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SynC · SynC Standards

Commercial Water Heaters

Rev5
IssuedAug 29, 2026
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1 Scope

NOTE 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. (1.1)
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. (1.2)
NOTE The following are governed elsewhere and are outside this standard: (1.3)
  • 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
1.4 The Contractor shall install water heating equipment in the locations shown on the plumbing plans.
1.5 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.
1.6 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.
NOTE This standard establishes the temperature setpoints, mixing arrangements, monitoring points, and recirculation requirements at the equipment that a building water management program depends on. (1.7)
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. (1.8)

2 Referenced Standards

2.1 Equipment, materials, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited.
2.2 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.
2.3 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)

3 Submittals

3.1 Action Submittals

3.1.1 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
Action Submittal Packagecheckbox
☐ 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
3.1.2 Fabrication and installation of water heating equipment shall not begin until the corresponding action submittals have been reviewed and returned.

3.2 Informational Submittals

3.2.1 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
Informational Submittal Packagecheckbox
☐ 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

3.3 Closeout Submittals

3.3.1 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
Closeout Submittal Packagecheckbox
☐ 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

4 Quality Assurance

4.1 Installer and Startup Qualifications

4.1.1 Each portion of the installation shall be performed by personnel holding the license the Authority Having Jurisdiction requires for that trade.
4.1.2 Startup shall be performed by a technician certified by the equipment manufacturer wherever the manufacturer conditions the warranty on a factory-authorized startup.
4.1.3 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.
4.1.4 Refrigerant circuits shall be opened, charged, and serviced only by a technician certified under 40 CFR Part 82 Subpart F.
4.1.5 The Contractor shall have the required certifications on site and available for inspection before startup begins.

4.2 Product Listing and Certification

4.2.1 Each water heater shall bear the certification mark of a Nationally Recognized Testing Laboratory for the product safety standard that applies to its class.
4.2.2 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.
4.2.3 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.
4.2.4 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.

4.3 Pressure Vessel Construction

NOTE 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. (4.3.1)
4.3.2 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.
4.3.3 An unfired storage vessel exceeding the same limits shall be constructed and stamped to ASME Boiler and Pressure Vessel Code Section VIII Division 1.
4.3.4 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.
4.3.5 Storage volume shall not be reduced below the volume the load calculation calls for in order to stay under a pressure vessel construction limit.

5 Service Conditions at the Equipment

5.1 Equipment Room Conditions

5.1.1 The equipment room shall be maintained above freezing throughout the year.
5.1.2 Any portion of the equipment, relief piping, or condensate piping that passes through a space subject to freezing shall be freeze-protected.
5.1.3 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.
5.1.4 Where no gravity receptor can be provided, a sump with a duplex pump shall be provided.
5.1.5 The sump shall alarm on high level to the monitoring interface specified in this standard.
NOTE 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. (5.1.6)
5.1.7 Fuel-fired equipment shall be derated for AltitudeAltitudeParameterEach project supplies its own value.altitude in accordance with the equipment manufacturer's published high-altitude data, or in accordance with NFPA 54 where the manufacturer publishes none.

5.2 Incoming Water Chemistry

NOTE 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. (5.2.1)
5.2.2 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.
5.2.3 Scale control at the equipment shall be provided as indicated in the datasheet.
Scale Control at the Equipmentselect
None
Softened supply to the water heater
Blended softened and unsoftened supply to the water heater
Template-assisted crystallization scale inhibitor
Sequestering chemical feed
Derived — Site Water Supply HardnessSite Water Supply HardnessParameterEach project supplies its own value.site-water-supply-hardness evaluated against the maximum hardness the selected equipment is published to tolerate at the storage temperature setpoint (by default)
NOTE Softening, filtration, and chemical feed equipment upstream of the water heater is the subject of Domestic Water Softeners And FiltrationDomestic Water Softeners and FiltrationResolves to the current adopted revision.sync/domestic-water-softeners-and-filtration. (5.2.4)
5.2.5 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.

5.3 Service and Replacement Clearances

5.3.1 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.
5.3.2 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.
5.3.3 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.
5.3.4 The equipment shall be set so that the largest single component requiring replacement can be removed from the room without dismantling permanent building construction.

6 Energy Source and Heater Configuration

NOTE 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. (6.1)
6.2 The energy source that heats the domestic water shall be as indicated in the datasheet.
Domestic Hot Water Energy Sourceselect
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
6.3 Where the datasheet selects natural gas as the energy source, the Contractor shall confirm that Site Natural Gas ServiceSite Natural Gas ServiceParameterEach project supplies its own value.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.
6.4 The heater configuration shall be as indicated in the datasheet.
Heater Configurationselect
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
NOTE 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. (6.5)
6.6 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.
6.7 The burner control mode shall be as indicated in the datasheet.
Burner Control Modeselect
Single stage
Two stage
Modulating
6.8 Combustion technology shall be as indicated in the datasheet.
Combustion Technologyselect
Condensing
Non-condensing
Not applicable to the selected energy source
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 (by default)
NOTE 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. (6.9)
6.10 The redundancy arrangement shall be as indicated in the datasheet.
Redundancy Arrangementselect
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
6.11 Where the datasheet selects a standby arrangement, the control system shall rotate the lead unit on a schedule the Owner can adjust.
6.12 Where the datasheet selects a standby arrangement, the standby unit shall start automatically on failure of a running unit.
NOTE 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. (6.13)

7 Capacity and Storage

NOTE 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. (7.1)
7.2 Storage volume shall be as indicated in the datasheet.
Storage Volumerange
gal
62040508010011917525035050075010001500200030005000
Per drawings — the plumbing equipment schedule (deferred by default)
7.3 Fuel-fired input rating shall be as indicated in the datasheet.
Fuel-Fired Input Ratingrange
Btu/h
300005000075000100000150000199000300000400000500000750000100000015000002000000300000040000006000000
Per drawings — the plumbing equipment schedule (deferred by default)
7.4 Electric input rating shall be as indicated in the datasheet.
Electric Input Ratingrange
kW
136912182436547290120150180240300360480
Per drawings — the plumbing equipment schedule (deferred by default)
7.5 Recovery capacity shall be as indicated in the datasheet.
Recovery Capacityrange
GPH
5153050100200350500750100015002000300045006000
Per drawings — the plumbing equipment schedule (deferred by default)
NOTE 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. (7.6)
7.7 The temperature rise against which recovery capacity is rated shall be as indicated in the datasheet.
Recovery Rating Temperature Riserange
°F
30405060708090100110120140
Derived — the storage temperature setpoint less Site Water Supply Temperature MinimumSite Water Supply Temperature MinimumParameterEach project supplies its own value.site-water-supply-temperature-minimum (by default)
7.8 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.

8 Efficiency and Standby Loss

NOTE 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. (8.1)
8.2 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.
8.3 The metric in which efficiency is expressed and verified shall be as indicated in the datasheet.
Efficiency Rating Metricselect
Uniform energy factor
Thermal efficiency with standby loss
Coefficient of performance at AHRI 1300 rating conditions
Derived — the equipment class of the selected water heater and the federal test procedure that class falls under (by default)
8.4 Minimum thermal efficiency for fuel-fired equipment shall be as indicated in the datasheet.
Minimum Thermal Efficiency — Fuel-Fired Equipmentrange
%
7578808284889092949596979899
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 (by default)
8.5 Minimum uniform energy factor for residential-duty equipment shall be as indicated in the datasheet.
Minimum Uniform Energy Factor — Residential-Duty Equipmentrange
0.54
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 (by default)
8.6 Minimum coefficient of performance for heat pump equipment shall be as indicated in the datasheet.
Minimum Coefficient of Performance — Heat Pump Equipmentrange
1.55
NOTE 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. (8.7)
8.8 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.
8.9 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.

9 Storage Vessel Construction

9.1 Vessel Lining and Wetted Materials

NOTE The lining is the vessel's only corrosion barrier, and every lining trades initial cost against the water chemistry and maintenance regime it tolerates. (9.1.1)
9.1.2 The storage vessel lining shall be as indicated in the datasheet.
Storage Vessel Liningselect
Glass-lined steel
Cement-lined steel
Copper-lined steel
Stainless steel Type 316L
Stainless steel Type 444
NOTE 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. (9.1.3)
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. (9.1.4)
9.1.5 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.
NOTE A cement lining protects the steel by holding a high pH at the steel face, and it depends on staying wet to do so. (9.1.6)
9.1.7 A cement-lined vessel shall not be drained and left empty for longer than the vessel manufacturer permits.
9.1.8 The storage vessel working pressure rating shall be as indicated in the datasheet.
Storage Vessel Working Pressure Ratingrange
psi
100125150160200250300

9.2 Cathodic Protection

NOTE 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. (9.2.1)
9.2.2 Cathodic protection shall be as indicated in the datasheet.
Cathodic Protectionselect
Magnesium sacrificial anode
Aluminum-zinc sacrificial anode
Impressed-current powered anode
None because the vessel material requires no anode
Derived — the storage vessel lining selected and the chemistry of Site Water Supply SourceSite Water Supply SourceParameterEach project supplies its own value.site-water-supply-source (by default)
9.2.3 Every vessel with a lining that depends on cathodic protection shall be furnished with at least one anode accessible from the vessel exterior.
NOTE 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. (9.2.4)
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. (9.2.5)
9.2.6 Where an impressed-current anode is selected, its rectifier shall report loss of output to the monitoring interface specified in this standard.
9.2.7 Anodes shall be located so that one can be withdrawn and replaced without disconnecting any piping connected to the vessel.

9.3 Vessel Insulation

9.3.1 Vessel insulation shall be as indicated in the datasheet.
Storage Vessel Insulationselect
Factory insulation at the federal standby loss minimum
Factory insulation at an enhanced thermal resistance
Factory insulation with a field-applied supplemental jacket
9.3.2 Every storage vessel shall be factory-insulated and jacketed.
9.3.3 Field-applied insulation shall not be accepted in place of factory insulation on any vessel.
9.3.4 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.
NOTE Insulation of the piping connected to the equipment is the subject of Plumbing InsulationPlumbing InsulationResolves to the current adopted revision.sync/plumbing-insulation. (9.3.5)

9.4 Indirect-Fired Vessel Heat Exchanger

NOTE 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. (9.4.1)
9.4.2 Heat exchanger separation shall be as indicated in the datasheet.
Indirect Vessel Heat Exchanger Separationselect
Single-wall heat exchanger
Double-wall vented heat exchanger
Not applicable to the selected heater configuration
Derived — the fluid the heating loop carries and the degree of separation the adopted plumbing code requires between potable water and that fluid (by default)
9.4.3 The heat exchanger coil shall be stainless steel or copper, sized for the design duty at the heating loop supply temperature and flow that Hydronic PipingHydronic PipingResolves to the current adopted revision.sync/hydronic-piping delivers.
9.4.4 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.
9.4.5 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.

10 Combustion Air and Venting

10.1 Combustion Air Supply

NOTE 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. (10.1.1)
10.1.2 The combustion air supply shall be as indicated in the datasheet.
Combustion Air Supplyselect
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
10.1.3 Combustion air openings, ducts, and engineered systems shall be sized in accordance with NFPA 54 or the adopted fuel gas code.
10.1.4 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.
10.1.5 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.

10.2 Vent Category and Material

NOTE 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. (10.2.1)
10.2.2 The vent category shall be as indicated in the datasheet.
Vent Categoryselect
Category I
Category II
Category III
Category IV
Not applicable to the selected energy source
Derived — the draft arrangement of the selected appliance and its combustion technology, classified under ANSI Z21.10.3 and NFPA 54 (by default)
NOTE 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. (10.2.3)
10.2.4 The vent material shall be as indicated in the datasheet.
Vent Materialselect
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
10.2.5 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.
NOTE 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. (10.2.6)
10.2.7 Unless the datasheet selects a plastic vent material, plastic shall not be used to vent a fuel-fired appliance under this standard.
10.2.8 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.
NOTE 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. (10.2.9)

10.3 Vent Arrangement and Termination

10.3.1 The vent arrangement shall be as indicated in the datasheet.
Vent Arrangementselect
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
10.3.2 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.
10.3.3 Appliances from different manufacturers shall not share a positive-pressure vent unless each manufacturer confirms the proposed configuration in writing.
10.3.4 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.
10.3.5 Vent and combustion air terminations shall be located as shown on the roof plan and exterior elevations.
10.3.6 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.

10.4 Condensate from Condensing Equipment

NOTE 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. (10.4.1)
10.4.2 Condensate handling shall be as indicated in the datasheet.
Condensate Handlingselect
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
10.4.3 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.
10.4.4 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.
10.4.5 Condensate piping shall be PVC, CPVC, polypropylene, or stainless steel, and shall not be copper, brass, galvanized steel, or bare carbon steel.
10.4.6 Condensate piping shall be routed to fall continuously to the receptor.
10.4.7 Any condensate pump provided shall alarm on high level to the monitoring interface specified in this standard.
10.4.8 Condensate discharge shall terminate over the receptors shown on the plumbing plans.

11 Fuel Gas Connection at the Equipment

NOTE Fuel gas piping upstream of the equipment connection is the subject of Fuel Gas PipingFacility Liquefied-Petroleum and Fuel Gas PipingResolves to the current adopted revision.sync/fuel-gas-piping; this article covers only the train between that piping and the appliance. (11.1)
11.2 Each fuel-fired appliance shall be provided with a manual shutoff valve outside the appliance jacket and within sight of the appliance it serves.
11.3 Each fuel-fired appliance shall be provided with a sediment trap downstream of the manual shutoff valve and upstream of the appliance inlet.
11.4 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.
11.5 Each fuel-fired appliance shall be provided with a pressure test port at the appliance inlet for combustion setup.
11.6 An at-heater gas pressure regulator shall be provided as indicated in the datasheet.
At-Heater Gas Pressure Regulatorselect
Required
Not required
Not applicable to the selected energy source
Derived — the gas distribution pressure delivered to the appliance compared against the maximum inlet pressure the appliance is listed for (by default)
11.7 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.
11.8 Where the appliance is fired on fuel oil, the oil supply, tank, and burner installation shall comply with NFPA 31.

12 Heat Pump Water Heating Equipment

NOTE 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. (12.1)
12.2 The heat pump source shall be as indicated in the datasheet.
Heat Pump Sourceselect
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
12.3 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.
12.4 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.
12.5 Condensate produced by dehumidification of the source air shall be piped to a receptor, trapped as the unit manufacturer requires, and pitched to drain.
12.6 The refrigerant safety class shall be as indicated in the datasheet.
Heat Pump Refrigerant Safety Classselect
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
12.7 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.
12.8 Where the equipment uses a flammable refrigerant, the Contractor shall install the leak detection, ventilation, and mitigation provisions the equipment listing requires.
12.9 Leak detection alarm outputs shall be reported to the monitoring interface specified in this standard.
NOTE 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. (12.10)
12.11 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.
12.12 The supplemental heat source shall be as indicated in the datasheet.
Supplemental Heat Sourceselect
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
12.13 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.
12.14 Maximum sound level shall be as indicated in the datasheet.
Heat Pump Maximum Sound Level at 3 ftrange
dBA
3580
NOTE 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. (12.15)

13 Electrical Connection at the Equipment

NOTE Electrical work upstream of the disconnecting means is the subject of the electrical standards; this article covers the connection requirements the equipment itself imposes. (13.1)
13.2 Supply voltage shall be as indicated in the datasheet.
Supply Voltagerange
V
120208240277347480600
Per drawings — the plumbing equipment schedule (deferred by default)
13.3 Supply phase shall be as indicated in the datasheet.
Supply Phaseselect
1Φ
3Φ
Per drawings — the plumbing equipment schedule (deferred by default)
13.4 The disconnecting means shall be as indicated in the datasheet.
Disconnecting Meansselect
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
13.5 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.
13.6 Branch-circuit conductors, overcurrent protection, and the disconnecting means rating shall match the nameplate values of the equipment actually furnished.
13.7 The Contractor shall report any difference between those nameplate values and the scheduled electrical characteristics before rough-in.
13.8 Equipment grounding and bonding shall comply with Grounding And BondingGrounding and Bonding for Electrical SystemsResolves to the current adopted revision.sync/grounding-and-bonding.
13.9 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.

14 Temperature Setpoints and Legionella Control

14.1 Storage and Delivery Temperatures

NOTE 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. (14.1.1)
14.1.2 The storage temperature setpoint shall be as indicated in the datasheet.
Storage Temperature Setpointrange
°F
120125130135140145150160170180
14.1.3 The delivered distribution temperature setpoint shall be as indicated in the datasheet.
Delivered Distribution Temperature Setpointrange
°F
105110115120124130135140
14.1.4 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.
14.1.5 The Contractor shall install the equipment that the specified compensating control requires.
14.1.6 The minimum recirculation return temperature shall be as indicated in the datasheet.
Minimum Recirculation Return Temperaturerange
°F
100105110115120124130135
Derived — the delivered distribution temperature setpoint less the loop temperature drop the water management program permits (by default)
NOTE 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. (14.1.7)
14.1.8 The thermal disinfection capability shall be as indicated in the datasheet.
Thermal Disinfection Capabilityselect
None
A manual elevated-temperature flush procedure documented in the operating manual
An automatic scheduled elevated-temperature cycle through the mixing station
14.1.9 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.

14.2 Master Mixing Valve

NOTE 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. (14.2.1)
14.2.2 The master mixing valve type shall be as indicated in the datasheet.
Master Mixing Valve Typeselect
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
14.2.3 The master mixing valve arrangement shall be as indicated in the datasheet.
Master Mixing Valve Arrangementselect
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
14.2.4 The master mixing valve body material shall be as indicated in the datasheet.
Master Mixing Valve Body Materialselect
Bronze
Dezincification-resistant brass
Stainless steel
14.2.5 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.
NOTE 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. (14.2.6)
14.2.7 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.
14.2.8 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.
14.2.9 The master mixing valve shall be furnished with a means of locking or sealing the setpoint after commissioning.

14.3 Downstream Temperature Limiting

14.3.1 The scope of downstream temperature limiting shall be as indicated in the datasheet.
Downstream Temperature Limiting Scopeselect
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
Derived — the delivered distribution temperature setpoint compared against the fixture delivery temperature limits the adopted plumbing code imposes on the fixtures served (by default)
14.3.2 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.
14.3.3 Showers and tub-shower combinations shall be served by a compensating valve listed to ASSE 1016 in addition to any upstream limiting device.
14.3.4 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.
NOTE Selection and installation of the fixture-mounted devices themselves is the subject of Plumbing FixturesPlumbing FixturesResolves to the current adopted revision.sync/plumbing-fixtures. (14.3.5)

15 Thermal Expansion Control

NOTE 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. (15.1)
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. (15.2)
15.3 Thermal expansion control shall be as indicated in the datasheet.
Thermal Expansion Controlselect
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
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 (by default)
NOTE Whether the building water service contains a check valve, a backflow assembly, or a pressure reducing valve is determined by Backflow PreventionBackflow PreventionResolves to the current adopted revision.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. (15.4)
15.5 The expansion vessel bladder material shall be as indicated in the datasheet.
Expansion Vessel Bladder Materialselect
Butyl
Polypropylene-lined butyl
Stainless steel bellows
15.6 The expansion vessel acceptance volume shall be as indicated in the datasheet.
Expansion Vessel Acceptance Volumerange
gal
0.5124.48.5142032446280120200
Derived — the system water volume, the rise from Site Water Supply Temperature MinimumSite Water Supply Temperature MinimumParameterEach project supplies its own value.site-water-supply-temperature-minimum to the storage temperature setpoint, and the system static and relief pressures (by default)
15.7 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.
15.8 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.
15.9 The Contractor shall record the measured static pressure and the pre-charge as set in the startup report.
NOTE 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. (15.10)

16 Temperature and Pressure Relief

16.1 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.
16.2 The relief valve set pressure shall be as indicated in the datasheet.
Relief Valve Set Pressurerange
psi
75100125150160200250300
Derived — the working pressure rating of the storage vessel the valve protects (by default)
16.3 The relief valve set temperature shall be 210°F.
16.4 The relief valve relieving capacity in Btu/h shall equal or exceed the input rating of the equipment it protects.
16.5 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.
16.6 No valve, restriction, or reduction in size shall be installed between the vessel and the relief valve inlet.
16.7 The relief discharge piping material shall be as indicated in the datasheet.
Relief Discharge Piping Materialselect
Copper Type L
CPVC
Galvanized steel
Stainless steel
16.8 Relief discharge piping shall be the full size of the relief valve outlet over its entire length.
16.9 Relief discharge piping shall be rated for 210°F.
16.10 Relief discharge piping shall fall continuously from the valve to its point of termination.
16.11 Relief discharge piping shall terminate through an air gap over a receptor placed where a discharge is visible to operating staff.
16.12 Relief discharge piping shall not be trapped, valved, or threaded at its outlet end.
16.13 Relief discharge tubes and their fittings shall comply with ASME A112.4.1.

17 Hot Water Delivery and Recirculation

17.1 Delivery Method

NOTE 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. (17.1.1)
17.1.2 The hot water delivery method shall be as indicated in the datasheet.
Hot Water Delivery Methodselect
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
NOTE Where heat tracing is selected, the cable, controls, and installation are the subject of Electric Heat TracingElectric Heat TracingResolves to the current adopted revision.sync/electric-heat-tracing. (17.1.3)
17.1.4 The recirculation return connection point shall be as indicated in the datasheet.
Recirculation Return Connection Pointselect
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
NOTE 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. (17.1.5)
17.1.6 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.
NOTE The recirculation loop and its return main are the subject of Domestic Water PipingDomestic Water PipingResolves to the current adopted revision.sync/domestic-water-piping; this article governs the pump, its control, and the devices that balance the loop. (17.1.7)

17.2 Recirculation Pump

17.2.1 The recirculation design flow rate shall be as indicated in the datasheet.
Recirculation Design Flow Raterange
GPM
0.5123581220305075100150200
Per drawings — the plumbing equipment schedule (deferred by default)
17.2.2 The recirculation pump motor type shall be as indicated in the datasheet.
Recirculation Pump Motor Typeselect
A wet-rotor permanent-magnet electronically commutated motor
A wet-rotor fixed-speed induction motor
A close-coupled inline pump with a separate motor
17.2.3 The recirculation pump wetted material shall be as indicated in the datasheet.
Recirculation Pump Wetted Materialselect
Bronze
Stainless steel
Engineered polymer
17.2.4 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.
17.2.5 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.
17.2.6 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.
17.2.7 Motors furnished under this standard shall comply with Electric MotorsCommon Motor Requirements for Electrical EquipmentResolves to the current adopted revision.sync/electric-motors.

17.3 Recirculation Control

NOTE 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. (17.3.1)
17.3.2 The recirculation pump control shall be as indicated in the datasheet.
Recirculation Pump Controlselect
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
17.3.3 Except where the datasheet selects continuous operation, the recirculation pump control shall stop the pump when the loop is at temperature.
17.3.4 Except where the datasheet selects continuous operation, the recirculation pump control shall stop the pump outside the building's occupied schedule.
17.3.5 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.
NOTE 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. (17.3.6)
17.3.7 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.
17.3.8 The Contractor shall record that schedule configuration in the closeout submittals.

17.4 Recirculation Balancing

NOTE 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. (17.4.1)
17.4.2 The recirculation balancing method shall be as indicated in the datasheet.
Recirculation Balancing Methodselect
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
17.4.3 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.
17.4.4 The Contractor shall coordinate the balancing device locations with the riser and branch arrangement shown on the plumbing riser diagrams.
17.4.5 The Contractor shall balance the recirculation system after the loop has reached its operating temperature.
17.4.6 The Contractor shall record the flow or the return temperature achieved at each balancing device.
17.4.7 The Contractor shall set and lock the memory stop on each balancing device that has one.
17.4.8 Balancing valves shall be installed with a means of measuring the temperature of the branch return immediately upstream of each device.

18 Equipment Controls and Monitoring

18.1 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.
18.2 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.
18.3 The factory-furnished control package shall not be modified, bypassed, or defeated.
18.4 Any field-furnished control shall be external to the appliance and shall not override a safety function.
18.5 The equipment monitoring interface shall be as indicated in the datasheet.
Equipment Monitoring Interfaceselect
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
18.6 The points reported to the monitoring interface shall be as indicated in the datasheet.
Monitored Pointscheckbox
☐ 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
NOTE 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. (18.7)
18.8 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.
18.9 Each monitored temperature sensor shall be verified at startup against a traceable reference and shall read within ±2°F of it.
18.10 Network points, addressing, and the communication protocol shall be coordinated with Building Automation SystemBuilding Automation SystemResolves to the current adopted revision.sync/building-automation-system.

19 Installation

19.1 Equipment Setting and Anchorage

19.1.1 The equipment support shall be as indicated in the datasheet.
Equipment Supportselect
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
19.1.2 Equipment shall be set level, fully bearing on its support, and shimmed only with corrosion-resistant shims where leveling is required.
19.1.3 The seismic anchorage shall be as indicated in the datasheet.
Seismic Anchorageselect
None required
Strap anchorage to adjacent structure
A pre-approved anchorage detail listed by an evaluation agency
Project-specific anchorage engineered for the installation
Derived — Seismic Design CategorySeismic Design CategoryParameterEach project supplies its own value.seismic-design-category and the component importance factor the project assigns to domestic hot water service (by default)
19.1.4 Anchorage shall resist the seismic forces ASCE 7 assigns to the component.
19.1.5 Where anchorage is engineered for the project, the anchorage design shall be sealed by a registered design professional licensed in the project's jurisdiction.
19.1.6 Where a pre-approved anchorage detail is used, it shall be a detail listed for the equipment weight, geometry, and mounting condition actually installed.
19.1.7 Anchorage details, isolation, and restraint hardware shall comply with Vibration Isolation And Seismic RestraintVibration Isolation and Seismic RestraintResolves to the current adopted revision.sync/vibration-isolation-and-seismic-restraint.
19.1.8 Anchorage shall not bear on the vessel jacket or insulation in a way that crushes it.
19.1.9 Any spacer required to prevent that bearing shall be furnished by the vessel manufacturer or cut from a material the vessel manufacturer accepts.

19.2 Water Piping Connections at the Equipment

19.2.1 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.
19.2.2 Each equipment water connection shall be provided with an isolation valve.
19.2.3 A dielectric fitting shall be installed wherever a copper or bronze equipment connection meets ferrous building piping.
19.2.4 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.
19.2.5 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.
19.2.6 Piping shall be supported independently of the equipment so that no piping weight or thermal movement is carried by an equipment connection.

19.3 Gauges, Thermometers, and Identification

19.3.1 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.
19.3.2 A thermometer shall be provided on the mixing valve outlet and on the recirculation return immediately upstream of its connection to the equipment.
19.3.3 Gauges and thermometers shall be positioned so they can be read from the front of the equipment without removing a cover or a shield.
19.3.4 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.
19.3.5 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.
19.3.6 Pipe and valve identification shall comply with Plumbing Piping IdentificationPlumbing Piping IdentificationResolves to the current adopted revision.sync/plumbing-piping-identification.

20 Startup and Field Testing

20.1 Pre-Startup Verification

20.1.1 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.
20.1.2 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.
20.1.3 The Contractor shall verify before startup that the expansion vessel pre-charge has been set against the measured static pressure.
20.1.4 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.
20.1.5 The Contractor shall verify before startup that the vent system is complete, unobstructed, correctly supported, and terminated as specified.
20.1.6 The Contractor shall verify before startup that the condensate drain is open and routed to its receptor and that any neutralizer contains fresh media.
20.1.7 The Contractor shall verify before startup that the electrical supply matches the equipment nameplate and that the disconnecting means is installed and accessible.

20.2 Startup

20.2.1 Startup shall be performed by a technician qualified under this standard for the equipment class being started.
20.2.2 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.
20.2.3 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.
20.2.4 Startup shall include verification of the high-temperature limit by a simulated overtemperature condition.
20.2.5 Startup shall include verification of the relief valve by operation of its test lever, followed by confirmation that the valve reseats without leakage.
20.2.6 Startup shall include verification of recirculation pump rotation, flow, and control response.
20.2.7 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.

20.3 Field Performance Test

20.3.1 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.
20.3.2 The field performance test shall verify the items indicated in the datasheet.
Field Performance Test Documentationcheckbox
☐ 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
20.3.3 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.
20.3.4 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.
20.3.5 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.
20.3.6 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.
20.3.7 The field performance test shall verify that combustion results fall within the range the appliance manufacturer publishes.
20.3.8 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.
20.3.9 Where a test result falls outside a specified tolerance, the Contractor shall correct the cause and retest at no cost to the Owner.
20.3.10 Where the parties disagree whether an observed condition constitutes a failed result, the Engineer of Record shall make the initial determination.
NOTE Commissioning activities beyond this test are the subject of CommissioningTotal Building CommissioningResolves to the current adopted revision.sync/commissioning. (20.3.11)

20.4 Disinfection Before Use

20.4.1 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 Disinfection Of Water SystemsDisinfection of Domestic Water SystemsResolves to the current adopted revision.sync/disinfection-of-water-systems.
20.4.2 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.

21 Delivery, Storage, and Handling

21.1 Equipment shall be delivered in the manufacturer's packaging with factory covers, plugs, and tags in place.
21.2 The Contractor shall inspect equipment for shipping damage on arrival at the site.
21.3 The Contractor shall report shipping damage in writing to the carrier and to the equipment manufacturer before the damaged item is installed.
21.4 Damaged equipment shall not be installed until the manufacturer confirms in writing that the damage does not affect its performance, listing, or warranty.
21.5 Equipment shall be stored indoors on level dunnage, above freezing, and protected from weather, construction water, and physical damage until it is installed.
21.6 Insulated vessels and packaged heaters shall not be stacked.
21.7 Equipment containing refrigerant shall be stored and transported in the orientation the manufacturer permits.
NOTE 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. (21.8)
21.9 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.
21.10 The Contractor shall record the settling period observed before the unit was energized.
21.11 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.
21.12 Open pipe and vent ends shall be capped until the connection is made.

22 Warranty

22.1 The Contractor shall procure equipment carrying at least the warranty coverage indicated in the datasheet.
22.2 The Contractor shall furnish evidence of that coverage in the closeout submittals.
Warranty Period — Storage Vessel or Heat Exchangerrange
yr
1356810121520
Warranty Period — Parts and Laborrange
yr
1235710
22.3 Where the datasheet indicates no warranty period, the equipment shall carry the standard published warranty for its class.
22.4 Where the equipment carries the standard published warranty, the Contractor shall state that period in the closeout submittals.
22.5 The warranty period shall begin at substantial completion or at the date of beneficial use by the Owner, whichever is earlier.
22.6 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.
22.7 The Contractor shall bear the cost of removing and reinstalling adjacent work required to reach a component being repaired under warranty.
22.8 The Contractor shall record the condition of that adjacent work before it is disturbed and shall restore it to the recorded condition.
22.9 Warranty coverage shall not be voided by water chemistry within the limits the equipment manufacturer publishes.
22.10 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.

23 Spare Parts

23.1 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
Spare Parts Deliverycheckbox
☐ 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
23.2 The Contractor shall obtain the Owner's signed receipt for the spare parts delivered.

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