: Disconnect Type
−type: select
−options:
− - "Non-fused safety switch within sight of equipment"
− - "Fused safety switch within sight of equipment"
− - "Circuit breaker in panelboard within sight of equipment (where permitted)"
− - "Cord and plug connection (where permitted by code and listing)"
−default: "Non-fused safety switch within sight of equipment"
−```
−
−## Each piece of equipment shall be provided with a disconnect within sight of the equipment per NEC Article 422 (appliances) or Article 430 (motors) as applicable.
−
−## Equipment grounding and bonding for electric storage water heaters and HPWHs shall comply with [[sync/grounding-and-bonding]].
−
−## Branch-circuit conductor sizing, overcurrent protection, and the disconnect rating shall be coordinated with the equipment nameplate values and shall be [[drawing: as indicated on the electrical plans and panelboard schedules]].
−
−# Heat-Pump Water Heaters {toc}
−
−## Heat-pump water heaters (HPWHs) extract heat from ambient air and reject it into the stored water, achieving COP values of approximately 2 to 4 depending on ambient conditions. {note}
−
−## The backup heat source, or the absence of one, for each heat-pump water heater shall be specified.
−
−```datasheet
−label: HPWH Backup Heat Source
−type: select
−options:
− - "Integral electric-resistance backup (factory-installed)"
− - "No backup — HPWH only, sized for full load"
− - "Separate backup heater piped in series or parallel"
− - "Not applicable — not HPWH"
−default: "Integral electric-resistance backup (factory-installed)"
−```
−
−```datasheet
−label: HPWH Maximum Sound Level at 3 ft
−type: range
−unit: dBA
−options:
− min: 40
− max: 75
− step: 1
−default: 55
−```
−
−## The HPWH source-air space shall be sized large enough to avoid driving the supply ambient below the unit's minimum operating temperature.
−
−```datasheet
−label: HPWH Source-Air Configuration
−type: select
−options:
− - "Ambient air drawn from mechanical room (room must be sized adequately)"
− - "Ducted from outside — supply and return ducts"
− - "Ducted from outside — supply duct only with mechanical-room exhaust"
− - "Split-system with outdoor compressor and indoor storage tank"
− - "Not applicable — not HPWH"
−default: "Ambient air drawn from mechanical room (room must be sized adequately)"
−```
−
−## HPWH condensate generated by dehumidification of the source air shall be piped to a drain.
−
−## HPWH sound levels are higher than for resistance electric or gas-fired storage equipment and shall be evaluated against adjacent occupied spaces.
−
−## Refrigerant safety per UL 60335-2-40 governs the maximum allowable refrigerant charge for the installation environment, particularly for units using A2L refrigerants.
−
−# Temperature Setpoints and Legionella Control {toc}
−
−## Storage Temperature {toc}
−
−### Storage temperature shall be set in accordance with ASHRAE 188 to inhibit Legionella pneumophila multiplication.
−
−```datasheet
−label: Storage Temperature Setpoint
−type: select
−unit: °F
−options:
− - "140°F — ASHRAE 188 standard"
− - "135°F — ASHRAE 188 acceptable (lower limit of recommended range)"
− - "150°F — enhanced thermal disinfection (healthcare common)"
− - "160°F — high-temperature pasteurization service"
−default: "140°F — ASHRAE 188 standard"
−```
−
−### Legionella grows in the range of approximately 68°F to 122°F; storing water above 140°F provides reliable thermal disinfection of the storage volume, and storing above 122°F substantially reduces growth. {note}
−
−### Storage at 140°F or above is the standard recommendation for ASHRAE 188 compliance.
−
−### Healthcare facilities subject to NFPA 99 and applicable state health department requirements typically require storage at 140°F or higher with documented operational temperature logging.
−
−## Distribution Temperature {toc}
−
−### Distribution temperature downstream of the master mixing valve shall be maintained at or above 120°F to keep the entire recirculation loop above the Legionella growth range while delivering water at a temperature that does not require fixture-level scald protection beyond the point-of-use temperature-limiting devices specified in [[sync/plumbing-fixtures]].
−
−```datasheet
−label: Distribution Temperature Setpoint (Mixing Valve Outlet)
−type: select
−unit: °F
−options:
− - "120°F — ASHRAE 188 standard"
− - "124°F — enhanced Legionella control"
− - "115°F — only where every fixture has ASSE 1070 point-of-use control"
−default: "120°F — ASHRAE 188 standard"
−```
−
−### Distribution at lower temperatures may be approved where every fixture is served by an ASSE 1070 point-of-use device set to deliver water at the fixture, and where the recirculation return temperature is documented to remain above 110°F under all operating conditions.
−
−## Master Mixing Valve {toc}
−
−### A master mixing valve conforming to ASSE 1017 shall be installed immediately downstream of the water heater(s) or supplemental storage to blend stored water (140°F or higher) with cold water to deliver the distribution setpoint (typically 120°F) to the building.
−
−```datasheet
−label: Master Mixing Valve — ASSE 1017
−type: select
−options:
− - "Single ASSE 1017 valve sized for the design flow range"
− - "Parallel ASSE 1017 valves with sequenced isolation for wide turndown"
− - "ASSE 1017 with digital electronic mixing control and sensor feedback"
−default: "Single ASSE 1017 valve sized for the design flow range"
−```
−
−```datasheet
−label: Master Mixing Valve — Body Material
−type: radio
−options:
− - "Bronze body, brass trim, NSF 61/372"
− - "Stainless steel body, NSF 61/372"
−default: "Bronze body, brass trim, NSF 61/372"
−```
−
−### The mixing valve shall be selected with a turndown ratio sufficient to maintain accurate outlet temperature at the minimum recirculation flow rate during low-demand periods, and shall not be undersized such that the minimum draw exceeds its low-flow accuracy band.
−
−### Where the minimum flow exceeds the maximum capacity of a single ASSE 1017 valve, multiple valves shall be piped in parallel with isolation valves to permit one valve to operate during low demand and additional valves to bring online as flow increases.
−
−## Point-of-Use Temperature Limiting {toc}
−
−```datasheet
−label: Point-of-Use Temperature-Limiting Coverage
−type: radio
−options:
− - "All public lavatories, handwash stations, showers, and school/healthcare fixtures"
− - "Only fixtures where required by code (typical commercial baseline)"
− - "Project-specific scope per [[sync/plumbing-fixtures]]"
−default: "All public lavatories, handwash stations, showers, and school/healthcare fixtures"
−```
−
−### Fixtures requiring delivery temperature below the distribution setpoint — public lavatories, handwash stations, showers in any application, and any fixture in a school or healthcare facility — shall be served by an ASSE 1070 point-of-use temperature-limiting device installed at the fixture or fixture group.
−
−### Showers shall also be served by an ASSE 1016 anti-scald shower valve in addition to or in lieu of the ASSE 1070 device per the requirements of [[sync/plumbing-fixtures]].
−
−# Thermal Expansion Tank {toc}
−
−## A thermal expansion tank shall be installed on the cold-water inlet side of the water heater whenever the building is served through a backflow-preventing device — a reduced-pressure principle backflow assembly, a double-check valve, a pressure-reducing valve, or a check valve — that creates a closed system.
−
−```datasheet
−label: Thermal Expansion Tank
−type: radio
−options:
− - "Required — closed system (backflow preventer, PRV, or check valve present)"
− - "Not required — open system (no upstream check or backflow device)"
−default: "Required — closed system (backflow preventer, PRV, or check valve present)"
−```
−
−```datasheet
−label: Expansion Tank Diaphragm / Bladder Material
−type: radio
−options:
− - "Potable PE-X (cross-linked polyethylene) lined bladder, NSF 61"
− - "Butyl rubber bladder, NSF 61"
−default: "Potable PE-X (cross-linked polyethylene) lined bladder, NSF 61"
−```
−
−```datasheet
−label: Expansion Tank Acceptance Volume
−type: range
−unit: gal
−drawing_ref: true
−options:
− min: 1
− max: 80
− setpoints: [1, 2, 4.4, 8.5, 14, 20, 32, 44, 62, 80]
−default: 4.4
−```
−
−## In a closed system, the expansion of water when heated cannot return upstream to the utility main, so without an expansion tank the system pressure can rise to the T&P relief valve set pressure and cause repeated relief discharge, eventually compromising the relief valve seat. {note}
−
−## The expansion tank shall be sized using the manufacturer's published method based on the storage volume, the temperature rise from cold-water supply to setpoint, and the system supply pressure.
−
−## The expansion tank pre-charge pressure shall be set equal to the system static pressure at the expansion tank's installed elevation before the tank is connected to the water side of the system.
−
−## The Contractor shall measure system static pressure and adjust pre-charge before installation, not after.
−
−# Pressure and Temperature Relief {toc}
−
−## Each storage water heater and each indirect storage tank shall be provided with a combined temperature and pressure (T&P) relief valve conforming to ANSI Z21.22 / CSA 4.4, listed for the heater's input rating in Btu/h and the tank's working pressure in psi.
−
−```datasheet
−label: T&P Relief Valve Set Pressure
−type: select
−unit: psi
−options:
− - "75 psi"
− - "100 psi"
− - "125 psi"
− - "150 psi"
−default: "150 psi"
−```
−
−```datasheet
−label: T&P Relief Valve Set Temperature
−type: radio
−unit: °F
−options:
− - "210°F (standard)"
−default: "210°F (standard)"
−```
−
−```datasheet
−label: T&P Relief Discharge Piping
−type: select
−options:
− - "Copper Type L, full-size, to indirect-waste receptor with air gap"
− - "CPVC ASTM D2846, full-size, to indirect-waste receptor with air gap"
− - "Galvanized steel, full-size, to indirect-waste receptor with air gap"
−default: "Copper Type L, full-size, to indirect-waste receptor with air gap"
−```
−
−## The T&P relief valve shall be installed in a dedicated tapping at the top of the tank or at the location specified by the manufacturer's instructions; it shall not be valved off, and the inlet shall not be reduced in size.
−
−## The discharge from the T&P relief valve shall be piped full-size by gravity to a safe location of discharge — a floor drain or an indirect-waste receptor — such that any discharge is visible to building maintenance personnel and any thermal hazard is minimized.
−
−## Discharge piping shall be of a material rated for the relief temperature (typically 210°F) and shall terminate with an air gap above the receptor.
−
−# Recirculation System {toc}
−
−## In commercial buildings, domestic hot water must be delivered to fixtures within a time that satisfies both occupant comfort and the energy code.
−
−```datasheet
−label: Recirculation System Configuration
−type: select
−options:
− - "Pumped return to water heater inlet (standard)"
− - "Pumped return to a dedicated heater recirculation port"
− - "Pumped return to a recirculation tee on the cold-water inlet (uncommon)"
− - "Demand recirculation with point-of-use trigger"
− - "Not applicable — no recirculation required (small system)"
−default: "Pumped return to water heater inlet (standard)"
−```
−
−## Without a recirculation system, water in long horizontal branches stagnates, cools, and creates conditions favorable to Legionella in the dead leg; the recirculation system keeps water circulating continuously or on a controlled schedule through a return loop from the distribution piping back to the water heater, maintaining the return temperature above the Legionella threshold throughout the loop. {note}
−
−## The return-loop piping itself is the scope of [[sync/domestic-water-piping]]; this standard establishes the pump, control, and balancing requirements at the equipment. {note}
−
−## Recirculation Pump {toc}
−
−### The recirculation pump shall be an in-line centrifugal pump with bronze or stainless steel wetted parts, NSF/ANSI 61 certified, sized for the recirculation flow rate and head loss determined by the Engineer.
−
−```datasheet
−label: Recirculation Pump Wetted Material
−type: radio
−options:
− - "Bronze body and impeller (standard)"
− - "Stainless steel body and impeller (aggressive water)"
−default: "Bronze body and impeller (standard)"
−```
−
−```datasheet
−label: Recirculation Pump Motor
−type: select
−options:
− - "Wet-rotor permanent-magnet ECM (variable-speed, energy-efficient)"
− - "Wet-rotor fixed-speed (standard)"
− - "Inline centrifugal with separate motor"
−default: "Wet-rotor permanent-magnet ECM (variable-speed, energy-efficient)"
−```
−
−### The pump shall be installed with isolation valves on suction and discharge, a check valve on the discharge, unions for service removal, and a strainer on the suction where required by the manufacturer.
−
−### The pump motor shall be permanently lubricated, totally enclosed fan-cooled (TEFC) or open-drip-proof (ODP) as suitable for the mechanical-room environment, and rated for continuous duty at the design flow.
−
−## Recirculation Control {toc}
−
−### ASHRAE 90.1 requires that recirculation pumps not operate continuously when there is no demand. {note}
−
−### Control shall be by aquastat (return temperature sensor), time clock, demand-based trigger, or a combination, as required by the energy code in force and the building's operating schedule.
−
−```datasheet
−label: Recirculation Pump Control
−type: select
−options:
− - "Aquastat + time clock combination (standard)"
− - "Aquastat only (continuous-occupied applications)"
− - "Time clock only (legacy; not preferred for new construction)"
− - "Demand-based control (push-button, motion, or flow-sensor activation)"
− - "BAS integration with scheduled operation and temperature feedback"
−default: "Aquastat + time clock combination (standard)"
−```
−
−### Combined aquastat-plus-time-clock control is the most common commercial configuration — the time clock disables the pump during unoccupied hours, and the aquastat cycles the pump within occupied hours to maintain return temperature only when needed. {note}
−
−## Recirculation Balancing {toc}
−
−### Where the recirculation loop serves multiple branches or multiple risers, balancing is required so flow is proportional to the heat loss of each branch rather than taking the path of least resistance. {note}
−
−### Where the recirculation loop serves multiple branches or multiple risers, balancing valves or pressure-independent automatic balancing valves shall be provided at each branch take-off or riser base on the return circuit to ensure flow is proportional to the heat loss of each branch.
−
−```datasheet
−label: Recirculation Balancing Method
−type: select
−options:
− - "Manual balancing valve at each riser/branch with memory stop and flow indicator"
− - "Automatic pressure-independent thermostatic balancing valve at each branch"
− - "Not applicable — single-loop system with no branches"
−default: "Manual balancing valve at each riser/branch with memory stop and flow indicator"
−```
−
−### Without balancing, the shortest-path branches circulate at excess flow while the longest branches stagnate, defeating Legionella control in the dead legs. {note}
−
−### Balancing valve locations and setpoints shall be coordinated with [[sync/domestic-water-piping]] and are [[drawing: as indicated on the plumbing riser diagrams]].
−
−# Controls and Monitoring {toc}
−
−## Each water heater shall be provided with the safety and operating controls required for its equipment type and shall be integrated with the building automation system as specified below.
−
−```datasheet
−label: BAS Integration
−type: select
−options:
− - "Monitor only — supply temperature, return temperature, pump status, alarm"
− - "Monitor and schedule — setpoints and operating schedule from BAS"
− - "Full BAS integration — read/write of setpoints, sequences, and diagnostics"
− - "No BAS integration — standalone controls"
−default: "Monitor only — supply temperature, return temperature, pump status, alarm"
−```
−
−```datasheet
−label: Recirculation Return Temperature Sensor
−type: radio
−options:
− - "Thermowell-mounted RTD with BAS input"
− - "Thermowell-mounted thermistor with BAS input"
− - "Surface-mount strap-on (not preferred — accuracy concerns)"
−default: "Thermowell-mounted RTD with BAS input"
−```
−
−## Each water heater shall be provided with an operating thermostat (or modulating control as applicable to the equipment), a high-temperature limit cutout, a flame safeguard (gas) or thermal cutout (electric), a low-water cutoff where required by code or by ASME CSD-1, and the manufacturer's required combustion safety controls.
−
−## The factory-supplied control package shall not be modified in the field; field-supplied controls shall be limited to those external to the appliance and shall not defeat any safety function of the factory controls.
−
−## BAS points and communication protocol shall be coordinated with [[sync/building-automation-system]].
−
−## Where the BAS provides monitoring of recirculation return temperature for Water Management Program compliance, the temperature sensor shall be installed in a thermowell at the heater inlet (return) and shall be calibrated at startup to within ±2°F of a traceable reference.
−
−# Installation {toc}
−
−## Equipment Setting {toc}
−
−```datasheet
−label: Seismic Anchorage
−type: select
−options:
− - "Not required — SDC A or B"
− - "Two-strap horizontal anchorage to structure (SDC C and above, standard)"
− - "OSHPD / IAPMO pre-approved detail (high-seismic, healthcare)"
− - "Project-specific engineered anchorage"
−default: "Not required — SDC A or B"
−```
−
−### Equipment shall be set level on a housekeeping pad or on the manufacturer's specified support.
−
−### Tank-type heaters in seismic regions shall be anchored per the project's seismic anchorage details — typically two horizontal straps (upper and lower) anchored to adjacent structure or to a strut frame, with the heater isolated from rigid contact by manufacturer-furnished or field-cut spacers where required.
−
−### Pre-approved seismic anchorage details (OSHPD, IAPMO, or AHJ-accepted) shall be used where available to avoid project-specific engineering for the anchorage.
−
−## Piping Connections {toc}
−
−```datasheet
−label: Heater Piping Connection Method
−type: radio
−options:
− - "Unions on inlet and outlet (sizes through 2 in.)"
− - "Flanged connections on inlet and outlet (sizes 2-1/2 in. and larger)"
− - "Grooved mechanical couplings (where listed for application)"
−default: "Unions on inlet and outlet (sizes through 2 in.)"
−```
−
−### Cold-water inlet, hot-water outlet, and recirculation-return connections shall be made with unions or flanged connections (depending on size) between the heater and the building piping to permit heater service and replacement without cutting the building piping.
−
−### Each heater piping connection shall include an isolation valve.
−
−### Dielectric isolation shall be provided between the heater connections (typically copper or bronze) and any ferrous building piping per [[sync/domestic-water-piping]].
−
−### Drain valves at the tank tapping shall be full-port ball valves with female hose-thread outlets, NSF 61/372 certified, with a threaded cap on the outlet.
−
−### The Contractor shall verify that the drain valve location and the floor-drain layout permit complete drain-down of the tank without flooding.
−
−## Gauges and Thermometers {toc}
−
−### Each heater shall be provided with a pressure gauge on the inlet (cold) and a combination pressure-temperature gauge on the outlet (hot).
−
−### The mixing valve outlet shall be provided with a temperature gauge or thermometer.
−
−### The recirculation pump suction shall be provided with a temperature gauge or BAS sensor as established in Controls and Monitoring.
−
−### Gauges and thermometers shall be installed in a position visible from the front of the heater without removing covers or shields.
−
−## Labeling and Valve Tagging {toc}
−
−```datasheet
−label: Valve and Equipment Tagging
−type: radio
−options:
− - "Engraved brass tags with chain or wire attachment (durable, preferred)"
− - "Photo-laminated plastic tags with chain or wire attachment"
−default: "Engraved brass tags with chain or wire attachment (durable, preferred)"
−```
−
−### Each heater, mixing valve, expansion tank, recirculation pump, and isolation valve shall be labeled with a permanent engraved or photo-laminated tag indicating the equipment identifier from the equipment schedule, the service (DHW supply, DHW recirculation, etc.), and any required setpoint.
−
−### Valve tags shall be coordinated with the as-built piping schematic so a maintenance technician can identify and trace any tagged valve without ambiguity.
−
−# Testing and Startup {toc}
−
−## Pre-Startup Inspection {toc}
−
−### Before startup, the Contractor shall verify that the heater is correctly piped (inlet and outlet connections in the correct ports), that all isolation valves are open, that the tank is filled and vented of air, that the T&P relief valve is installed and the discharge piping is open and routed to a receptor, that the expansion tank pre-charge is correct, that the gas supply pressure (static) is within the heater's listed range, that the electrical disconnect is energized, that the venting is complete and unobstructed, and that the condensate drain (Category IV) is open and routed.
−
−## Startup {toc}
−
−### Startup shall be performed by a factory-authorized technician for any heater with a manufacturer-required commissioning procedure, or by a qualified plumber/mechanic where the manufacturer accepts contractor startup.
−
−### The startup procedure shall include confirmation of fuel-gas dynamic supply pressure; manifold pressure setting; combustion testing (CO, CO₂, stack temperature) at high-fire and at low-fire/lowest stable rate; verification of high-temperature cutout operation by simulated overtemperature; verification of T&P relief valve operation by manual test lever; verification of recirculation pump rotation, flow, and aquastat function; setting of storage temperature and mixing-valve outlet temperature; and recording of all setpoints and as-found / as-left values in the startup report.
−
−## Field Performance Test {toc}
−
−### Following startup, a field performance test shall be conducted to verify the items listed below.
−
−```datasheet
−label: Field Performance Test — Required Documentation
−type: checkbox
−options:
− - "Outlet temperature at heater (storage setpoint verification)"
− - "Outlet temperature at mixing valve (distribution setpoint verification)"
− - "Recirculation return temperature at heater inlet"
− - "T&P relief valve manual test"
− - "Combustion test report (gas-fired)"
− - "HPWH heating capacity and condensate verification"
− - "Recirculation pump aquastat and control verification"
− - "Expansion tank pre-charge verification"
−default: "Outlet temperature at heater (storage setpoint verification)"
−```
−
−### The field performance test shall verify outlet temperature at the heater within ±5°F of the storage setpoint after a recovery cycle from a fully drawn-down condition.
−
−### The field performance test shall verify outlet temperature downstream of the master mixing valve within ±5°F of the distribution setpoint at the design flow rate and at a minimum draw representative of nighttime recirculation-only operation.
−
−### The field performance test shall verify recirculation return temperature at the heater inlet equal to or greater than the distribution setpoint minus 10°F (typically ≥ 110°F when distribution is 120°F).
−
−### The field performance test shall verify no discharge from the T&P relief valve during normal operation, including during recovery from full draw with the expansion tank in service.
−
−### The field performance test shall verify combustion test results within the manufacturer's published range.
−
−### For HPWH, the field performance test shall verify measured heating capacity within 90 percent of the manufacturer's published capacity at the test conditions, and no condensate accumulation in the equipment cabinet.
−
−## Disinfection {toc}
−
−### The water heater and storage tank shall be disinfected as part of the building's domestic-water system disinfection per [[sync/domestic-water-piping]] before being placed in service for potable use.
−
−# Delivery, Storage, and Handling {toc}
−
−## Water-heating equipment shall be delivered to the site in the manufacturer's original packaging, with all factory protective covers, plugs, and tags in place.
−
−## Equipment shall be inspected at delivery for shipping damage; damaged equipment shall be reported in writing to the carrier and to the manufacturer's authorized representative before installation and shall not be installed without disposition.
−
−## Equipment shall be stored indoors, on level dunnage, protected from freezing, weather, construction water, and physical damage until installed.
−
−## Storage tanks and packaged heaters with factory insulation shall not be stacked.
−
−## Refrigerant-containing HPWHs shall be stored upright and shall not be tipped beyond the manufacturer's permitted shipping orientation.
−
−## Tipping a HPWH on its side can displace compressor oil and require an extended power-off settling period before startup. {note}
−
−## Vent components, gas piping, condensate piping, and small electrical components shall be stored in their original packaging, segregated from other trades' materials, and protected from foot traffic and construction dust.
−
−# Warranty {toc}
−
−## The Contractor shall procure equipment carrying the standard manufacturer's warranty for the equipment category, and the warranty period shall commence at substantial completion or per the manufacturer's published policy.
−
−```datasheet
−label: Warranty Requirement
−type: select
−options:
− - "Manufacturer standard warranty"
− - "Manufacturer standard + extended parts (5 years minimum)"
− - "Manufacturer standard + extended parts and labor (5 years minimum)"
− - "Project-specified warranty per equipment schedule"
−default: "Manufacturer standard warranty"
−```
−
−## Standard commercial warranties typically include: tank (storage water heaters) 3 to 10 years; heat exchanger (gas-fired) 5 to 15 years; compressor (HPWH) 5 to 10 years; all other components 1 year parts. {note}
−
−## Where extended warranties or labor coverage are required by the contract documents, the requirement shall be stated explicitly in the equipment schedule and shall be documented in the closeout submittals.
−
−## Warranty exclusions for water chemistry outside the manufacturer's stated acceptable range shall be acknowledged by the Owner in the project documents.
−
−# Spare Parts {toc}
−
−## The Contractor shall deliver to the Owner at substantial completion the following spare parts, marked with the equipment identifier and stored in a labeled container in the mechanical room or in a location designated by the Owner.
−
−- One complete set of replacement gaskets for each unique heater connection and each unique mixing valve
−- One spare sacrificial anode rod for each glass-lined tank
−- One spare T&P relief valve per unique set pressure / set temperature combination
−- One spare recirculation pump cartridge or pump head (for cartridge-style wet-rotor pumps) per unique pump model
−- One spare expansion tank diaphragm assembly per unique expansion tank model (where field-replaceable)
−- One spare aquastat or temperature controller per unique model
−- For Category IV equipment, one spare condensate-neutralizer media charge
−
−```datasheet
−label: Spare Parts Delivery
−type: checkbox
−options:
− - "Replacement gaskets for heater and mixing valve connections"
− - "Spare sacrificial anode rod (one per glass-lined tank)"
− - "Spare T&P relief valve (one per unique set pressure)"
− - "Spare recirculation pump cartridge or pump head"
− - "Spare expansion tank diaphragm assembly (field-replaceable models)"
− - "Spare aquastat or temperature controller"
− - "Spare condensate-neutralizer media (Category IV)"
−default: "Replacement gaskets for heater and mixing valve connections"
−```
−
−## The Contractor shall deliver the spare parts listed above to the Owner at substantial completion, marked with the equipment identifier and stored in a labeled container in the mechanical room or a location designated by the Owner.
+---
+title: Commercial Water Heaters
+category: Plumbing
+description: >
+ When to use: Equipment that generates and stores domestic hot water for commercial, institutional, and industrial buildings — fuel-fired and electric storage water heaters, instantaneous and semi-instantaneous water heaters, heat pump water heaters, and indirect-fired storage vessels heated by a boiler plant, a solar loop, or recovered heat. Covers the storage vessel and its corrosion protection, the combustion air and vent system, the fuel gas and electrical connections at the equipment, condensate handling, thermal expansion control, temperature and pressure relief, the master mixing valve, the recirculation pump and its controls and balancing, equipment anchorage, startup, and field performance testing.
+
+ Not intended for: Domestic water piping upstream or downstream of the equipment ([[sync/domestic-water-piping]]); the fixtures and fittings served ([[sync/plumbing-fixtures]]); the drainage system receiving relief, condensate, and drain-down discharge ([[sync/sanitary-waste-and-vent-piping]]); the building water service backflow assembly ([[sync/backflow-prevention]]); fuel gas piping upstream of the heater connection ([[sync/fuel-gas-piping]]); boilers generating heat for space-heating loops ([[sync/boilers]]); solar thermal collector arrays and their collector-loop piping; swimming pool, spa, and process water heating above domestic delivery temperatures; and steam-to-water generation in a central steam plant.
+---
+
+# Scope {toc}
+
+## This standard governs the equipment that heats and stores domestic hot water, together with the vessels, controls, vent system, safety devices, and service connections that make that equipment operate safely and predictably. {note}
+
+## The scope begins at the cold water inlet connection to the heater or storage vessel and ends at the hot water outlet downstream of the master mixing valve and at the recirculation return connection. {note}
+
+## The following are governed elsewhere and are outside this standard: {note}
+
+- the domestic water piping that conveys water to and from the equipment, including the recirculation return main itself
+- the fixtures, faucets, showers, and emergency fixtures the system serves
+- the sanitary drainage and vent piping that receives relief valve, condensate, and tank drain-down discharge
+- the backflow prevention assembly on the building water service
+- the fuel gas piping upstream of the shutoff valve at the heater
+- boilers, boiler plant piping, and the hydronic loops that serve space heating
+- solar thermal collectors, collector-loop piping, and the collector-loop heat transfer fluid
+- pool, spa, and process water heating, and any domestic-quality water heated above the delivery temperatures addressed here
+
+## The Contractor shall install water heating equipment in the locations shown on [[drawing: the plumbing plans]].
+
+## Every component of this equipment that contacts potable water shall be certified to NSF/ANSI/CAN 61 for health effects and to NSF/ANSI/CAN 372 for lead content.
+
+## The NSF/ANSI/CAN 372 lead content limit is a federal requirement under the Reduction of Lead in Drinking Water Act and shall not be waived at the project level.
+
+## This standard establishes the temperature setpoints, mixing arrangements, monitoring points, and recirculation requirements at the equipment that a building water management program depends on. {note}
+
+## Building-wide Legionella risk management is the subject of a water management program developed for the project under ASHRAE 188 by the Owner and the design team; the equipment requirements here support that program but do not constitute it. {note}
+
+# Referenced Standards {toc}
+
+## Equipment, materials, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited.
+
+## Where the contract documents, the Authority Having Jurisdiction, or two referenced standards impose conflicting requirements, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
+
+## The adopted plumbing code, mechanical code, and fuel gas code shall take precedence over every other reference on any matter those codes address directly.
+
+| Standard | Title |
+|----------|-------|
+| ASHRAE 188 | Legionellosis: Risk Management for Building Water Systems |
+| ASHRAE Guideline 12 | Managing the Risk of Legionellosis Associated with Building Water Systems |
+| ASHRAE 90.1 | Energy Standard for Sites and Buildings Except Low-Rise Residential Buildings |
+| ASHRAE 62.1 | Ventilation and Acceptable Indoor Air Quality |
+| IECC | International Energy Conservation Code |
+| IPC | International Plumbing Code |
+| UPC | Uniform Plumbing Code |
+| 10 CFR Part 430 | Energy Conservation Program for Consumer Products (uniform energy factor) |
+| 10 CFR Part 431 | Energy Conservation Program for Certain Commercial and Industrial Equipment (thermal efficiency and standby loss) |
+| ANSI Z21.10.1 / CSA 4.1 | Gas Water Heaters, Volume I — Storage Water Heaters with Input Ratings of 75,000 Btu/h and Less |
+| ANSI Z21.10.3 / CSA 4.3 | Gas-Fired Water Heaters, Volume III — Storage Water Heaters with Input Ratings Above 75,000 Btu/h, Circulating and Instantaneous |
+| ANSI Z21.22 / CSA 4.4 | Relief Valves for Hot Water Supply Systems |
+| UL 174 | Household Electric Storage Tank Water Heaters |
+| UL 732 | Oil-Fired Storage Tank Water Heaters |
+| UL 1453 | Electric Booster and Commercial Storage Tank Water Heaters |
+| UL 60335-2-40 / CSA C22.2 No. 60335-2-40 | Household and Similar Electrical Appliances — Particular Requirements for Electrical Heat Pumps, Air-Conditioners and Dehumidifiers |
+| AHRI 1300 | Performance Rating of Commercial Heat Pump Water Heaters |
+| UL 103 | Factory-Built Chimneys for Residential Type and Building Heating Appliances |
+| UL 641 | Type L Low-Temperature Venting Systems |
+| UL 1738 | Venting Systems for Gas-Burning Appliances, Categories II, III, and IV |
+| NFPA 54 / ANSI Z223.1 | National Fuel Gas Code |
+| IFGC | International Fuel Gas Code |
+| NFPA 31 | Installation of Oil-Burning Equipment |
+| NFPA 70 | National Electrical Code |
+| ASME BPVC Section IV | Rules for Construction of Heating Boilers (Part HLW, potable water heaters) |
+| ASME BPVC Section VIII Division 1 | Rules for Construction of Pressure Vessels |
+| ASME CSD-1 | Controls and Safety Devices for Automatically Fired Boilers |
+| ASME A112.4.1 | Water Heater Relief Valve Drain Tubes |
+| NSF/ANSI 5 | Water Heaters, Hot Water Supply Boilers, and Heat Recovery Equipment |
+| NSF/ANSI/CAN 61 | Drinking Water System Components — Health Effects |
+| NSF/ANSI/CAN 372 | Drinking Water System Components — Lead Content |
+| ASSE 1016 | Automatic Compensating Valves for Individual Showers and Tub/Shower Combinations |
+| ASSE 1017 | Temperature Actuated Mixing Valves for Hot Water Distribution Systems |
+| ASSE 1069 | Automatic Temperature Control Mixing Valves |
+| ASSE 1070 / ASME A112.1070 / CSA B125.70 | Water Temperature Limiting Devices |
+| ASSE 1071 | Temperature Actuated Mixing Valves for Plumbed Emergency Equipment |
+| ASSE 1082 | Water Heaters with Integral Temperature Control Devices for Hot Water Distribution Systems |
+| ASCE 7 | Minimum Design Loads and Associated Criteria for Buildings and Other Structures |
+| 40 CFR Part 82 Subpart F | Recycling and Emissions Reduction (refrigerant handling certification) |
+
+# Submittals {toc}
+
+## Action Submittals {toc}
+
+### The Contractor shall submit the following for review before any water heating equipment is procured:
+
+- product data for each water heater, giving the fuel or energy source, input rating, storage volume, recovery rate at a stated temperature rise, efficiency rating and the metric it is expressed in, vent category, permitted vent materials with the maximum equivalent vent length, electrical characteristics, gas train inlet pressure range, and the safety certification the unit carries
+- product data for each storage vessel, giving the lining, working pressure rating, insulation thermal resistance, tapping schedule, anode provisions and the clearance required to withdraw an anode, and the pressure vessel certification where one applies
+- product data for the master mixing valve, giving the body material, connection sizes, the flow range over which the published outlet temperature accuracy is held, setpoint range, and integral checks and stops
+- product data for the thermal expansion vessel, giving the acceptance volume, total volume, factory pre-charge, wetted materials, and potable-contact certification
+- product data for the recirculation pump, giving the pump curve, wetted materials, motor type and electrical data, and potable-contact certification
+- product data for the temperature and pressure relief valve, giving the set pressure, set temperature, relieving capacity, and outlet size
+- product data for the vent system, giving the listed material, joint method, support spacing, and termination assemblies
+- product data for the condensate neutralizer, giving the media type, media volume, and the condensate flow rate the unit is rated for
+- a piping schematic of the water heating assembly showing every heater, vessel, mixing valve, expansion vessel, pump, relief valve, isolation valve, drain, gauge, and thermometer, with each valve carrying the tag number it will bear in the field
+
+```datasheet
+label: Action Submittal Package
+type: checkbox
+options:
+ - "Water heater product data"
+ - "Storage vessel product data"
+ - "Master mixing valve product data"
+ - "Thermal expansion vessel product data"
+ - "Recirculation pump product data"
+ - "Temperature and pressure relief valve product data"
+ - "Vent system product data"
+ - "Condensate neutralizer product data"
+ - "Piping schematic with valve tag numbers"
+```
+
+### Fabrication and installation of water heating equipment shall not begin until the corresponding action submittals have been reviewed and returned.
+
+## Informational Submittals {toc}
+
+### The Contractor shall submit the following supporting calculations and certifications with, or before, the action submittals:
+
+- vent sizing calculations for each vent system, including the total equivalent length, the fitting allowances used, and the common-vent method where more than one appliance shares a vent
+- combustion air calculations for each fuel-fired unit, showing the method and the free opening or duct area the method yields
+- the high-altitude input derate the equipment requires at the project elevation, with the source of the derate identified
+- thermal expansion vessel sizing calculations showing the inputs used and the resulting acceptance volume
+- seismic anchorage calculations sealed by a registered design professional, or the pre-approved anchorage detail the Contractor intends to use, with the detail's listing identified
+- an evaluation of the incoming water analysis against the water chemistry limits the selected equipment is published to tolerate
+- documentation that the startup technician holds the certification required by this standard
+- documentation that every technician who will open a refrigerant circuit holds the certification required under 40 CFR Part 82 Subpart F
+
+```datasheet
+label: Informational Submittal Package
+type: checkbox
+options:
+ - "Vent sizing calculations"
+ - "Combustion air calculations"
+ - "High-altitude input derate"
+ - "Thermal expansion vessel sizing calculations"
+ - "Seismic anchorage calculations or pre-approved detail"
+ - "Incoming water analysis evaluation"
+ - "Startup technician certification"
+ - "Refrigerant handling certification"
+```
+
+## Closeout Submittals {toc}
+
+### The Contractor shall submit the following before the water heating system is accepted:
+
+- an as-built piping schematic recording the installed configuration, the valve tag numbers as fitted, and the final routing of the vent, gas, electrical, condensate, and drainage connections
+- operation and maintenance manuals for every item of equipment furnished under this standard, with the recommended maintenance tasks and their intervals tabulated
+- the startup report for each unit, signed by the technician who performed it, recording the as-found and as-left value of every setting that was adjusted
+- combustion test results for each fuel-fired unit at high fire and at the lowest stable firing rate
+- the field performance test report required by this standard
+- a record of every temperature setpoint as left, the recirculation control schedule as programmed, and the monitoring points made available to the Owner, in the form the Owner's water management program uses
+- warranty documentation for each item of equipment, identifying the coverage period and the date coverage begins
+- a signed receipt from the Owner for the spare parts delivered
+
+```datasheet
+label: Closeout Submittal Package
+type: checkbox
+options:
+ - "As-built piping schematic with valve tag numbers"
+ - "Operation and maintenance manuals"
+ - "Signed startup reports"
+ - "Combustion test results"
+ - "Field performance test report"
+ - "Setpoint and monitoring point record"
+ - "Warranty documentation"
+ - "Spare parts receipt"
+```
+
+# Quality Assurance {toc}
+
+## Installer and Startup Qualifications {toc}
+
+### Each portion of the installation shall be performed by personnel holding the license the Authority Having Jurisdiction requires for that trade.
+
+### Startup shall be performed by a technician certified by the equipment manufacturer wherever the manufacturer conditions the warranty on a factory-authorized startup.
+
+### Where the manufacturer accepts contractor startup, startup shall be performed by a technician who has completed the manufacturer's training for the equipment class being started.
+
+### Refrigerant circuits shall be opened, charged, and serviced only by a technician certified under 40 CFR Part 82 Subpart F.
+
+### The Contractor shall have the required certifications on site and available for inspection before startup begins.
+
+## Product Listing and Certification {toc}
+
+### Each water heater shall bear the certification mark of a Nationally Recognized Testing Laboratory for the product safety standard that applies to its class.
+
+### Electric storage water heaters exceeding 120 gal capacity, exceeding 12 kW input, or provided with controls permitting a stored water temperature above 77°C (171°F) shall be listed to UL 1453 rather than UL 174.
+
+### Storage vessels for which pressure vessel construction is required under this standard shall bear the certification stamp of the applicable ASME Boiler and Pressure Vessel Code section.
+
+### Equipment serving food service, laundry, or other hygiene-sensitive processes shall bear an NSF/ANSI 5 listing where the Authority Having Jurisdiction or the Owner's operating permit requires one.
+
+## Pressure Vessel Construction {toc}
+
+### A potable water heater falls outside the ASME Boiler and Pressure Vessel Code Section IV Part HLW exemption once any one of its rated input, its storage volume, or its maximum operating temperature crosses the exemption limit; below all three limits the appliance is built to its safety listing alone. {note}
+
+### A fired water heater exceeding 200,000 Btu/h input, exceeding 120 gal storage volume, or controlled to a water temperature above 210°F shall be constructed and stamped to ASME Boiler and Pressure Vessel Code Section IV Part HLW.
+
+### An unfired storage vessel exceeding the same limits shall be constructed and stamped to ASME Boiler and Pressure Vessel Code Section VIII Division 1.
+
+### Equipment fired automatically at or above 400,000 Btu/h input shall carry the controls and safety devices required by ASME CSD-1 where the Authority Having Jurisdiction adopts that standard.
+
+### Storage volume shall not be reduced below the volume the load calculation calls for in order to stay under a pressure vessel construction limit.
+
+# Service Conditions at the Equipment {toc}
+
+## Equipment Room Conditions {toc}
+
+### The equipment room shall be maintained above freezing throughout the year.
+
+### Any portion of the equipment, relief piping, or condensate piping that passes through a space subject to freezing shall be freeze-protected.
+
+### The equipment room shall be provided with a floor drain, floor sink, or indirect waste receptor able to accept the relief valve discharge, the condensate discharge, and a full vessel drain-down without flooding the room.
+
+### Where no gravity receptor can be provided, a sump with a duplex pump shall be provided.
+
+### The sump shall alarm on high level to the monitoring interface specified in this standard.
+
+### Combustion equipment loses rated input with elevation, and a unit selected at its sea-level rating will not meet its scheduled recovery at a high-altitude site. {note}
+
+### Fuel-fired equipment shall be derated for [[parameter: altitude]] in accordance with the equipment manufacturer's published high-altitude data, or in accordance with NFPA 54 where the manufacturer publishes none.
+
+## Incoming Water Chemistry {toc}
+
+### Hardness deposits on the hottest wetted surface first, so scale shortens the life of immersion elements, fire tubes, and brazed-plate exchangers well before it affects the storage vessel; chloride attacks stainless linings, and an aggressive low-alkalinity water consumes a sacrificial anode quickly. {note}
+
+### The Contractor shall evaluate the incoming water analysis against the published water chemistry limits of the selected equipment and shall report any exceedance before the equipment is ordered.
+
+### Scale control at the equipment shall be provided as indicated in the datasheet.
+
+```datasheet
+label: Scale Control at the Equipment
+type: select
+derived: "[[parameter: site-water-supply-hardness]] evaluated against the maximum hardness the selected equipment is published to tolerate at the storage temperature setpoint"
+options:
+ - "None"
+ - "Softened supply to the water heater"
+ - "Blended softened and unsoftened supply to the water heater"
+ - "Template-assisted crystallization scale inhibitor"
+ - "Sequestering chemical feed"
+default: derived
+```
+
+### Softening, filtration, and chemical feed equipment upstream of the water heater is the subject of [[sync/domestic-water-softeners-and-filtration]]. {note}
+
+### The Contractor shall not be held responsible for equipment failure caused by water chemistry outside the equipment manufacturer's published limits where the exceedance was reported under this article and the equipment was installed and started up as specified.
+
+## Service and Replacement Clearances {toc}
+
+### Service clearances shall equal or exceed both the equipment manufacturer's published minimums and the working space NFPA 70 requires at the electrical disconnecting means.
+
+### Clear vertical space equal to the anode length plus the withdrawal allowance the equipment manufacturer publishes shall be maintained above every vessel fitted with a rigid anode.
+
+### Where the available vertical space is less than that clearance, a segmented or flexible anode listed by the vessel manufacturer for the vessel shall be furnished.
+
+### The equipment shall be set so that the largest single component requiring replacement can be removed from the room without dismantling permanent building construction.
+
+# Energy Source and Heater Configuration {toc}
+
+## The energy source and the heater configuration are two separate decisions: the same building load can be met by a storage heater, an instantaneous heater, or an indirect vessel on any of several energy sources, and each pairing carries a different footprint, vent requirement, and standby loss. {note}
+
+## The energy source that heats the domestic water shall be as indicated in the datasheet.
+
+```datasheet
+label: Domestic Hot Water Energy Source
+type: select
+options:
+ - "Natural gas"
+ - "Propane"
+ - "Fuel oil"
+ - "Electric resistance"
+ - "Electric heat pump"
+ - "Hot water from a boiler plant"
+ - "Steam from a central plant"
+ - "Solar thermal loop"
+ - "Recovered heat from a refrigeration or process system"
+```
+
+## Where the datasheet selects natural gas as the energy source, the Contractor shall confirm that [[parameter: site-natural-gas-service]] delivers the inlet pressure and the full-fire input the equipment requires at the point of connection, and shall report any shortfall before the equipment is ordered.
+
+## The heater configuration shall be as indicated in the datasheet.
+
+```datasheet
+label: Heater Configuration
+type: select
+options:
+ - "Storage water heater with an integral vessel"
+ - "Instantaneous water heater without storage"
+ - "Semi-instantaneous water heater with an integral buffer volume"
+ - "Indirect-fired storage vessel with an internal heat exchanger coil"
+ - "External heat exchanger with a separate unfired storage vessel"
+ - "Booster heater serving a single elevated-temperature load"
+```
+
+## A storage configuration absorbs a peak draw with volume and recovers slowly, so it tolerates a spiky load on a modest input; an instantaneous configuration carries the peak on input alone, which removes standby loss and footprint but requires the full peak input and a minimum activation flow. {note}
+
+## Where the datasheet selects an instantaneous or semi-instantaneous configuration, the selected unit shall stabilize outlet temperature within the delivery tolerance specified in this standard at a draw as low as the smallest single fixture the system serves.
+
+## The burner control mode shall be as indicated in the datasheet.
+
+```datasheet
+label: Burner Control Mode
+type: select
+options:
+ - "Single stage"
+ - "Two stage"
+ - "Modulating"
+```
+
+## Combustion technology shall be as indicated in the datasheet.
+
+```datasheet
+label: Combustion Technology
+type: select
+derived: "the equipment class selected and the federal minimum thermal efficiency in force under 10 CFR Part 431 or 10 CFR Part 430 at the date of manufacture"
+options:
+ - "Condensing"
+ - "Non-condensing"
+ - "Not applicable to the selected energy source"
+default: derived
+```
+
+## The federal minimum thermal efficiency for commercial gas-fired water heating equipment reaches a level that only condensing combustion attains, so for most fuel-fired equipment classes the condensing decision is settled by the rule in force on the manufacturing date rather than by the project. {note}
+
+## The redundancy arrangement shall be as indicated in the datasheet.
+
+```datasheet
+label: Redundancy Arrangement
+type: select
+options:
+ - "A single unit carrying the full load"
+ - "Multiple units sharing the load with no standby capacity"
+ - "Multiple units sharing the load with one unit held as standby"
+ - "Multiple units each sized for the full load"
+```
+
+## Where the datasheet selects a standby arrangement, the control system shall rotate the lead unit on a schedule the Owner can adjust.
+
+## Where the datasheet selects a standby arrangement, the standby unit shall start automatically on failure of a running unit.
+
+## A standby unit that is never rotated into service accumulates stagnant water at the temperature Legionella favors, which is why lead rotation is required rather than optional. {note}
+
+# Capacity and Storage {toc}
+
+## Storage volume, input rating, and recovery rate are the outputs of the Engineer's load calculation and are recorded on the equipment schedule; this standard governs what the equipment must do once those numbers are set. {note}
+
+## Storage volume shall be as indicated in the datasheet.
+
+```datasheet
+label: Storage Volume
+type: range
+unit: gal
+drawing_ref: "the plumbing equipment schedule"
+options:
+ min: 0
+ max: 5000
+ setpoints: [0, 6, 20, 40, 50, 80, 100, 119, 175, 250, 350, 500, 750, 1000, 1500, 2000, 3000, 5000]
+default: deferred
+```
+
+## Fuel-fired input rating shall be as indicated in the datasheet.
+
+```datasheet
+label: Fuel-Fired Input Rating
+type: range
+unit: Btu/h
+drawing_ref: "the plumbing equipment schedule"
+options:
+ min: 30000
+ max: 6000000
+ setpoints: [30000, 50000, 75000, 100000, 150000, 199000, 300000, 400000, 500000, 750000, 1000000, 1500000, 2000000, 3000000, 4000000, 6000000]
+default: deferred
+```
+
+## Electric input rating shall be as indicated in the datasheet.
+
+```datasheet
+label: Electric Input Rating
+type: range
+unit: kW
+drawing_ref: "the plumbing equipment schedule"
+options:
+ min: 1
+ max: 480
+ setpoints: [1, 3, 6, 9, 12, 18, 24, 36, 54, 72, 90, 120, 150, 180, 240, 300, 360, 480]
+default: deferred
+```
+
+## Recovery capacity shall be as indicated in the datasheet.
+
+```datasheet
+label: Recovery Capacity
+type: range
+unit: GPH
+drawing_ref: "the plumbing equipment schedule"
+options:
+ min: 5
+ max: 6000
+ setpoints: [5, 15, 30, 50, 100, 200, 350, 500, 750, 1000, 1500, 2000, 3000, 4500, 6000]
+default: deferred
+```
+
+## A recovery rate is meaningless without the temperature rise it was measured across, and the rise a project actually sees is fixed by how cold the incoming water is at the design condition. {note}
+
+## The temperature rise against which recovery capacity is rated shall be as indicated in the datasheet.
+
+```datasheet
+label: Recovery Rating Temperature Rise
+type: range
+unit: °F
+derived: "the storage temperature setpoint less [[parameter: site-water-supply-temperature-minimum]]"
+options:
+ min: 30
+ max: 140
+ setpoints: [30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 140]
+default: derived
+```
+
+## The Contractor shall confirm the selected equipment's published recovery rate at the rating temperature rise indicated in the datasheet, and shall report any shortfall against the scheduled recovery capacity before the equipment is ordered.
+
+# Efficiency and Standby Loss {toc}
+
+## Federal energy conservation standards, ASHRAE 90.1, and the adopted energy code each set a floor; the equipment must clear whichever floor is highest for its class. {note}
+
+## Each water heater shall meet or exceed the highest applicable minimum efficiency imposed by 10 CFR Part 430, 10 CFR Part 431, ASHRAE 90.1, and the adopted energy code for its equipment class.
+
+## The metric in which efficiency is expressed and verified shall be as indicated in the datasheet.
+
+```datasheet
+label: Efficiency Rating Metric
+type: select
+derived: "the equipment class of the selected water heater and the federal test procedure that class falls under"
+options:
+ - "Uniform energy factor"
+ - "Thermal efficiency with standby loss"
+ - "Coefficient of performance at AHRI 1300 rating conditions"
+default: derived
+```
+
+## Minimum thermal efficiency for fuel-fired equipment shall be as indicated in the datasheet.
+
+```datasheet
+label: Minimum Thermal Efficiency — Fuel-Fired Equipment
+type: range
+unit: '%'
+derived: "the equipment class of the selected water heater and the federal minimum thermal efficiency in force for that class at the date of manufacture"
+options:
+ min: 75
+ max: 99
+ setpoints: [75, 78, 80, 82, 84, 88, 90, 92, 94, 95, 96, 97, 98, 99]
+default: derived
+```
+
+## Minimum uniform energy factor for residential-duty equipment shall be as indicated in the datasheet.
+
+```datasheet
+label: Minimum Uniform Energy Factor — Residential-Duty Equipment
+type: range
+derived: "the draw pattern and rated storage volume of the selected water heater and the federal minimum uniform energy factor in force for that class at the date of manufacture"
+options:
+ min: 0.5
+ max: 4.0
+ step: 0.01
+default: derived
+```
+
+## Minimum coefficient of performance for heat pump equipment shall be as indicated in the datasheet.
+
+```datasheet
+label: Minimum Coefficient of Performance — Heat Pump Equipment
+type: range
+options:
+ min: 1.5
+ max: 5.0
+ step: 0.1
+```
+
+## A coefficient of performance is only comparable when the ambient air temperature, the entering water temperature, and the leaving water temperature it was measured at are stated with it. {note}
+
+## The Contractor shall submit the coefficient of performance of the selected heat pump equipment at the AHRI 1300 rating conditions and at the project's design entering water and ambient conditions.
+
+## Standby loss of each storage water heater shall not exceed the limit the applicable federal test procedure sets for its rated storage volume and input.
+
+# Storage Vessel Construction {toc}
+
+## Vessel Lining and Wetted Materials {toc}
+
+### The lining is the vessel's only corrosion barrier, and every lining trades initial cost against the water chemistry and maintenance regime it tolerates. {note}
+
+### The storage vessel lining shall be as indicated in the datasheet.
+
+```datasheet
+label: Storage Vessel Lining
+type: select
+options:
+ - "Glass-lined steel"
+ - "Cement-lined steel"
+ - "Copper-lined steel"
+ - "Stainless steel Type 316L"
+ - "Stainless steel Type 444"
+default: "Glass-lined steel"
+```
+
+### A fused porcelain enamel lining is inexpensive and durable on typical municipal supply, but it is never perfectly continuous, so it depends on cathodic protection to defend the steel at every pinhole and cut edge. {note}
+
+### Stainless linings need no anode and tolerate soft or aggressive water, but they are the materials that chloride attacks, so their limit is a chloride ceiling rather than a hardness or alkalinity one. {note}
+
+### Where a stainless steel vessel is selected, the Contractor shall confirm that the incoming water chloride concentration is below the concentration the vessel manufacturer publishes for the storage temperature setpoint.
+
+### A cement lining protects the steel by holding a high pH at the steel face, and it depends on staying wet to do so. {note}
+
+### A cement-lined vessel shall not be drained and left empty for longer than the vessel manufacturer permits.
+
+### The storage vessel working pressure rating shall be as indicated in the datasheet.
+
+```datasheet
+label: Storage Vessel Working Pressure Rating
+type: range
+unit: psi
+options:
+ min: 100
+ max: 300
+ setpoints: [100, 125, 150, 160, 200, 250, 300]
+default: 150
+```
+
+## Cathodic Protection {toc}
+
+### An anode is a deliberately sacrificial metal that corrodes in place of the steel; which anode is right follows from the lining and from the water it will sit in, not from a general preference. {note}
+
+### Cathodic protection shall be as indicated in the datasheet.
+
+```datasheet
+label: Cathodic Protection
+type: select
+derived: "the storage vessel lining selected and the chemistry of [[parameter: site-water-supply-source]]"
+options:
+ - "Magnesium sacrificial anode"
+ - "Aluminum-zinc sacrificial anode"
+ - "Impressed-current powered anode"
+ - "None because the vessel material requires no anode"
+default: derived
+```
+
+### Every vessel with a lining that depends on cathodic protection shall be furnished with at least one anode accessible from the vessel exterior.
+
+### Magnesium drives the most protective current and is consumed fastest; where sulfate-reducing bacteria are present in a low-turnover system it can also generate a hydrogen sulfide odor, and aluminum-zinc is the alloy used to avoid that. {note}
+
+### An impressed-current anode is powered rather than consumed, and where a vessel is genuinely inaccessible for anode replacement it removes a maintenance task the building would otherwise have to perform. {note}
+
+### Where an impressed-current anode is selected, its rectifier shall report loss of output to the monitoring interface specified in this standard.
+
+### Anodes shall be located so that one can be withdrawn and replaced without disconnecting any piping connected to the vessel.
+
+## Vessel Insulation {toc}
+
+### Vessel insulation shall be as indicated in the datasheet.
+
+```datasheet
+label: Storage Vessel Insulation
+type: select
+options:
+ - "Factory insulation at the federal standby loss minimum"
+ - "Factory insulation at an enhanced thermal resistance"
+ - "Factory insulation with a field-applied supplemental jacket"
+default: "Factory insulation at the federal standby loss minimum"
+```
+
+### Every storage vessel shall be factory-insulated and jacketed.
+
+### Field-applied insulation shall not be accepted in place of factory insulation on any vessel.
+
+### Where a vessel is installed in an unconditioned space, the Contractor shall apply a supplemental insulating jacket over the factory jacket, leaving every access cover, control, tapping, and nameplate reachable and legible.
+
+### Insulation of the piping connected to the equipment is the subject of [[sync/plumbing-insulation]]. {note}
+
+## Indirect-Fired Vessel Heat Exchanger {toc}
+
+### An indirect vessel places a heat transfer fluid on one side of a wall and potable water on the other, so the separation the wall provides is a code question about what that fluid is. {note}
+
+### Heat exchanger separation shall be as indicated in the datasheet.
+
+```datasheet
+label: Indirect Vessel Heat Exchanger Separation
+type: select
+derived: "the fluid the heating loop carries and the degree of separation the adopted plumbing code requires between potable water and that fluid"
+options:
+ - "Single-wall heat exchanger"
+ - "Double-wall vented heat exchanger"
+ - "Not applicable to the selected heater configuration"
+default: derived
+```
+
+### The heat exchanger coil shall be stainless steel or copper, sized for the design duty at the heating loop supply temperature and flow that [[sync/hydronic-piping]] delivers.
+
+### Each heating-loop connection to the vessel shall be provided with an isolation valve and a union or flange so the coil can be isolated and the vessel replaced without cutting the loop piping.
+
+### Where a solar or recovered-heat loop supplies the vessel, the vessel shall be provided with a high-temperature limit that interrupts that loop before the stored water exceeds the vessel's rated operating temperature.
+
+# Combustion Air and Venting {toc}
+
+## Combustion Air Supply {toc}
+
+### An appliance that draws combustion air from the room competes with every other exhaust in the building for that air, while a sealed appliance takes its own air from outside and is indifferent to room pressure. {note}
+
+### The combustion air supply shall be as indicated in the datasheet.
+
+```datasheet
+label: Combustion Air Supply
+type: select
+options:
+ - "Room air through openings sized per NFPA 54"
+ - "Room air through a dedicated outdoor air duct to the room"
+ - "Sealed combustion through separate air and vent pipes"
+ - "Sealed combustion through a concentric air and vent assembly"
+ - "Engineered mechanical combustion air interlocked with the burner"
+ - "Not applicable to the selected energy source"
+```
+
+### Combustion air openings, ducts, and engineered systems shall be sized in accordance with NFPA 54 or the adopted fuel gas code.
+
+### Where an engineered mechanical combustion air system is selected, the burner shall be interlocked to prove airflow before it fires and to shut down on loss of airflow.
+
+### Where a fuel-fired appliance draws combustion air from the room, the Contractor shall verify that the room does not go negative with respect to outdoors under the worst combination of exhaust the building can operate, and shall report a negative result before startup.
+
+## Vent Category and Material {toc}
+
+### Venting category classifies an appliance by two independent facts: whether the vent runs above or below atmospheric pressure, and whether the flue gas condenses in it. {note}
+
+### The vent category shall be as indicated in the datasheet.
+
+```datasheet
+label: Vent Category
+type: select
+derived: "the draft arrangement of the selected appliance and its combustion technology, classified under ANSI Z21.10.3 and NFPA 54"
+options:
+ - "Category I"
+ - "Category II"
+ - "Category III"
+ - "Category IV"
+ - "Not applicable to the selected energy source"
+default: derived
+```
+
+### Category I is negative pressure and non-condensing, Category II is negative pressure and condensing, Category III is positive pressure and non-condensing, and Category IV is positive pressure and condensing. {note}
+
+### The vent material shall be as indicated in the datasheet.
+
+```datasheet
+label: Vent Material
+type: select
+options:
+ - "Type B double-wall metal vent"
+ - "Type L vent listed to UL 641"
+ - "AL29-4C stainless steel"
+ - "Polypropylene listed to UL 1738"
+ - "PVC"
+ - "CPVC"
+ - "Not applicable to the selected energy source"
+```
+
+### The vent material shall be listed for the appliance's vent category and shall be a material the appliance manufacturer names in the installation instructions for the specific model furnished.
+
+### A positive-pressure vent is gas-tight by construction rather than by draft, so a material that is merely heat-resistant is not sufficient; it must also hold a sealed joint at the vent pressure the appliance produces. {note}
+
+### Unless the datasheet selects a plastic vent material, plastic shall not be used to vent a fuel-fired appliance under this standard.
+
+### Where the datasheet selects PVC or CPVC vent material, the Contractor shall obtain written confirmation from the Authority Having Jurisdiction that the material is accepted for the appliance before the vent is fabricated.
+
+### Some jurisdictions restrict plastic venting of gas-fired condensing appliances on the grounds of long-term durability and of flue gas temperature during an abnormal firing condition, and the stainless and polypropylene materials do not carry that exposure. {note}
+
+## Vent Arrangement and Termination {toc}
+
+### The vent arrangement shall be as indicated in the datasheet.
+
+```datasheet
+label: Vent Arrangement
+type: select
+options:
+ - "One vent serving one appliance"
+ - "A common vent serving multiple appliances of the same model"
+ - "A common vent with an engineered draft control system"
+ - "Not applicable to the selected energy source"
+```
+
+### Common vents shall be sized by the NFPA 54 vent tables or by an engineered method the vent or appliance manufacturer publishes for the configuration.
+
+### Appliances from different manufacturers shall not share a positive-pressure vent unless each manufacturer confirms the proposed configuration in writing.
+
+### Vent diameter, total equivalent length, fitting allowances, and termination clearances shall comply with the appliance manufacturer's installation instructions and with NFPA 54 or the adopted fuel gas code.
+
+### Vent and combustion air terminations shall be located as shown on [[drawing: the roof plan and exterior elevations]].
+
+### The Contractor shall verify that each termination clears building openings, air intakes, adjacent terminations, walking surfaces, grade, and the local snow accumulation depth by the distances the appliance manufacturer and the fuel gas code require, and shall report any conflict before the vent is fabricated.
+
+## Condensate from Condensing Equipment {toc}
+
+### Flue gas condensate from a gas-fired condensing appliance is acidic enough to attack cast iron, galvanized steel, and copper drainage, so it is neutralized before it enters a drainage system built from those materials. {note}
+
+### Condensate handling shall be as indicated in the datasheet.
+
+```datasheet
+label: Condensate Handling
+type: select
+options:
+ - "Neutralizer draining by gravity to an indirect waste receptor"
+ - "Neutralizer draining by gravity to a floor drain"
+ - "Neutralizer discharging through a condensate pump to an indirect waste receptor"
+ - "Direct discharge to an acid-resistant drainage system without neutralization"
+ - "Not applicable to the selected energy source"
+```
+
+### Unless the datasheet selects direct discharge to an acid-resistant drainage system, condensate from a condensing appliance shall pass through a neutralizer before it reaches the drainage system.
+
+### The neutralizer shall be furnished with replaceable media, sized for the condensate rate the appliance produces at full input, and installed so the media can be changed without cutting piping.
+
+### Condensate piping shall be PVC, CPVC, polypropylene, or stainless steel, and shall not be copper, brass, galvanized steel, or bare carbon steel.
+
+### Condensate piping shall be routed to fall continuously to the receptor.
+
+### Any condensate pump provided shall alarm on high level to the monitoring interface specified in this standard.
+
+### Condensate discharge shall terminate over the receptors shown on [[drawing: the plumbing plans]].
+
+# Fuel Gas Connection at the Equipment {toc}
+
+## Fuel gas piping upstream of the equipment connection is the subject of [[sync/fuel-gas-piping]]; this article covers only the train between that piping and the appliance. {note}
+
+## Each fuel-fired appliance shall be provided with a manual shutoff valve outside the appliance jacket and within sight of the appliance it serves.
+
+## Each fuel-fired appliance shall be provided with a sediment trap downstream of the manual shutoff valve and upstream of the appliance inlet.
+
+## Each fuel-fired appliance shall be provided with a union or flanged joint between the manual shutoff valve and the appliance so the appliance can be disconnected without cutting the gas piping.
+
+## Each fuel-fired appliance shall be provided with a pressure test port at the appliance inlet for combustion setup.
+
+## An at-heater gas pressure regulator shall be provided as indicated in the datasheet.
+
+```datasheet
+label: At-Heater Gas Pressure Regulator
+type: select
+derived: "the gas distribution pressure delivered to the appliance compared against the maximum inlet pressure the appliance is listed for"
+options:
+ - "Required"
+ - "Not required"
+ - "Not applicable to the selected energy source"
+default: derived
+```
+
+## Where a regulator is provided, its vent shall be piped to outdoors or the regulator shall be of a vent-limiting type listed for indoor installation.
+
+## Where the appliance is fired on fuel oil, the oil supply, tank, and burner installation shall comply with NFPA 31.
+
+# Heat Pump Water Heating Equipment {toc}
+
+## A heat pump moves heat from air or water into the stored water rather than generating it, which is why it delivers several units of heat per unit of electricity and why it cools and dries whatever it draws from. {note}
+
+## The heat pump source shall be as indicated in the datasheet.
+
+```datasheet
+label: Heat Pump Source
+type: select
+options:
+ - "Air drawn from and returned to the equipment room"
+ - "Air ducted from outdoors and returned outdoors"
+ - "Air ducted from outdoors and discharged into the equipment room"
+ - "Air drawn from a heat-rich interior space"
+ - "An outdoor split condensing unit serving an indoor vessel"
+ - "A building water loop or ground loop"
+ - "Recovered heat from a refrigeration or process system"
+ - "Not applicable to the selected energy source"
+```
+
+## Where the datasheet selects a source that draws from the equipment room, the room shall be large enough and ventilated so that the air entering the unit stays above the minimum entering air temperature the unit is rated for at the design condition.
+
+## Where the cooling effect of the unit would drive an adjacent occupied space or the equipment room outside its design conditions, ductwork shall be installed to draw source air from and discharge it to locations that do not.
+
+## Condensate produced by dehumidification of the source air shall be piped to a receptor, trapped as the unit manufacturer requires, and pitched to drain.
+
+## The refrigerant safety class shall be as indicated in the datasheet.
+
+```datasheet
+label: Heat Pump Refrigerant Safety Class
+type: select
+options:
+ - "A1 nonflammable"
+ - "A2L lower flammability"
+ - "A3 higher flammability"
+ - "B1 higher toxicity and nonflammable"
+ - "R-744 carbon dioxide operating transcritically"
+ - "Not applicable to the selected energy source"
+```
+
+## The installed refrigerant charge shall not exceed the charge limit UL 60335-2-40 permits for the refrigerant safety class and for the volume and ventilation of the space the equipment occupies.
+
+## Where the equipment uses a flammable refrigerant, the Contractor shall install the leak detection, ventilation, and mitigation provisions the equipment listing requires.
+
+## Leak detection alarm outputs shall be reported to the monitoring interface specified in this standard.
+
+## A transcritical carbon dioxide unit rejects heat across a gliding temperature rather than at a condensing plateau, so it produces high leaving water temperatures efficiently and loses efficiency when the water returning to it is already warm. {note}
+
+## Where a transcritical carbon dioxide unit is selected, the storage vessel and its piping shall be arranged to preserve thermal stratification and to return the coldest available water to the unit.
+
+## The supplemental heat source shall be as indicated in the datasheet.
+
+```datasheet
+label: Supplemental Heat Source
+type: select
+options:
+ - "None because the heat pump is sized for the full load"
+ - "Integral electric resistance elements"
+ - "A separate electric resistance heater"
+ - "A separate fuel-fired heater"
+ - "A boiler-fed coil in the storage vessel"
+ - "Not applicable to the selected energy source"
+```
+
+## Where a supplemental heat source is provided, its controls shall lock it out above an adjustable outdoor or source-air temperature so that it does not displace heat pump operation during normal conditions.
+
+## Maximum sound level shall be as indicated in the datasheet.
+
+```datasheet
+label: Heat Pump Maximum Sound Level at 3 ft
+type: range
+unit: dBA
+options:
+ min: 35
+ max: 80
+ step: 1
+```
+
+## A heat pump water heater runs a compressor and a fan continuously through a recovery cycle, so it is audible in a way that a storage heater in the same room is not. {note}
+
+# Electrical Connection at the Equipment {toc}
+
+## Electrical work upstream of the disconnecting means is the subject of the electrical standards; this article covers the connection requirements the equipment itself imposes. {note}
+
+## Supply voltage shall be as indicated in the datasheet.
+
+```datasheet
+label: Supply Voltage
+type: range
+unit: V
+drawing_ref: "the plumbing equipment schedule"
+options:
+ min: 120
+ max: 600
+ setpoints: [120, 208, 240, 277, 347, 480, 600]
+default: deferred
+```
+
+## Supply phase shall be as indicated in the datasheet.
+
+```datasheet
+label: Supply Phase
+type: select
+drawing_ref: "the plumbing equipment schedule"
+options:
+ - "1Φ"
+ - "3Φ"
+default: deferred
+```
+
+## The disconnecting means shall be as indicated in the datasheet.
+
+```datasheet
+label: Disconnecting Means
+type: select
+options:
+ - "A non-fused disconnect switch within sight of the equipment"
+ - "A fused disconnect switch within sight of the equipment"
+ - "A lockable branch-circuit breaker within sight of the equipment"
+ - "A cord and plug connection"
+default: "A non-fused disconnect switch within sight of the equipment"
+```
+
+## Each item of equipment furnished under this standard shall be provided with a disconnecting means meeting NFPA 70 for the type of load it serves.
+
+## Branch-circuit conductors, overcurrent protection, and the disconnecting means rating shall match the nameplate values of the equipment actually furnished.
+
+## The Contractor shall report any difference between those nameplate values and the scheduled electrical characteristics before rough-in.
+
+## Equipment grounding and bonding shall comply with [[sync/grounding-and-bonding]].
+
+## Where a dielectric fitting or a non-metallic piping section interrupts the metallic path at the equipment, a bonding jumper shall be installed across it so the hot and cold water piping remains electrically continuous.
+
+# Temperature Setpoints and Legionella Control {toc}
+
+## Storage and Delivery Temperatures {toc}
+
+### Legionella multiplies between roughly 68°F and 122°F, is progressively inactivated above that band, and is killed within minutes near 140°F, which is why stored water is held hot and blended down rather than stored at the temperature people touch. {note}
+
+### The storage temperature setpoint shall be as indicated in the datasheet.
+
+```datasheet
+label: Storage Temperature Setpoint
+type: range
+unit: °F
+options:
+ min: 120
+ max: 180
+ setpoints: [120, 125, 130, 135, 140, 145, 150, 160, 170, 180]
+default: 140
+```
+
+### The delivered distribution temperature setpoint shall be as indicated in the datasheet.
+
+```datasheet
+label: Delivered Distribution Temperature Setpoint
+type: range
+unit: °F
+options:
+ min: 105
+ max: 140
+ setpoints: [105, 110, 115, 120, 124, 130, 135, 140]
+default: 120
+```
+
+### Where the datasheet sets a storage temperature below the temperature at which stored water is thermally disinfected, the water management program shall specify the compensating control the project relies on.
+
+### The Contractor shall install the equipment that the specified compensating control requires.
+
+### The minimum recirculation return temperature shall be as indicated in the datasheet.
+
+```datasheet
+label: Minimum Recirculation Return Temperature
+type: range
+unit: °F
+derived: "the delivered distribution temperature setpoint less the loop temperature drop the water management program permits"
+options:
+ min: 100
+ max: 135
+ setpoints: [100, 105, 110, 115, 120, 124, 130, 135]
+default: derived
+```
+
+### The return temperature is the only measurement that reports what the far end of the loop is actually doing, because it is the water that has travelled the whole loop and come back. {note}
+
+### The thermal disinfection capability shall be as indicated in the datasheet.
+
+```datasheet
+label: Thermal Disinfection Capability
+type: select
+options:
+ - "None"
+ - "A manual elevated-temperature flush procedure documented in the operating manual"
+ - "An automatic scheduled elevated-temperature cycle through the mixing station"
+```
+
+### Where an automatic elevated-temperature cycle is provided, it shall be interlocked so that water above the delivered distribution temperature setpoint cannot reach a fixture while the cycle is running unless the fixture is isolated.
+
+## Master Mixing Valve {toc}
+
+### A master mixing valve lets the system store water hot enough to control Legionella and still deliver water at a temperature that does not scald, which is the reason both setpoints can be met at once. {note}
+
+### The master mixing valve type shall be as indicated in the datasheet.
+
+```datasheet
+label: Master Mixing Valve Type
+type: select
+options:
+ - "A thermostatic valve listed to ASSE 1017"
+ - "An electronic mixing station listed to ASSE 1017"
+ - "None because the equipment stores and delivers at the same temperature"
+default: "A thermostatic valve listed to ASSE 1017"
+```
+
+### The master mixing valve arrangement shall be as indicated in the datasheet.
+
+```datasheet
+label: Master Mixing Valve Arrangement
+type: select
+options:
+ - "A single valve covering the full design flow range"
+ - "Valves in parallel with sequenced isolation for extended turndown"
+ - "Duplex valves with one held as a standby"
+```
+
+### The master mixing valve body material shall be as indicated in the datasheet.
+
+```datasheet
+label: Master Mixing Valve Body Material
+type: select
+options:
+ - "Bronze"
+ - "Dezincification-resistant brass"
+ - "Stainless steel"
+default: "Bronze"
+```
+
+### The master mixing valve shall hold its outlet temperature within the accuracy band it is listed to across the whole range from the design peak flow down to the recirculation-only flow the system sees at night.
+
+### A valve sized for the peak draw alone loses control at the low overnight flow, which lets the loop drift toward the stored temperature and, on a valve without a positive low-flow shutoff, can deliver stored-temperature water to a fixture. {note}
+
+### Where a single valve cannot hold its accuracy band across that full range, valves shall be piped in parallel and sequenced so that the smaller valve alone serves the low-flow condition.
+
+### The master mixing valve shall be installed with isolation valves, integral or separate checks on the hot and cold inlets, a strainer on each inlet, and unions or flanges permitting removal without cutting piping.
+
+### The master mixing valve shall be furnished with a means of locking or sealing the setpoint after commissioning.
+
+## Downstream Temperature Limiting {toc}
+
+### The scope of downstream temperature limiting shall be as indicated in the datasheet.
+
+```datasheet
+label: Downstream Temperature Limiting Scope
+type: select
+derived: "the delivered distribution temperature setpoint compared against the fixture delivery temperature limits the adopted plumbing code imposes on the fixtures served"
+options:
+ - "Every fixture that delivers water to a user"
+ - "Only the fixtures for which the adopted plumbing code requires a limiting device"
+ - "None because the delivered distribution temperature is at or below every applicable fixture limit"
+default: derived
+```
+
+### Fixtures requiring a delivery temperature below the distribution setpoint shall be served by a device listed to ASSE 1070 at the fixture or at the fixture group.
+
+### Showers and tub-shower combinations shall be served by a compensating valve listed to ASSE 1016 in addition to any upstream limiting device.
+
+### Plumbed emergency eyewash and drench equipment shall be served by a valve listed to ASSE 1071 rather than by a device listed to ASSE 1070.
+
+### Selection and installation of the fixture-mounted devices themselves is the subject of [[sync/plumbing-fixtures]]. {note}
+
+# Thermal Expansion Control {toc}
+
+## Water expands about two percent when heated from a cold inlet temperature to a storage setpoint, and in a system closed by a check valve that volume has nowhere to go, so pressure climbs until the relief valve opens. {note}
+
+## Repeated relief discharge from thermal expansion erodes the relief valve seat, and a valve that has been cycled that way is the one that fails to reseat and then fails to open when it is genuinely needed. {note}
+
+## Thermal expansion control shall be as indicated in the datasheet.
+
+```datasheet
+label: Thermal Expansion Control
+type: select
+derived: "whether the cold water service to the building contains a check valve, backflow preventer, or pressure reducing valve that closes the system to the utility main"
+options:
+ - "A diaphragm or bladder expansion vessel"
+ - "A stainless steel bellows expansion vessel"
+ - "A thermal expansion relief valve discharging to a receptor"
+ - "None because the system remains open to the utility main"
+default: derived
+```
+
+## Whether the building water service contains a check valve, a backflow assembly, or a pressure reducing valve is determined by [[sync/backflow-prevention]] and by the utility's requirements, and it is that determination rather than a project preference that decides whether expansion control is needed. {note}
+
+## The expansion vessel bladder material shall be as indicated in the datasheet.
+
+```datasheet
+label: Expansion Vessel Bladder Material
+type: select
+options:
+ - "Butyl"
+ - "Polypropylene-lined butyl"
+ - "Stainless steel bellows"
+default: "Butyl"
+```
+
+## The expansion vessel acceptance volume shall be as indicated in the datasheet.
+
+```datasheet
+label: Expansion Vessel Acceptance Volume
+type: range
+unit: gal
+derived: "the system water volume, the rise from [[parameter: site-water-supply-temperature-minimum]] to the storage temperature setpoint, and the system static and relief pressures"
+options:
+ min: 0.5
+ max: 200
+ setpoints: [0.5, 1, 2, 4.4, 8.5, 14, 20, 32, 44, 62, 80, 120, 200]
+default: derived
+```
+
+## The expansion vessel shall be installed on the cold water supply to the water heater, upstream of the heater inlet and downstream of the device that closes the system.
+
+## The Contractor shall measure the system static pressure at the vessel's installed elevation and shall set the vessel pre-charge to that pressure before the vessel is connected to the water side.
+
+## The Contractor shall record the measured static pressure and the pre-charge as set in the startup report.
+
+## Setting the pre-charge after the vessel is connected reads the water-side pressure rather than the air-side pressure and leaves the vessel with the wrong charge, which is why the sequence is specified rather than left to the installer. {note}
+
+# Temperature and Pressure Relief {toc}
+
+## Each fired storage water heater and each indirect storage vessel shall be provided with a combined temperature and pressure relief valve listed to ANSI Z21.22.
+
+## The relief valve set pressure shall be as indicated in the datasheet.
+
+```datasheet
+label: Relief Valve Set Pressure
+type: range
+unit: psi
+derived: "the working pressure rating of the storage vessel the valve protects"
+options:
+ min: 75
+ max: 300
+ setpoints: [75, 100, 125, 150, 160, 200, 250, 300]
+default: derived
+```
+
+## The relief valve set temperature shall be 210°F.
+
+## The relief valve relieving capacity in Btu/h shall equal or exceed the input rating of the equipment it protects.
+
+## The relief valve shall be installed in a tapping the vessel manufacturer designates for it, positioned so its temperature element is immersed in the upper portion of the stored water.
+
+## No valve, restriction, or reduction in size shall be installed between the vessel and the relief valve inlet.
+
+## The relief discharge piping material shall be as indicated in the datasheet.
+
+```datasheet
+label: Relief Discharge Piping Material
+type: select
+options:
+ - "Copper Type L"
+ - "CPVC"
+ - "Galvanized steel"
+ - "Stainless steel"
+default: "Copper Type L"
+```
+
+## Relief discharge piping shall be the full size of the relief valve outlet over its entire length.
+
+## Relief discharge piping shall be rated for 210°F.
+
+## Relief discharge piping shall fall continuously from the valve to its point of termination.
+
+## Relief discharge piping shall terminate through an air gap over a receptor placed where a discharge is visible to operating staff.
+
+## Relief discharge piping shall not be trapped, valved, or threaded at its outlet end.
+
+## Relief discharge tubes and their fittings shall comply with ASME A112.4.1.
+
+# Hot Water Delivery and Recirculation {toc}
+
+## Delivery Method {toc}
+
+### Water standing in a branch cools toward room temperature and sits in the band Legionella favors, so the design question is how hot water is kept close to the fixture rather than whether the fixture eventually gets it. {note}
+
+### The hot water delivery method shall be as indicated in the datasheet.
+
+```datasheet
+label: Hot Water Delivery Method
+type: select
+options:
+ - "A pumped recirculation return loop"
+ - "Electric heat tracing on the distribution piping without a return loop"
+ - "Neither, because every branch is within the maximum length the adopted code allows"
+```
+
+### Where heat tracing is selected, the cable, controls, and installation are the subject of [[sync/electric-heat-tracing]]. {note}
+
+### The recirculation return connection point shall be as indicated in the datasheet.
+
+```datasheet
+label: Recirculation Return Connection Point
+type: select
+options:
+ - "A dedicated return tapping on the water heater"
+ - "A dedicated return tapping on the storage vessel"
+ - "The cold water inlet piping upstream of the water heater"
+ - "Not applicable to the selected delivery method"
+```
+
+### Returning the loop to the cold inlet mixes warm return water with incoming cold water and raises the temperature the heater sees, which reduces the recovery a condensing appliance achieves because its flue gas no longer condenses against the entering water. {note}
+
+### Where the datasheet selects a return to the cold water inlet piping and the heater is a condensing appliance, the Contractor shall obtain the appliance manufacturer's written confirmation that the arrangement does not void the appliance warranty.
+
+### The recirculation loop and its return main are the subject of [[sync/domestic-water-piping]]; this article governs the pump, its control, and the devices that balance the loop. {note}
+
+## Recirculation Pump {toc}
+
+### The recirculation design flow rate shall be as indicated in the datasheet.
+
+```datasheet
+label: Recirculation Design Flow Rate
+type: range
+unit: GPM
+drawing_ref: "the plumbing equipment schedule"
+options:
+ min: 0.5
+ max: 200
+ setpoints: [0.5, 1, 2, 3, 5, 8, 12, 20, 30, 50, 75, 100, 150, 200]
+default: deferred
+```
+
+### The recirculation pump motor type shall be as indicated in the datasheet.
+
+```datasheet
+label: Recirculation Pump Motor Type
+type: select
+options:
+ - "A wet-rotor permanent-magnet electronically commutated motor"
+ - "A wet-rotor fixed-speed induction motor"
+ - "A close-coupled inline pump with a separate motor"
+```
+
+### The recirculation pump wetted material shall be as indicated in the datasheet.
+
+```datasheet
+label: Recirculation Pump Wetted Material
+type: select
+options:
+ - "Bronze"
+ - "Stainless steel"
+ - "Engineered polymer"
+default: "Bronze"
+```
+
+### The recirculation pump shall be selected to deliver the scheduled flow at the loop head loss with the operating point on a stable portion of its curve.
+
+### The recirculation pump shall be installed with an isolation valve on suction and discharge, a check valve on the discharge, unions or flanges permitting removal, and a strainer on the suction where the pump manufacturer requires one.
+
+### The recirculation pump motor shall be rated for continuous duty and shall be suited to the temperature and humidity of the space it is installed in.
+
+### Motors furnished under this standard shall comply with [[sync/electric-motors]].
+
+## Recirculation Control {toc}
+
+### A pump that runs continuously against a loop already at temperature spends energy pushing heat out of the pipe insulation, which is the loss the energy codes address by requiring the pump to stop. {note}
+
+### The recirculation pump control shall be as indicated in the datasheet.
+
+```datasheet
+label: Recirculation Pump Control
+type: select
+options:
+ - "An aquastat sensing return temperature"
+ - "A time schedule"
+ - "An aquastat sensing return temperature with a time schedule"
+ - "Demand initiation at the fixture"
+ - "Scheduled operation from the building automation system with temperature feedback"
+ - "Continuous operation"
+default: "An aquastat sensing return temperature with a time schedule"
+```
+
+### Except where the datasheet selects continuous operation, the recirculation pump control shall stop the pump when the loop is at temperature.
+
+### Except where the datasheet selects continuous operation, the recirculation pump control shall stop the pump outside the building's occupied schedule.
+
+### The aquastat shall start the pump on falling return temperature at an adjustable setpoint not lower than the minimum recirculation return temperature indicated in the datasheet.
+
+### A schedule that shuts a loop down overnight lets the loop cool into the Legionella growth band until morning, and where the water management program does not accept that exposure the program specifies continuous or more frequent circulation instead. {note}
+
+### Where the water management program requires the loop to be held above a temperature at all hours, the time schedule shall be configured to keep the pump enabled at all hours.
+
+### The Contractor shall record that schedule configuration in the closeout submittals.
+
+## Recirculation Balancing {toc}
+
+### Flow in an unbalanced return circuit follows the path of least resistance, so the short branches circulate freely while the long ones, which are the branches most at risk of cooling, get almost nothing. {note}
+
+### The recirculation balancing method shall be as indicated in the datasheet.
+
+```datasheet
+label: Recirculation Balancing Method
+type: select
+options:
+ - "A manual balancing valve with a memory stop at each branch"
+ - "A self-actuating thermostatic balancing valve at each branch"
+ - "A pressure-independent automatic balancing valve at each branch"
+ - "None because the loop has no branch returns"
+```
+
+### A balancing device shall be provided at the base of each riser return and at each branch return so that circulation in every branch is proportional to that branch's heat loss.
+
+### The Contractor shall coordinate the balancing device locations with the riser and branch arrangement shown on [[drawing: the plumbing riser diagrams]].
+
+### The Contractor shall balance the recirculation system after the loop has reached its operating temperature.
+
+### The Contractor shall record the flow or the return temperature achieved at each balancing device.
+
+### The Contractor shall set and lock the memory stop on each balancing device that has one.
+
+### Balancing valves shall be installed with a means of measuring the temperature of the branch return immediately upstream of each device.
+
+# Equipment Controls and Monitoring {toc}
+
+## Each water heater shall be furnished with the operating control, high-temperature limit, and combustion or thermal safety controls its listing requires for its class.
+
+## Each water heater fired automatically and requiring a low-water cutoff under the adopted code shall be furnished with one, interlocked to prevent firing on low water.
+
+## The factory-furnished control package shall not be modified, bypassed, or defeated.
+
+## Any field-furnished control shall be external to the appliance and shall not override a safety function.
+
+## The equipment monitoring interface shall be as indicated in the datasheet.
+
+```datasheet
+label: Equipment Monitoring Interface
+type: select
+options:
+ - "None because the equipment operates on local controls only"
+ - "Hardwired alarm and status contacts to the building automation system"
+ - "A network interface reporting status and temperatures"
+ - "A network interface reporting status and temperatures and accepting setpoint changes"
+ - "A network interface providing full access to setpoints, sequences, and diagnostics"
+```
+
+## The points reported to the monitoring interface shall be as indicated in the datasheet.
+
+```datasheet
+label: Monitored Points
+type: checkbox
+options:
+ - "Storage temperature"
+ - "Delivered temperature downstream of the mixing valve"
+ - "Recirculation return temperature"
+ - "Recirculation pump run status"
+ - "Water heater run status"
+ - "Water heater fault or lockout alarm"
+ - "Condensate pump high level alarm"
+ - "Impressed-current anode rectifier fault"
+ - "Refrigerant leak detection alarm"
+```
+
+## The points a water management program depends on are the ones it will be audited against, so the temperatures that prove the program is working are monitored rather than merely set. {note}
+
+## Temperature points reported to the monitoring interface shall be sensed by a sensor installed in a thermowell in the flowing stream, not by a sensor strapped to the outside of a pipe.
+
+## Each monitored temperature sensor shall be verified at startup against a traceable reference and shall read within ±2°F of it.
+
+## Network points, addressing, and the communication protocol shall be coordinated with [[sync/building-automation-system]].
+
+# Installation {toc}
+
+## Equipment Setting and Anchorage {toc}
+
+### The equipment support shall be as indicated in the datasheet.
+
+```datasheet
+label: Equipment Support
+type: select
+options:
+ - "A concrete housekeeping pad"
+ - "A structural steel stand or platform"
+ - "The finished floor slab"
+ - "A wall-mounted bracket furnished by the equipment manufacturer"
+ - "A frame suspended from the structure"
+```
+
+### Equipment shall be set level, fully bearing on its support, and shimmed only with corrosion-resistant shims where leveling is required.
+
+### The seismic anchorage shall be as indicated in the datasheet.
+
+```datasheet
+label: Seismic Anchorage
+type: select
+derived: "[[parameter: seismic-design-category]] and the component importance factor the project assigns to domestic hot water service"
+options:
+ - "None required"
+ - "Strap anchorage to adjacent structure"
+ - "A pre-approved anchorage detail listed by an evaluation agency"
+ - "Project-specific anchorage engineered for the installation"
+default: derived
+```
+
+### Anchorage shall resist the seismic forces ASCE 7 assigns to the component.
+
+### Where anchorage is engineered for the project, the anchorage design shall be sealed by a registered design professional licensed in the project's jurisdiction.
+
+### Where a pre-approved anchorage detail is used, it shall be a detail listed for the equipment weight, geometry, and mounting condition actually installed.
+
+### Anchorage details, isolation, and restraint hardware shall comply with [[sync/vibration-isolation-and-seismic-restraint]].
+
+### Anchorage shall not bear on the vessel jacket or insulation in a way that crushes it.
+
+### Any spacer required to prevent that bearing shall be furnished by the vessel manufacturer or cut from a material the vessel manufacturer accepts.
+
+## Water Piping Connections at the Equipment {toc}
+
+### The cold inlet, hot outlet, and recirculation return connections shall each be made with a union through 2 in. and with a flanged or grooved connection at 2-1/2 in. and larger, so the equipment can be removed without cutting the building piping.
+
+### Each equipment water connection shall be provided with an isolation valve.
+
+### A dielectric fitting shall be installed wherever a copper or bronze equipment connection meets ferrous building piping.
+
+### Each storage vessel shall be provided with a full-port ball valve at its drain tapping, fitted with a hose-thread outlet and a threaded cap.
+
+### The Contractor shall confirm before setting the equipment that the drain connection and the receptor together permit a complete drain-down without flooding the room.
+
+### Piping shall be supported independently of the equipment so that no piping weight or thermal movement is carried by an equipment connection.
+
+## Gauges, Thermometers, and Identification {toc}
+
+### Each water heater shall be provided with a pressure gauge on its cold inlet and a combination pressure and temperature gauge on its hot outlet.
+
+### A thermometer shall be provided on the mixing valve outlet and on the recirculation return immediately upstream of its connection to the equipment.
+
+### Gauges and thermometers shall be positioned so they can be read from the front of the equipment without removing a cover or a shield.
+
+### Each water heater, storage vessel, mixing valve, expansion vessel, recirculation pump, and isolation valve shall carry a permanent tag giving the equipment identifier from the schedule, the service, and the setpoint where the item has one.
+
+### Tag numbering shall match the as-built piping schematic so that any tagged device can be located from the schematic and any device in the field can be found on it.
+
+### Pipe and valve identification shall comply with [[sync/plumbing-piping-identification]].
+
+# Startup and Field Testing {toc}
+
+## Pre-Startup Verification {toc}
+
+### The Contractor shall verify before startup that the equipment is piped with the inlet and outlet in the correct connections, that all isolation valves are open, and that the vessel is filled and vented of air.
+
+### The Contractor shall verify before startup that the relief valve is installed in its designated tapping and that its discharge piping is complete, unobstructed, and terminated over a receptor.
+
+### The Contractor shall verify before startup that the expansion vessel pre-charge has been set against the measured static pressure.
+
+### The Contractor shall verify before startup that the static fuel gas supply pressure at the appliance inlet is within the listed range for the appliance.
+
+### The Contractor shall verify before startup that the vent system is complete, unobstructed, correctly supported, and terminated as specified.
+
+### The Contractor shall verify before startup that the condensate drain is open and routed to its receptor and that any neutralizer contains fresh media.
+
+### The Contractor shall verify before startup that the electrical supply matches the equipment nameplate and that the disconnecting means is installed and accessible.
+
+## Startup {toc}
+
+### Startup shall be performed by a technician qualified under this standard for the equipment class being started.
+
+### Startup of a fuel-fired appliance shall include measurement of the dynamic gas supply pressure at the appliance inlet with the appliance at full input.
+
+### Startup of a fuel-fired appliance shall include setting the manifold pressure and performing a combustion test at high fire and at the lowest stable firing rate, recording carbon monoxide, carbon dioxide or oxygen, stack temperature, and combustion efficiency at each rate.
+
+### Startup shall include verification of the high-temperature limit by a simulated overtemperature condition.
+
+### Startup shall include verification of the relief valve by operation of its test lever, followed by confirmation that the valve reseats without leakage.
+
+### Startup shall include verification of recirculation pump rotation, flow, and control response.
+
+### Startup shall include setting the storage temperature, the mixing valve outlet temperature, and the recirculation control setpoints, and recording each as found and as left.
+
+## Field Performance Test {toc}
+
+### The field performance test shall be conducted after startup, after the recirculation system has been balanced, and with the building water system filled and disinfected.
+
+### The field performance test shall verify the items indicated in the datasheet.
+
+```datasheet
+label: Field Performance Test Documentation
+type: checkbox
+options:
+ - "Outlet temperature at the water heater after a recovery cycle"
+ - "Delivered temperature downstream of the mixing valve at design flow"
+ - "Delivered temperature downstream of the mixing valve at recirculation-only flow"
+ - "Recirculation return temperature at the equipment"
+ - "Return temperature at each balancing device"
+ - "Relief valve manual test and reseat"
+ - "Combustion test results at high and low fire"
+ - "Heat pump capacity and condensate verification"
+ - "Expansion vessel pre-charge against measured static pressure"
+ - "Monitored point verification against a traceable reference"
+```
+
+### The field performance test shall verify the water heater outlet temperature within ±5°F of the storage temperature setpoint after a recovery cycle following a full draw-down.
+
+### The field performance test shall verify the delivered temperature downstream of the mixing valve within ±5°F of the delivered distribution temperature setpoint at the design flow and again at a draw representing overnight recirculation-only operation.
+
+### The field performance test shall verify that the recirculation return temperature at the equipment is at or above the minimum recirculation return temperature indicated in the datasheet.
+
+### The field performance test shall verify that the relief valve does not discharge during a recovery cycle from a full draw with the expansion control in service.
+
+### The field performance test shall verify that combustion results fall within the range the appliance manufacturer publishes.
+
+### The field performance test shall verify heat pump heating capacity within 90 percent of the published capacity at the measured test conditions, with no standing condensate inside the equipment cabinet.
+
+### Where a test result falls outside a specified tolerance, the Contractor shall correct the cause and retest at no cost to the Owner.
+
+### Where the parties disagree whether an observed condition constitutes a failed result, the Engineer of Record shall make the initial determination.
+
+### Commissioning activities beyond this test are the subject of [[sync/commissioning]]. {note}
+
+## Disinfection Before Use {toc}
+
+### The water heater and every storage vessel shall be disinfected together with the building domestic water system before the system is placed in potable service, in accordance with [[sync/disinfection-of-water-systems]].
+
+### The Contractor shall confirm that the disinfectant concentration and contact time used are within the limits the vessel and mixing valve manufacturers publish for their wetted materials.
+
+# Delivery, Storage, and Handling {toc}
+
+## Equipment shall be delivered in the manufacturer's packaging with factory covers, plugs, and tags in place.
+
+## The Contractor shall inspect equipment for shipping damage on arrival at the site.
+
+## The Contractor shall report shipping damage in writing to the carrier and to the equipment manufacturer before the damaged item is installed.
+
+## Damaged equipment shall not be installed until the manufacturer confirms in writing that the damage does not affect its performance, listing, or warranty.
+
+## Equipment shall be stored indoors on level dunnage, above freezing, and protected from weather, construction water, and physical damage until it is installed.
+
+## Insulated vessels and packaged heaters shall not be stacked.
+
+## Equipment containing refrigerant shall be stored and transported in the orientation the manufacturer permits.
+
+## Tipping a refrigerant-charged unit outside its permitted orientation moves compressor oil into the refrigerant circuit, and the unit then needs an extended settling period upright before it can be energized. {note}
+
+## Where a refrigerant-charged unit has been tipped outside its permitted orientation, it shall be stood upright for the settling period the manufacturer specifies before it is energized.
+
+## The Contractor shall record the settling period observed before the unit was energized.
+
+## Vent components, condensate components, gas train components, and controls shall be stored in their packaging, segregated from other trades' materials, and protected from dust and traffic.
+
+## Open pipe and vent ends shall be capped until the connection is made.
+
+# Warranty {toc}
+
+## The Contractor shall procure equipment carrying at least the warranty coverage indicated in the datasheet.
+
+## The Contractor shall furnish evidence of that coverage in the closeout submittals.
+
+```datasheet
+label: Warranty Period — Storage Vessel or Heat Exchanger
+type: range
+unit: yr
+options:
+ min: 1
+ max: 20
+ setpoints: [1, 3, 5, 6, 8, 10, 12, 15, 20]
+```
+
+```datasheet
+label: Warranty Period — Parts and Labor
+type: range
+unit: yr
+options:
+ min: 1
+ max: 10
+ setpoints: [1, 2, 3, 5, 7, 10]
+```
+
+## Where the datasheet indicates no warranty period, the equipment shall carry the standard published warranty for its class.
+
+## Where the equipment carries the standard published warranty, the Contractor shall state that period in the closeout submittals.
+
+## The warranty period shall begin at substantial completion or at the date of beneficial use by the Owner, whichever is earlier.
+
+## Where a warranted component is repaired or replaced, the repaired or replaced component shall carry a fresh full warranty term running from the date of the repair, or the remainder of the original term, whichever ends later.
+
+## The Contractor shall bear the cost of removing and reinstalling adjacent work required to reach a component being repaired under warranty.
+
+## The Contractor shall record the condition of that adjacent work before it is disturbed and shall restore it to the recorded condition.
+
+## Warranty coverage shall not be voided by water chemistry within the limits the equipment manufacturer publishes.
+
+## Where the Owner requires the equipment to operate on water outside those published limits, the Owner and the Engineer of Record shall record that condition and the treatment provided in the contract documents.
+
+# Spare Parts {toc}
+
+## The Contractor shall deliver the spare parts indicated in the datasheet to the Owner at substantial completion, each marked with the identifier of the equipment it serves and stored together in a labeled container in the equipment room or in a location the Owner designates.
+
+- one set of replacement gaskets for each unique equipment and mixing valve connection
+- one sacrificial anode for each vessel fitted with one
+- one relief valve for each unique combination of set pressure and outlet size
+- one pump cartridge or replacement pump head for each unique wet-rotor pump model
+- one replaceable bladder assembly for each unique expansion vessel model that has a field-replaceable bladder
+- one aquastat or temperature controller for each unique model
+- one media charge for each condensate neutralizer
+- one set of replacement inlet strainer screens for the mixing valve and the recirculation pump
+
+```datasheet
+label: Spare Parts Delivery
+type: checkbox
+options:
+ - "Connection gasket sets"
+ - "Sacrificial anodes"
+ - "Relief valves"
+ - "Pump cartridges or replacement pump heads"
+ - "Expansion vessel bladder assemblies"
+ - "Aquastats or temperature controllers"
+ - "Condensate neutralizer media charges"
+ - "Inlet strainer screens"
+```
+
+## The Contractor shall obtain the Owner's signed receipt for the spare parts delivered.