+---
+title: HVAC Water Treatment
+category: Mechanical
+toc_depth: 3
+description: >
+ When to use: Chemical and physical water treatment for HVAC water systems in commercial, institutional, and industrial buildings. Covers closed hydronic loops (heating hot water, chilled water, dual-temperature, water-source heat pump, ground source loop), open recirculating condenser-water systems serving cooling towers and evaporative condensers, glycol-protected closed loops at any concentration, and low-pressure steam and condensate-return systems up to 150 psig. Scope includes pre-operational cleaning and flushing, alkaline degreasing and acid passivation where required, initial inhibitor charge, ongoing inhibitor and biocide dosing, side-stream filtration, automatic chemical feed and bleed control, conductivity- and corrosion-coupon-based monitoring, sample-port provisions, service contract requirements, and the documentation package needed to support a building water management plan under ASHRAE Standard 188.
+
+ Not intended for: Domestic potable hot and cold water (see [[sync/domestic-water-piping]]); pure-water and reverse-osmosis loops serving humidifiers, laboratory equipment, or process; high-pressure steam systems above 150 psig (governed by ASME B31.1 and a process-grade boiler water program); fire protection sprinkler piping (see [[sync/wet-pipe-fire-sprinkler-systems]]); refrigerant circuits (governed by refrigerant equipment standards); fuel oil; or municipal water mains upstream of the building water service. The pumps, piping, expansion devices, and air separators that this treatment program protects are covered in companion standards [[sync/hydronic-piping]] and [[sync/hvac-pumps]]; air-handler cooling coils that share the same chilled water are covered in [[sync/air-handling-units]]; chemical-feed pumps, conductivity controllers, and metering devices that integrate with the building automation system are coordinated through [[sync/building-automation-system]].
+---
+
+# Scope
+
+This standard covers the design, equipment, materials, and ongoing program for chemical and physical treatment of water and water-glycol fluids in HVAC service. The systems addressed are closed hydronic loops (heating hot water, chilled water, dual-temperature, water-source heat pump and ground-source heat pump loops, and any closed loop protected with propylene or ethylene glycol), open recirculating condenser-water systems serving open- and closed-circuit cooling towers and evaporative condensers, and low-pressure steam and condensate-return systems serving humidifiers, sterilizers, and heating boilers. The work includes initial inspection and analysis of make-up water and any existing system water; the pre-operational cleaning and flushing of new piping, vessels, and equipment; pre-passivation of clean metal surfaces before the system is placed in service; the initial chemical charge that establishes baseline corrosion-inhibitor, scale-inhibitor, and biocide levels; the equipment that doses, monitors, bleeds, and filters the circulating fluid; and the service program that maintains chemistry within control ranges throughout the system's life. The standard also defines the documentation that the design team and the Owner need to satisfy ASHRAE Standard 188's requirements for a building water management program where open recirculating systems are present.
+
+Water treatment is the single most important determinant of long-term hydronic system reliability. A closed loop with disciplined inhibitor maintenance can run for thirty years with the original pipe and pump internals intact; a closed loop run on raw fill water with no inhibitor program will lose its first heat exchanger to oxygen pitting within two years and accumulate iron-oxide sludge that disables the coldest, slowest-velocity branches first. An open condenser water system without effective scale, corrosion, and biological control will scale a cooling tower fill in a single hot-weather season, accelerate condenser-tube failures, and — in the case of biological control failure — present a documented Legionellosis transmission risk that has produced both fatalities and litigation. The treatment program described here is not a discretionary refinement; it is the operational layer that determines whether the hydronic and refrigeration equipment specified elsewhere in these documents will reach the end of its design life.
+
+The boundary of work under this standard begins at the make-up water connection to each treated system, continues through all chemical feed, monitoring, bleed-off, and filtration equipment, and includes the chemical reservoirs, day-tanks, and chemical-storage room provisions located in the central plant. The interconnecting piping that carries treated water through the building — the hydronic distribution mains, branch piping, expansion devices, and air separators that the program protects — is covered in [[sync/hydronic-piping]]; pumps that circulate the treated fluid are covered in [[sync/hvac-pumps]]; cooling coils and heat exchangers exposed to the treated fluid are covered in the respective equipment standards including [[sync/air-handling-units]]; and the conductivity controllers, chemical-feed pumps, and metering devices that report to the BAS are coordinated through [[sync/building-automation-system]]. Where open recirculating systems are present, the building's overall water management plan, prepared in accordance with ASHRAE Standard 188 and the local public health authority's requirements, integrates this standard's monitoring data, control set points, and corrective-action procedures into a single facility document maintained by the Owner.
+
+# Referenced Standards
+
+Equipment, materials, treatment programs, and installation shall comply with the latest adopted edition of the following standards and guidelines unless a specific edition is cited. Where the contract documents, the adopted building or mechanical code, the local public health authority's water-management requirements, or a referenced standard impose conflicting requirements, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
+
+| Standard | Title |
+|----------|-------|
+| ANSI/ASHRAE 188 | Legionellosis: Risk Management for Building Water Systems |
+| ASHRAE Guideline 12 | Managing the Risk of Legionellosis Associated with Building Water Systems |
+| ASHRAE Handbook — HVAC Applications | Chapter on Water Treatment: Deposition, Corrosion, and Biological Control |
+| ASHRAE Handbook — HVAC Systems and Equipment | Chapters on Hydronic Heating and Cooling and on Cooling Towers |
+| ANSI/ASHRAE/IES 90.1 | Energy Standard for Buildings Except Low-Rise Residential Buildings |
+| CTI STD-159 | Acceptable Water for Cooling Tower Make-Up |
+| CTI WTP-148 | Legionellosis Guideline: Best Practices for Control of Legionella |
+| AWT Technical Reference and Training Manual | Association of Water Technologies — recommended practice for industrial water treatment programs |
+| ASTM D1141 | Standard Practice for the Preparation of Substitute Ocean Water (reference for chloride aggressiveness comparisons) |
+| ASTM D1193 | Standard Specification for Reagent Water (laboratory test water purity grades) |
+| ASTM D596 | Standard Guide for Reporting Results of Analysis of Water |
+| ASTM D2688 | Standard Test Methods for Corrosivity of Water in the Absence of Heat Transfer (Weight Loss Methods) — corrosion coupon practice |
+| ASTM D3370 | Standard Practices for Sampling Water from Closed Conduits |
+| ASTM D4012 | Standard Test Method for Adenosine Triphosphate (ATP) Content of Microorganisms in Water — rapid microbiological screening |
+| AWWA C651 | Disinfecting Water Mains (reference for chlorination procedure) |
+| AWWA B100 | Granular Filter Material |
+| NACE SP0189 (now AMPP) | On-Line Monitoring of Cooling Waters |
+| NACE SP0775 (now AMPP) | Preparation, Installation, Analysis, and Interpretation of Corrosion Coupons in Oilfield Operations (adapted to HVAC) |
+| ASME B31.9 | Building Services Piping |
+| NSF/ANSI 60 | Drinking Water Treatment Chemicals — Health Effects (where treated water may contact potable systems) |
+| NSF/ANSI 50 | Equipment and Chemicals for Swimming Pools, Spas, Hot Tubs, and Other Recreational Water Facilities (reference for biocide handling) |
+| FDA 21 CFR 173.310 | Boiler Water Additives (where steam contacts food) |
+| EPA FIFRA | Federal Insecticide, Fungicide, and Rodenticide Act — registration of biocidal products |
+| OSHA 29 CFR 1910.1200 | Hazard Communication Standard (chemical container labeling, SDS) |
+| OSHA 29 CFR 1910.119 | Process Safety Management (where bulk chemical thresholds are exceeded) |
+| DOT 49 CFR | Hazardous Materials Regulations (chemical shipment) |
+| IBC | International Building Code (chemical storage room rating and ventilation) |
+| IFC | International Fire Code (hazardous materials storage and signage) |
+| IPC / UPC | International Plumbing Code or Uniform Plumbing Code as adopted (cross-connection control, make-up backflow prevention) |
+| ASSE 1013 | Performance Requirements for Reduced Pressure Principle Backflow Prevention Assemblies |
+
+The Owner's local public health authority — typically a state department of health or a state department of environmental services — may publish additional requirements for cooling tower registration, Legionella sampling, and water management plan content. These requirements take precedence within their jurisdiction and shall be incorporated into the program by the design team and the water treatment service provider.
+
+# Submittals
+
+## Action Submittals
+
+The Contractor and the water treatment service provider shall submit the following for the Engineer's review and return before procurement, before the initial chemical charge, and before any acid or alkaline cleaning operation begins. Cleaning and chemical addition shall not start on any system until the corresponding submittals are reviewed and returned, because the consequences of using the wrong chemistry or the wrong sequence are typically irreversible — passivation cannot be undone, and chemistry compatibility errors can scrap a coil run or strip a galvanized cooling tower of its protective coating.
+
+- A pre-design water analysis for the project's intended make-up water source, including total hardness as CaCO3, calcium hardness, total alkalinity, chloride, sulfate, silica, total dissolved solids (TDS) or conductivity, pH, iron, manganese, and total organic carbon. The analysis shall be performed by an independent laboratory using current ASTM methods and shall be no more than twelve months old. Where the building draws from a well, an analysis from each well shall be submitted; where the building draws from a municipal supply, the most recent annual Consumer Confidence Report from the supplier shall accompany the laboratory analysis.
+- A written treatment design for each system — closed HHW, closed CHW, condenser-water, glycol loop, steam — identifying the proposed inhibitor chemistry, scale inhibitor where applicable, biocide types and rotation, expected control ranges for each parameter, target cycles of concentration for open systems, and the conductivity, oxidation-reduction potential (ORP), or other set point on which automatic feed and bleed are based.
+- Product data sheets and Safety Data Sheets (SDS) for every chemical product proposed for use on the project, including initial cleaner, passivator, inhibitor, biocide, and any specialty products. The SDS shall be the current version published within the last three years.
+- EPA registration documentation for every biocidal product, demonstrating the product is registered under FIFRA for the use proposed. Non-registered or off-label use of biocides shall not be permitted.
+- Compatibility statement confirming that each treatment chemical is compatible with the materials of construction in each system — copper, copper alloys, carbon steel, stainless steel, galvanized steel where present, cast iron, aluminum where present, EPDM, NBR, and the gasket materials used in grooved couplings, flanges, and pump seals. Where galvanized steel cooling towers are present, the compatibility statement shall specifically address white-rust prevention chemistry. Where aluminum components are present (some pump impellers, some heat exchangers, some humidifier cylinders), the compatibility statement shall confirm that the proposed chemistry maintains pH and inhibitor levels within the narrow window aluminum tolerates.
+- Pre-operational cleaning plan for each system, including the sequence of fill, circulation, drain, flush, and refill operations; the cleaner concentration, temperature, and circulation time; the velocity that will be maintained during flushing; the temporary piping, bypasses, and strainers required to protect coils and small-bore equipment; and the acceptance criteria for flush completion.
+- Pre-passivation plan for each closed system, identifying the passivator chemistry, dosage, circulation time, and temperature, and the corrosion-coupon installation that will document the passivation result.
+- Chemical feed and control equipment shop drawings, showing each chemical feed pump, day-tank or bulk tank, feed line routing, isolation valves, calibration columns, conductivity probe location, ORP probe location (open systems), flow switch location, bleed-off solenoid and metering equipment, side-stream filter, and sample-port locations. Locations shall be coordinated with chemical-storage room layout, structural housekeeping pads, BAS conduit, and clearance to permit chemical drum changeout without disassembly.
+- Side-stream filter product data including filtration micron rating, design flow, design pressure drop clean and dirty, backwash or change-out interval and method, and connection details.
+- Sample-port locations and details for each system, showing port type, isolation valve, drain, and the sequence in which the port will be used during sampling.
+- Cooling tower drift-eliminator data confirming maximum drift loss of 0.005% of recirculating flow or less for any open tower as required by ASHRAE 188 risk management.
+- A draft Water Management Plan template (open systems only) prepared in accordance with ASHRAE Standard 188 and the local public health authority's requirements, identifying the building water systems within scope, the control measures for each system, the control limits, the monitoring schedule, and the documentation and corrective-action procedures. Final plan content depends on Owner inputs and shall be completed before substantial completion.
+- Service contract proposal identifying the scope of routine service, the frequency of visits, the parameters tested at each visit, the third-party laboratory used for any off-site analysis, the corrosion-coupon installation and reading schedule, the cooling tower Legionella sampling schedule (where applicable), the after-hours response commitment, and the chemical-supply replenishment basis.
+
+```datasheet
+label: Action Submittals Required
+type: checkbox
+options:
+ - "Pre-design make-up water analysis (independent laboratory)"
+ - "Treatment design narrative per system"
+ - "Chemical product data and Safety Data Sheets"
+ - "EPA FIFRA registration for each biocidal product"
+ - "Materials compatibility statement"
+ - "Pre-operational cleaning plan per system"
+ - "Pre-passivation plan per closed system"
+ - "Chemical feed and control equipment shop drawings"
+ - "Side-stream filter product data"
+ - "Sample-port locations and details"
+ - "Drift-eliminator data (open systems)"
+ - "Draft ASHRAE 188 Water Management Plan template"
+ - "Service contract proposal"
+default: "Pre-design make-up water analysis (independent laboratory)"
+```
+
+## Closeout Submittals
+
+At substantial completion, before each treated system is accepted by the Owner, the following shall be delivered. The closeout package is the document trail that allows the Owner's service provider to take over the program, that the Owner's facility staff need to operate the system, and that the Owner needs to demonstrate compliance with ASHRAE 188 and any state cooling tower registration requirement.
+
+- Signed and dated cleaning and flushing reports for each system, documenting cleaner used and concentration, circulation time and temperature, the flushed water clarity at acceptance, the iron and total suspended solids measured in the final flush, and the sign-off of both the installing contractor and the water treatment service provider.
+- Signed and dated pre-passivation reports for each closed system, with the inhibitor concentration achieved, the circulation time and temperature, and any corrosion-coupon weight-loss result available at the time of acceptance.
+- Initial water analysis reports for each system showing the system filled with treated water and within all control ranges before the system was placed into operating service.
+- Operation and maintenance manuals for all treatment equipment — chemical feed pumps, conductivity and ORP controllers, side-stream filters, sample ports, bleed-off equipment — including manufacturer's parts lists, replacement schedules, and calibration procedures.
+- BAS point list and control narratives for all chemical-feed-related signals (conductivity, ORP, make-up flow, bleed-off flow, chemical-day-tank level alarms, side-stream filter differential pressure) integrated with [[sync/building-automation-system]].
+- A printed Water Management Plan binder (open systems) that includes the system descriptions, control measures, control limits, monitoring procedures, corrective-action procedures, communication and documentation procedures, the names and contact information of the water management team, and signature pages for the building owner, the operating engineer, and the water treatment service provider.
+- A Chemical Inventory List with the SDS for each chemical present on site, the location of each chemical, the maximum quantity stored, and the spill-response procedure.
+- The first six months of the service contract, with a documented service-visit schedule and a defined point of contact, included in the base bid.
+
+# Quality Assurance
+
+## Service Provider Qualifications
+
+The water treatment service provider — the entity that supplies chemistry, performs cleaning and passivation, and provides ongoing service — shall be a firm whose primary business is industrial water treatment, with a minimum of five years of continuous experience treating commercial HVAC water systems of comparable size and complexity. The provider shall employ certified water technologists; certification by the Association of Water Technologies (AWT Certified Water Technologist, CWT) or equivalent third-party credential shall be held by at least one technician assigned to the project. The provider shall maintain product liability and professional liability insurance appropriate to the scope of work, and shall maintain an EPA establishment number where any treatment product is repackaged or blended at the provider's facility.
+
+## Manufacturer-Independent Selection
+
+The water treatment service provider's chemistry recommendations shall be technically justified — proposed inhibitors and biocides shall be selected because they suit the project's make-up water, materials of construction, and operating regime, not because they are part of a vendor's exclusive product line. Where a project has multiple bidders, each bidder shall propose chemistry meeting the same performance criteria, evaluated on cost-per-treatment-cycle and program completeness rather than on brand. The Owner is free to change service providers without re-cleaning the system; the program description shall be specific enough that a successor provider can match chemistry parameters.
+
+## Materials Compatibility Verification
+
+Before initial chemical charge, the service provider shall verify in writing that the proposed chemistry is compatible with every material in the wetted path: pipe metallurgy at every section (carbon steel, copper, stainless steel, galvanized where present), pump and valve bodies, mechanical seal faces and elastomers, gasket compounds at flanges and grooved couplings, heat exchanger tube and shell materials, expansion-tank diaphragm material, and any aluminum component such as aluminum cylinders in steam humidifiers or aluminum impellers in light-duty pumps. The verification shall identify any incompatibility, propose a substitute chemistry or a control measure (such as pH window narrowing), and shall be signed by the service provider's technical authority before chemistry is added.
+
+```datasheet
+label: Materials Compatibility Verification — Signed by Service Provider
+type: radio
+options:
+ - "Required and on file before initial chemical charge"
+ - "Required at every chemistry change, not only initial fill"
+ - "Both — initial and on every product substitution"
+default: "Both — initial and on every product substitution"
+```
+
+## Cross-Connection Control
+
+Make-up water connections to all treated systems shall be protected by backflow prevention assemblies of the type and rating required by the adopted plumbing code and the local cross-connection control authority. Treated water shall not be permitted to flow back into the domestic supply at any operating condition. For chemically treated systems, the minimum backflow protection device is typically a reduced-pressure principle backflow prevention assembly (RPBA) conforming to ASSE 1013; many jurisdictions specifically require RPBA on open cooling tower make-up because the chemistry contains biocides registered under FIFRA. The Contractor shall confirm the specific device type with the local cross-connection control authority before procurement and shall install the assembly in a location accessible for the annual test required by the cross-connection program.
+
+```datasheet
+label: Make-up Water Backflow Prevention
+type: radio
+options:
+ - "Reduced Pressure Principle Assembly (RPBA), ASSE 1013 — standard for all chemically treated systems"
+ - "Air Gap (AG) — where physical separation is feasible and acceptable to AHJ"
+ - "Double Check Backflow Assembly (DCBA), ASSE 1015 — closed loops only, where AHJ accepts"
+default: "Reduced Pressure Principle Assembly (RPBA), ASSE 1013 — standard for all chemically treated systems"
+```
+
+## Chemical Storage Room
+
+A dedicated chemical storage room or area shall be provided for the treatment program's bulk chemistry, with the following minimum provisions: a chemical-resistant floor coating; secondary containment sized for at least 110% of the largest tank in the room; a floor drain that does not directly connect to a storm sewer or sanitary sewer without spill-isolation provisions; eyewash and emergency shower meeting ANSI Z358.1; mechanical ventilation that meets the IBC and IFC requirements for the chemical hazard class present; chemical-compatible separation between incompatible products (acids separated from oxidizers, oxidizers separated from organic biocides); spill response materials (absorbent, containment booms); and posted Safety Data Sheets in a weatherproof binder at the room entry. Where bulk chemistry quantities exceed the IFC thresholds for hazardous occupancy classification, the room shall be classified and constructed accordingly.
+
+```datasheet
+label: Chemical Storage Room — Secondary Containment Capacity
+type: radio
+options:
+ - "110% of largest single tank (code minimum)"
+ - "150% of largest single tank (recommended where multiple bulk tanks present)"
+ - "Sum of all stored chemical volumes (worst-case complete-failure containment)"
+default: "110% of largest single tank (code minimum)"
+```
+
+# Water Analysis — Pre-Design
+
+## Significance of Make-Up Water Quality
+
+Every treatment program is built on the chemistry of the make-up water available at the project site, because make-up water continuously refreshes the system either through evaporation (open systems) or through small steady losses to leakage, drain-down, and routine venting (closed systems). The hardness, alkalinity, chloride, silica, and conductivity of the make-up water determine the cycles of concentration achievable in an open tower, the scaling potential at evaporator surfaces, the corrosion aggressiveness of the resulting concentrated water, and the inhibitor consumption rate. A program designed for soft, low-conductivity municipal water will fail on a project that draws from a hard well; a program designed for hard well water will over-treat soft city water at unnecessary cost. The water analysis is the foundation of program design and shall not be omitted.
+
+## Required Make-Up Water Parameters
+
+The pre-design water analysis shall report at minimum the parameters listed below, by an independent laboratory using current ASTM or Standard Methods procedures. Where multiple make-up sources are possible (municipal supply normally, well water on bypass), each source shall be analyzed.
+
+```datasheet
+label: Required Pre-Design Water Analysis Parameters
+type: checkbox
+options:
+ - "pH"
+ - "Total hardness as CaCO3"
+ - "Calcium hardness as CaCO3"
+ - "Magnesium hardness as CaCO3"
+ - "Total alkalinity as CaCO3"
+ - "Chloride as Cl-"
+ - "Sulfate as SO4-2"
+ - "Silica as SiO2"
+ - "Total dissolved solids (TDS) or conductivity"
+ - "Iron, total"
+ - "Manganese"
+ - "Total organic carbon (TOC)"
+ - "Free chlorine residual (municipal supplies)"
+ - "Monochloramine residual (chloraminated supplies)"
+default: "pH"
+```
+
+```datasheet
+label: Make-Up Water Source
+type: select
+options:
+ - "Municipal potable supply (treated city water)"
+ - "On-site well — single well"
+ - "On-site well — multiple wells with blended draw"
+ - "Reclaimed water (purple-pipe non-potable supply)"
+ - "Captured rainwater or condensate"
+ - "Mixed sources — primary and bypass"
+drawing_ref: true
+default: "Municipal potable supply (treated city water)"
+```
+
+## Suitability for Cooling Tower Make-Up
+
+For projects with open cooling tower service, the make-up water shall be evaluated against CTI STD-159 acceptable limits. A make-up water with high chloride (typically above approximately 250 mg/L) or high conductivity (typically above approximately 1,000 µS/cm) limits the achievable cycles of concentration and may require softening, partial reverse osmosis, or another pretreatment before the make-up enters the tower. Where the analysis indicates the raw supply does not meet CTI STD-159 without pretreatment, the Engineer shall coordinate pretreatment equipment selection with the architectural and plumbing scope before tower selection is finalized.
+
+```datasheet
+label: Pre-Treatment of Make-Up Water (Open Systems)
+type: select
+options:
+ - "None — make-up water suitable as-is per CTI STD-159"
+ - "Softening — ion exchange for hardness reduction"
+ - "Reverse osmosis (RO) — partial or full"
+ - "Filtration — particle removal at make-up only"
+ - "Multiple — softening plus RO blend per design"
+drawing_ref: true
+default: "None — make-up water suitable as-is per CTI STD-159"
+```
+
+## Reagent and Test Water for the Service Program
+
+Test reagents and laboratory water used for in-house analysis at the project site shall meet ASTM D1193 Type II or better for general chemistry. The service provider's test kits shall use reagents traceable to recognized standards, with documented expiration dates, stored in conditions matching the manufacturer's requirements. Expired reagents shall not be used; this is a common cause of misleading low or high test results that, in turn, drive incorrect chemistry adjustments.
+
+# Pre-Operational Cleaning and Flushing
+
+## Why Pre-Operational Cleaning is Mandatory
+
+A new hydronic or condenser-water system, as installed, contains construction debris that no amount of inhibitor chemistry can remove or tolerate: cutting oils on the inside of carbon steel pipe, mill scale, weld spatter, pipe joint compound that has leached into the bore, slag and oxide from brazing, dust, drywall mud splatters that fell into open pipe before sealing, and the occasional rag or tool left in a pipe section. If these contaminants are left in the system at start-up, they migrate to the points of lowest velocity — terminal coil tubes, control valve seats, pump suction strainers, balancing valve cones — and accumulate. The inhibitor cannot establish a stable film on a metal surface that is intermittently covered by sliding debris. Within months, the system shows symptoms ranging from intermittent coil flow restriction to chronic strainer fouling to early seal failure on the pump that received the lion's share of the debris through its suction.
+
+Pre-operational cleaning is therefore mandatory for every new closed and open system covered by this standard, regardless of the construction quality of the piping installation. The cleaning procedure removes the construction debris that any installation method leaves in place. Failure to clean a system before placing it in service shall be cause for rejection of the system commissioning, and the cost of subsequent clean-out — which is significantly higher than pre-operational cleaning because the system must be disassembled in places, coils must be back-flushed individually, and the chemistry must be more aggressive — falls to the responsible party.
+
+## Cleaning Method Selection
+
+The cleaning method depends on the predominant material of construction, the system's geometry, and the anticipated nature and quantity of construction debris. Two broad approaches are used: a chemical cleaning that combines a degreasing surfactant with an alkaline builder (and, where construction debris includes mill scale or weld discoloration, an acid passivation step after the alkaline degrease), and a mechanical flushing approach that relies on high-velocity recirculation through temporary bypasses to remove debris by sweeping action alone. Most projects use a combination: an alkaline degreasing circulation followed by extended high-velocity mechanical flushing.
+
+```datasheet
+label: Pre-Operational Cleaning Method — Closed Systems
+type: select
+options:
+ - "Alkaline degreaser circulation followed by high-velocity flush (standard for new closed systems)"
+ - "Alkaline degreaser, acid clean for mill scale/weld discoloration, high-velocity flush (high-debris steel systems)"
+ - "Trisodium phosphate (TSP) flush — economical alternative for small or all-copper systems"
+ - "Mechanical flushing only — small all-copper systems where degreasing not warranted"
+default: "Alkaline degreaser circulation followed by high-velocity flush (standard for new closed systems)"
+```
+
+The historical method using trisodium phosphate (TSP) at approximately 0.5% by weight, with circulation at operating temperature, remains acceptable for small systems and for all-copper systems where cutting oil and brazing flux residue are the only significant contaminants. TSP is inexpensive, widely available, and effective; the disadvantages are that TSP discharge into a municipal sanitary sewer is restricted or prohibited in many jurisdictions because of phosphate nutrient loading. Where TSP is selected, the Contractor shall confirm discharge acceptance with the local sewer authority before circulation.
+
+```datasheet
+label: Pre-Operational Cleaning Method — Open Condenser Water Systems
+type: select
+options:
+ - "Alkaline degreaser circulation through cooling tower basin and piping, high-velocity flush"
+ - "Alkaline degreaser plus oxidizing biocide (initial microbial knockdown) followed by flush"
+ - "Mechanical flushing followed by direct online passivation (small towers with clean piping)"
+default: "Alkaline degreaser plus oxidizing biocide (initial microbial knockdown) followed by flush"
+```
+
+Open condenser water systems present an additional complication compared to closed systems: open systems are exposed to airborne contamination during construction (dust, bird debris, vegetation), and biological growth can establish itself in a cooling tower basin during the period between tower set and start-up if water has accumulated in the basin from rainfall or test water. A new open system therefore requires both a chemical degreasing step (for construction oils and dust) and an oxidizing biocide pre-treatment (for biological knockdown) before the system is placed in service with its long-term chemistry. Pre-operational biocide treatment shall be timed so that any chlorine or bromine residual is dissipated before the long-term inhibitor and biocide program begins, to avoid chemistry interference.
+
+## Flushing Velocity and Duration
+
+The flushing operation removes loosened debris by hydraulic sweeping. Effective sweeping requires a fluid velocity through every pipe segment substantially higher than design operating velocity — debris that settles in a corner at 3 ft/s requires 6 to 8 ft/s to lift and carry. In practice this is achieved either by running the system pumps with all balancing and control valves wide open and with temporary bypasses around coils (in larger systems, where pump capacity is matched to design flow plus added flush bypass), or by using a temporary high-volume flush pump connected at the central plant. The Contractor shall demonstrate by calculation that the planned flush arrangement produces a minimum velocity of 5 ft/s in every pipe section to be flushed, with 6 to 8 ft/s preferred where attainable.
+
+```datasheet
+label: Minimum Flushing Velocity
+type: range
+unit: ft/s
+options:
+ min: 3
+ max: 10
+ setpoints: [3, 4, 5, 6, 7, 8, 10]
+default: 5
+```
+
+The flush shall continue until the water at the system's lowest point (the drain valve or designated sample port) runs visibly clear and the suspended solids and iron measurements are within the acceptance criteria. A typical clean closed-system flush water analysis at acceptance shows total iron below 1 mg/L, total suspended solids below 5 mg/L, and visible clarity equivalent to ordinary tap water. A flush that does not reach these criteria after a full circulation pattern shall be repeated; persistent high iron after multiple flushes typically indicates either an active corrosion source (uncleaned mill scale, a damaged surface that needs separate treatment) or a low-velocity zone that the planned flush pattern is not reaching, both of which require investigation rather than further flushing.
+
+```datasheet
+label: Flush Acceptance Criteria
+type: checkbox
+options:
+ - "Total iron below 1 mg/L at lowest sample point"
+ - "Total suspended solids below 5 mg/L"
+ - "Visible clarity equivalent to tap water"
+ - "pH within 0.5 units of make-up water pH (cleaner residue removed)"
+ - "Conductivity within 200 µS/cm of make-up (cleaner residue removed)"
+default: "Total iron below 1 mg/L at lowest sample point"
+```
+
+## Bypassing Sensitive Equipment
+
+Coils, plate heat exchangers, control valves, and balancing valves shall be bypassed during the high-velocity flush phase, because they cannot tolerate the velocity required for effective sweeping and because the small flow paths in these components are precisely the locations where mobilized debris will lodge if it is allowed to pass through. The Contractor shall install temporary spool pieces or flush jumpers across each coil and across each major heat exchanger before the flush begins; these temporary connections shall be removed and the equipment reconnected to the system only after the flush is complete and accepted. The same precaution applies to control valves and balancing valves at terminal units in branch piping; these shall be bypassed by temporary jumpers or removed entirely during the branch flush.
+
+Where the project budget or schedule does not allow individual coil bypasses (smaller projects with many terminals), the alternative is to install a temporary fine-mesh strainer (typically 100 mesh or finer) immediately upstream of each coil bank to catch debris before it reaches the coil, and to clean the strainer on a programmed interval during the flush. This is less effective than full bypass — debris still reaches the strainer at coil-inlet velocity, with some passing through the strainer — but is materially better than no precaution.
+
+## Discharge of Flush Water
+
+Flush water carries cleaner chemistry, mobilized debris, and possibly elevated iron and copper. The Contractor shall coordinate discharge with the local sanitary sewer authority and shall obtain any required discharge permit before flushing. Discharge directly to storm sewer is generally prohibited because of the cleaner chemistry and metals content. Discharge to a sanitary sewer is usually acceptable for diluted alkaline cleaners but may be restricted for acid cleaners, phosphate-based cleaners, or where biocide residual is present. Some projects with large cleaning volumes require neutralization or sequestration of the flush water in a temporary tank before discharge.
+
+```datasheet
+label: Flush Water Discharge Route
+type: select
+options:
+ - "Sanitary sewer per local authority acceptance (typical)"
+ - "Sanitary sewer after neutralization to pH 6–9"
+ - "Off-site disposal as regulated waste (acid cleaner residue, biocide residue)"
+ - "On-site evaporation pond (rare, project-specific)"
+drawing_ref: true
+default: "Sanitary sewer per local authority acceptance (typical)"
+```
+
+# Pre-Passivation
+
+## Purpose
+
+Once the system has been cleaned of construction debris and flushed clear, the metal surfaces are bright and active — chemically reactive and ready to either form a stable protective oxide layer (passivation) or to begin corroding (rust formation, copper oxidation). The window between completion of flushing and the establishment of a stable passive layer is short — within hours, freshly exposed carbon steel begins to flash-rust if exposed to oxygen-bearing water without inhibitor present. Pre-passivation is the chemistry step that establishes the protective oxide layer under controlled conditions, with the system intentionally dosed at higher inhibitor concentration than the long-term operating level, circulating at a specific temperature for a specific time. Done well, pre-passivation creates a uniform, dense protective film on all carbon steel internal surfaces that resists oxygen corrosion for the life of the system. Done badly or omitted, the system establishes a partial, irregular film, and the unprotected zones become initiation sites for pitting that persists despite a correct long-term inhibitor concentration.
+
+## Pre-Passivation Procedure — Closed Hydronic Systems
+
+After flushing acceptance and immediately before placing the system into operating service, the system shall be refilled with treated make-up water and dosed with the pre-passivation chemistry. The dose is typically 2 to 3 times the long-term operating inhibitor level. The system shall be circulated continuously at near operating temperature — typically 100°F to 140°F for HHW systems, or ambient with circulation pumps running for CHW systems — for a minimum of 24 hours. Where the system has carbon steel as the predominant material, 48 to 72 hours is preferred. During passivation, sample-port readings shall confirm that inhibitor concentration remains within the design range across the entire system (no zones short on inhibitor due to high consumption from un-passivated surfaces), and pH shall remain within the design range.
+
+```datasheet
+label: Pre-Passivation Inhibitor Dose Multiplier (vs. Long-Term Operating Concentration)
+type: range
+unit: × operating level
+options:
+ min: 1.5
+ max: 5
+ setpoints: [1.5, 2, 2.5, 3, 4, 5]
+default: 2.5
+```
+
+```datasheet
+label: Pre-Passivation Circulation Time
+type: range
+unit: hours
+options:
+ min: 12
+ max: 168
+ setpoints: [12, 24, 36, 48, 72, 96, 168]
+default: 48
+```
+
+```datasheet
+label: Pre-Passivation Circulation Temperature — HHW
+type: range
+unit: °F
+options:
+ min: 70
+ max: 180
+ setpoints: [70, 100, 120, 140, 160, 180]
+default: 120
+```
+
+After the passivation period, the system inhibitor level shall be drawn down to the long-term operating concentration by a controlled drain-and-replace or by simply allowing system make-up to dilute over the first weeks of operation. The corrosion coupons installed at the start of passivation shall be left in place during the long-term operation and removed at the first scheduled inspection — typically 90 days — to verify passivation success.
+
+## Pre-Passivation — Open Condenser Water Systems
+
+Open systems are passivated more rapidly than closed systems because the higher dissolved oxygen content and the higher inhibitor circulation rate establish the protective film quickly. A typical open-tower passivation runs at 1.5 to 2 times the long-term inhibitor level for 24 to 48 hours of circulation with the tower fan off (or running on minimum speed) to limit evaporation during passivation. The cycles of concentration during passivation are intentionally held low — close to 1.5 — by elevated bleed-off, so that the passivation chemistry remains close to the dosed level and is not concentrated to a damaging level.
+
+```datasheet
+label: Pre-Passivation — Open System Bleed Strategy
+type: radio
+options:
+ - "Manual bleed to hold conductivity near make-up + 200 µS/cm during passivation"
+ - "Conductivity controller set to 1.5 COC during passivation, then reset to operating COC"
+ - "No bleed during passivation, accept rising cycles for shortened passivation period"
+default: "Conductivity controller set to 1.5 COC during passivation, then reset to operating COC"
+```
+
+# Closed System Chemical Treatment
+
+## Inhibitor Chemistry Selection
+
+The inhibitor program for a closed hydronic system depends on the predominant metallurgy and the operating temperature. The most common chemistries are molybdate, nitrite, and combinations of these with azole copper-corrosion inhibitor and polymer dispersant. Each has characteristic strengths and limitations; the program designer's job is to match the chemistry to the system and to the Owner's preferences regarding monitoring complexity, ecological discharge concerns, and cost.
+
+```datasheet
+label: Closed System Primary Corrosion Inhibitor
+type: select
+options:
+ - "Molybdate — non-oxidizing, broad metallurgy, low toxicity, easy to test (preferred for most new closed systems)"
+ - "Nitrite — well-established, lower cost, but bacteria-mediated depletion possible"
+ - "Molybdate + nitrite blend — synergistic, lower total concentration than either alone"
+ - "Phosphonate + azole + polymer — for systems with aluminum or mixed metallurgy"
+ - "Silicate — historical, used primarily in glycol systems"
+default: "Molybdate — non-oxidizing, broad metallurgy, low toxicity, easy to test (preferred for most new closed systems)"
+```
+
+Molybdate-based inhibitors form a passive film on carbon steel surfaces through an oxidative mechanism that does not depend on oxygen scavenging, are stable across a wide pH and temperature range, are non-toxic at use concentrations, are not affected by chloride to the same extent that nitrite is, and have a straightforward colorimetric or electrochemical test method. The disadvantages are higher unit cost than nitrite, the requirement for higher pH (typically 8.5 to 10.5) to maintain protection on copper surfaces, and a long-term ecological concern with molybdate discharge to surface waters in some jurisdictions that limits the program's discharge route.
+
+Nitrite-based inhibitors are the historical standard, widely used in commercial HHW and CHW systems since the 1960s. Nitrite is effective on carbon steel at concentrations of 500 to 1,000 mg/L as NO2-, is inexpensive, and tests easily by both colorimetric and titration methods. The principal vulnerability is biological: certain bacteria (Pseudomonas, Nitrosomonas, Nitrobacter) consume nitrite as an energy source and can deplete nitrite concentration from 800 mg/L to below 50 mg/L within weeks under favorable conditions, leaving the system without effective corrosion protection. Where nitrite is selected, the program shall include routine microbial monitoring and a non-oxidizing biocide rotation to suppress nitrite-consuming organisms.
+
+Phosphonate-and-polymer chemistries are used in mixed-metallurgy systems and in systems with aluminum components that cannot tolerate the higher pH of molybdate or nitrite programs. The phosphonate provides primary corrosion inhibition; an azole (typically tolyltriazole, TT, or benzotriazole, BZT) protects copper and copper alloys; the polymer dispersant prevents scale precipitation in localized hot zones. These programs are more complex to test and to dose, but are the appropriate choice where aluminum cylinders, aluminum-cored heat exchangers, or aluminum impellers are in contact with the treated water.
+
+## Copper Corrosion Inhibitor (Azole)
+
+Where the system contains copper or copper-alloy components — which includes essentially all commercial systems — an azole copper inhibitor shall be added regardless of the primary chemistry. Tolyltriazole (TT) is the standard, dosed at 5 to 15 mg/L; benzotriazole (BZT) and mercaptobenzothiazole (MBT) are alternatives. The azole forms a chemisorbed film on copper surfaces that inhibits both copper dissolution and the redeposition of copper ions on carbon steel (where they would act as cathodes and accelerate steel corrosion). Azole is consumed by oxidizing biocides; in any closed system where an oxidizing biocide rotation is part of the program, azole feed shall be timed to follow the biocide treatment, and azole concentration shall be tested before and after biocide events.
+
+```datasheet
+label: Copper Corrosion Inhibitor (Azole)
+type: radio
+options:
+ - "Tolyltriazole (TT) — standard, 5–15 mg/L"
+ - "Benzotriazole (BZT) — alternative where TT availability is limited"
+ - "Halogen-stable azole — required where oxidizing biocides are used"
+ - "Not required — system contains no copper or copper alloys (rare)"
+default: "Tolyltriazole (TT) — standard, 5–15 mg/L"
+```
+
+## Polymer Dispersant
+
+A polymer dispersant — typically a polyacrylate, polymethacrylate, or polymaleic acid copolymer — shall be included in the closed-system program at 5 to 20 mg/L. The polymer keeps any suspended iron oxide, scale particles, and microbial debris in suspension so that the side-stream filter can capture them rather than allowing settled deposit at low-velocity zones. The polymer also provides crystal-modification action on any incipient scale, distorting the crystal growth pattern so that scale does not adhere to heat-transfer surfaces.
+
+## Control Ranges — Closed System
+
+The long-term operating control ranges for a closed system depend on the chemistry selected. Typical ranges for the most common closed-system chemistries are summarized in the datasheet below; the service provider's recommendation governs the project-specific control range, and field test results shall be compared against this range at each service visit.
+
+```datasheet
+label: Closed System Control Range — Inhibitor Concentration
+type: select
+options:
+ - "Molybdate — 200–400 mg/L as MoO4-2"
+ - "Nitrite — 700–1,200 mg/L as NO2-"
+ - "Molybdate + Nitrite — 100 mg/L Mo + 400 mg/L NO2 minimum"
+ - "Phosphonate — 5–15 mg/L as PO4 active phosphonate"
+ - "Per service provider's design"
+default: "Molybdate — 200–400 mg/L as MoO4-2"
+```
+
+```datasheet
+label: Closed System pH Range
+type: select
+options:
+ - "8.5–10.5 (molybdate or nitrite chemistry, no aluminum present)"
+ - "8.0–9.0 (phosphonate chemistry, mixed metallurgy or aluminum)"
+ - "9.0–10.0 (nitrite chemistry, biological inhibition support)"
+default: "8.5–10.5 (molybdate or nitrite chemistry, no aluminum present)"
+```
+
+```datasheet
+label: Closed System Conductivity Tracking
+type: radio
+options:
+ - "Tracked at each service visit; trend used to detect leaks (rising) or dilution (falling)"
+ - "Not tracked as a control parameter (chemistry tested directly)"
+default: "Tracked at each service visit; trend used to detect leaks (rising) or dilution (falling)"
+```
+
+## Closed-Loop Biocide
+
+Closed systems are not free of biological activity, particularly when nitrite chemistry is in use. A non-oxidizing biocide — typically isothiazolone, glutaraldehyde, or a quaternary ammonium compound (quat) — shall be added on a programmed rotation (typically every 90 to 180 days) where biological inhibition is required. Oxidizing biocides (chlorine, bromine) are generally not used in closed systems because of their interaction with corrosion inhibitors and elastomer attack at the concentrations needed. The biocide rotation shall use at least two different active ingredients on alternating cycles, to suppress development of resistant organisms.
+
+```datasheet
+label: Closed System Biocide Program
+type: select
+options:
+ - "Isothiazolone rotation (every 120 days)"
+ - "Glutaraldehyde rotation (every 90 days)"
+ - "Two-product rotation (isothiazolone alternating with glutaraldehyde)"
+ - "Not required — system shows no microbial activity history and is fully closed"
+default: "Two-product rotation (isothiazolone alternating with glutaraldehyde)"
+```
+
+# Open System Chemical Treatment
+
+## Why Open Systems Are Different
+
+An open recirculating condenser water system loses water continuously by evaporation through the cooling tower fill. Each pass through the tower removes water and leaves the dissolved solids behind in the remaining inventory. Without bleed-off (intentional drain of concentrated water), the dissolved solids would concentrate without limit, scaling and corroding rapidly. With controlled bleed-off, the system reaches a stable "cycles of concentration" — the ratio of dissolved solids in the recirculating water to dissolved solids in the make-up water — typically between 3 and 6 cycles for most projects, with up to 10 cycles achievable when make-up quality and tower design permit. The treatment program for an open system therefore comprises four interlocking elements: a scale inhibitor that suppresses calcium carbonate, calcium sulfate, and silica scale at concentrated conditions; a corrosion inhibitor that maintains protection of the carbon steel, copper, and galvanized surfaces in the loop; a biocide program that prevents biological growth in the tower fill, basin, and piping; and a conductivity-controlled bleed system that maintains cycles of concentration at the design point without manual intervention.
+
+In addition, open systems are subject to ASHRAE Standard 188's Legionellosis risk management requirements. The treatment program is not only an asset-protection program but a public-health control measure. Treatment parameters, sampling protocols, and corrective actions are part of the building's Water Management Plan, and the documentation supporting them shall be maintained as part of building records.
+
+## Scale Inhibitor
+
+Open system scale inhibition is typically based on phosphonate chemistry (HEDP — 1-hydroxyethylidene-1,1-diphosphonic acid; PBTC — phosphonobutane tricarboxylic acid; ATMP — amino tris methylene phosphonic acid) combined with a polymer dispersant. The phosphonate provides threshold inhibition — preventing crystal nucleation and growth at concentrations well below stoichiometric — while the polymer modifies crystal habit and keeps suspended solids dispersed. At higher cycles of concentration (typically above 5 cycles) or with high-silica make-up water, supplemental silica scale inhibitor may be required.
+
+```datasheet
+label: Open System Scale Inhibitor
+type: select
+options:
+ - "Phosphonate (HEDP or PBTC) plus polymer dispersant (standard for most open systems)"
+ - "Phosphonate plus polymer plus silica inhibitor (high-silica make-up, > 100 mg/L SiO2)"
+ - "All-organic (polymer-only) — phosphate-discharge-restricted jurisdictions"
+default: "Phosphonate (HEDP or PBTC) plus polymer dispersant (standard for most open systems)"
+```
+
+## Corrosion Inhibitor — Open Systems
+
+Open system corrosion control uses lower inhibitor concentrations than closed systems because the inhibitors are continuously lost to bleed-off. The standard approach combines a phosphate or zinc-phosphate steel inhibitor at 2 to 6 mg/L (as PO4) with an azole copper inhibitor at 1 to 3 mg/L (as TT) and the polymer dispersant that supports the scale inhibitor. Where galvanized steel cooling towers are present, "white rust" prevention requires careful control: the pH shall be held between 7.0 and 8.0 during the first three to six months of operation while the zinc surface develops its protective patina, after which the pH range may rise to 8.0 to 9.0 for long-term operation. Aggressive pH excursions above 9.5 in the first weeks of operation cause rapid loss of the zinc coating and shall be prevented.
+
+```datasheet
+label: Open System Corrosion Inhibitor
+type: select
+options:
+ - "Phosphate plus azole plus polymer (standard mild-steel-and-copper towers)"
+ - "Zinc-phosphate plus azole plus polymer (galvanized towers, white-rust prevention)"
+ - "All-organic phosphate-free formulation (phosphate-discharge-restricted jurisdictions)"
+default: "Phosphate plus azole plus polymer (standard mild-steel-and-copper towers)"
+```
+
+```datasheet
+label: New Galvanized Tower — Initial Operation pH (Months 1–3)
+type: range
+unit: pH units
+options:
+ min: 7.0
+ max: 9.0
+ setpoints: [7.0, 7.2, 7.5, 7.8, 8.0, 8.2, 8.5, 9.0]
+default: 7.5
+```
+
+## Biocide Program — Open Systems
+
+Open system biocide programs combine an oxidizing biocide (continuous low-dose or periodic shock) with a non-oxidizing biocide on a rotational schedule. The oxidizing biocide is typically chlorine (sodium hypochlorite) or bromine (sodium bromide activated by hypochlorite, or stabilized bromine donor); the non-oxidizing biocide is selected from isothiazolone, glutaraldehyde, dibromonitrilopropionamide (DBNPA), or quaternary ammonium compounds. The two classes are alternated to suppress development of resistant organisms and to maintain biocide effectiveness against the broadest range of microbial species. The biocide program is the primary engineering control for Legionella in the cooling tower water, and its proper design and documentation is the principal mechanism by which the project demonstrates compliance with ASHRAE 188 for the open system.
+
+```datasheet
+label: Open System Biocide Program
+type: select
+options:
+ - "Continuous low-dose halogen (chlorine or bromine) plus non-oxidizing rotation"
+ - "Slug-dose halogen on schedule plus non-oxidizing rotation"
+ - "ORP-controlled halogen plus non-oxidizing rotation (preferred — feedback control)"
+ - "Stabilized bromine donor plus non-oxidizing rotation"
+ - "Per ASHRAE 188 Water Management Plan and service provider's design"
+default: "ORP-controlled halogen plus non-oxidizing rotation (preferred — feedback control)"
+```
+
+```datasheet
+label: Oxidizing Biocide Selection
+type: radio
+options:
+ - "Sodium hypochlorite (chlorine) — economical, broad-spectrum"
+ - "Activated sodium bromide (bromine) — better performance at high pH"
+ - "Stabilized halogen donor (chlorinated or brominated hydantoin) — slug or feeder-tablet"
+ - "Chlorine dioxide — high-biofilm-penetration applications"
+default: "Activated sodium bromide (bromine) — better performance at high pH"
+```
+
+Bromine is generally preferred over chlorine for open cooling towers operating in the typical alkaline pH range (8.0 to 9.0) because hypobromous acid (HOBr) is the dominant species at these pH values and is a more effective biocide than the corresponding hypochlorous acid (HOCl) which dissociates to less-active hypochlorite (OCl-) at higher pH. Chlorine remains an effective and economical choice for systems running below pH 8.0 or where pH is intentionally controlled lower for galvanized tower protection.
+
+```datasheet
+label: Non-Oxidizing Biocide Rotation
+type: checkbox
+options:
+ - "Isothiazolone (broad-spectrum, low pH dependence)"
+ - "Glutaraldehyde (effective against sulfate-reducing bacteria)"
+ - "DBNPA (rapid-acting, short half-life, low residual)"
+ - "Quaternary ammonium compound (surfactant action, biofilm penetration)"
+ - "THPS — tetrakis(hydroxymethyl)phosphonium sulfate (anaerobe control)"
+default: "Isothiazolone (broad-spectrum, low pH dependence)"
+```
+
+## Cycles of Concentration and Conductivity Control
+
+The target cycles of concentration for the open system shall be established by the service provider based on make-up water quality, the most limiting scale-or-corrosion control parameter (typically calcium hardness × alkalinity product, or chloride concentration at concentrated conditions), and the Owner's water-conservation goals. Higher cycles save make-up water and reduce blowdown discharge volume but concentrate dissolved solids and increase the burden on scale and corrosion inhibitors. For typical municipal make-up water of moderate hardness, target cycles of 4 to 6 are common; for soft, low-conductivity make-up water, cycles of 6 to 10 are achievable; for hard well water, cycles may be limited to 2 to 3 before scale or chloride control becomes the constraint.
+
+```datasheet
+label: Target Cycles of Concentration
+type: range
+unit: cycles
+options:
+ min: 2
+ max: 10
+ setpoints: [2, 3, 4, 5, 6, 7, 8, 10]
+default: 5
+```
+
+Conductivity control is the operational mechanism that maintains cycles of concentration. A conductivity probe immersed in the recirculating water (typically in the tower basin or in a side-stream sample loop) signals the conductivity controller. When conductivity rises above the set point — corresponding to the target cycles — the controller energizes a bleed-off solenoid valve, allowing concentrated water to drain to the sewer. When conductivity falls below the set point — through normal evaporation losing pure water and concentrating dissolved solids — the bleed valve closes. Make-up water flows in automatically through the float-controlled make-up valve to replace the water lost to bleed and evaporation. The conductivity controller and the chemical feed pumps are typically integrated so that chemical addition is proportional to make-up water flow (water-meter pulse signal) or proportional to bleed events (each bleed triggers a corresponding chemistry dose), maintaining inhibitor and biocide concentration despite the continuous loss to bleed.
+
+```datasheet
+label: Conductivity Controller Configuration
+type: select
+options:
+ - "Standalone controller with conductivity setpoint and bleed solenoid output"
+ - "Combined conductivity/ORP/pH controller (multi-parameter integrated)"
+ - "BAS-integrated multi-parameter controller with remote access and trending"
+default: "BAS-integrated multi-parameter controller with remote access and trending"
+```
+
+```datasheet
+label: Chemical Feed Pacing
+type: radio
+options:
+ - "Make-up water meter pulse — chemicals dosed proportional to make-up volume"
+ - "Bleed event paced — chemicals dosed when bleed solenoid energizes"
+ - "Continuous feed at fixed rate — least preferred, manual chemistry adjustment required"
+default: "Make-up water meter pulse — chemicals dosed proportional to make-up volume"
+```
+
+## ORP (Oxidation-Reduction Potential) Control of Oxidizing Biocide
+
+Where oxidizing biocide feed is automatically controlled, the preferred control parameter is oxidation-reduction potential (ORP), measured in millivolts by an in-line ORP probe. ORP correlates well with the biocidal effectiveness of free halogen residual, integrates the effect of pH on halogen species, and responds rapidly to demand changes (consumed by biofilm, organic load, ambient debris). Typical control ranges are 600 to 750 mV for active biocidal residual in the recirculating water. The ORP set point shall be established by the service provider based on the specific oxidizing chemistry and verified by free halogen residual measurement at the corresponding ORP reading; a calibration curve relating ORP to free halogen residual shall be established and verified at least quarterly.
+
+```datasheet
+label: ORP Control Setpoint Range
+type: range
+unit: mV
+options:
+ min: 400
+ max: 900
+ setpoints: [400, 500, 550, 600, 650, 700, 750, 800, 900]
+default: 650
+```
+
+# Glycol Systems
+
+## When Glycol is Used
+
+Glycol — propylene glycol (PG) or ethylene glycol (EG) — is added to closed hydronic loops to provide freeze protection in piping or equipment that may experience temperatures below 32°F. Typical applications include rooftop and outdoor piping in cold climates, ground-source heat pump loops where the source temperature falls below freezing under high-load conditions, and snowmelt loops by design. The glycol concentration is selected by the design freeze temperature with a safety margin: 30% PG provides protection to approximately 0°F; 40% PG to approximately -15°F; 50% PG to approximately -30°F. Concentration is selected on the basis of "burst protection" (lowest concentration at which the fluid does not split a pipe even if it gels) or "flow protection" (higher concentration at which the fluid remains pumpable at the cold temperature); flow protection is appropriate for systems that must continue operating at the cold extreme, burst protection for systems that can tolerate intermittent gelling but not pipe damage.
+
+## Glycol Selection — Propylene vs. Ethylene
+
+Propylene glycol (PG) is preferred for HVAC service because of its lower toxicity profile (PG is generally recognized as safe for incidental food contact at low concentrations), which simplifies storage, spill response, and accidental cross-connection consequences. Ethylene glycol (EG) has slightly better heat-transfer properties — lower viscosity at low temperatures — but is toxic if ingested and is restricted by many plumbing codes from use in any building where any cross-connection to potable water is possible. Most commercial HVAC projects use PG; EG is reserved for industrial process loops, district energy plants, and snowmelt systems where toxicity hazard is managed by the system design.
+
+```datasheet
+label: Glycol Type
+type: radio
+options:
+ - "Propylene glycol (PG) — preferred for HVAC service, low toxicity"
+ - "Ethylene glycol (EG) — high-performance heat transfer, restricted by some codes"
+default: "Propylene glycol (PG) — preferred for HVAC service, low toxicity"
+```
+
+## Glycol Quality — Inhibited Industrial Grade
+
+Glycol for HVAC service shall be inhibited industrial grade — that is, the glycol product is pre-formulated with corrosion inhibitors selected for hydronic service. Uninhibited or automotive glycol shall not be used: automotive glycol contains inhibitors selected for the materials in an automotive cooling system (copper, brass, aluminum, with frequent fluid replacement) which are not optimal for a building hydronic system (carbon steel, copper, with multi-year service life), and the dyes and bittering agents in automotive glycol can interfere with field testing. Uninhibited glycol provides no corrosion protection at all and shall be treated as a system fill chemistry separately. The product shall be confirmed compatible with all wetted materials including the system's primary inhibitor chemistry if one is also present.
+
+```datasheet
+label: Glycol Product Grade
+type: radio
+options:
+ - "Inhibited industrial grade — pre-formulated with HVAC-appropriate inhibitors"
+ - "Inhibited industrial grade plus supplemental azole and biocide rotation"
+ - "Uninhibited grade — separate inhibitor program required (rare, project-specific)"
+default: "Inhibited industrial grade — pre-formulated with HVAC-appropriate inhibitors"
+```
+
+```datasheet
+label: Glycol Concentration
+type: range
+unit: % by volume
+options:
+ min: 20
+ max: 50
+ setpoints: [20, 25, 30, 35, 40, 45, 50]
+drawing_ref: true
+default: 30
+```
+
+## Glycol Degradation and Testing
+
+Glycol degrades slowly under hydronic service conditions, particularly at the elevated temperatures typical of HHW operation. The degradation produces organic acids that lower system pH and increase corrosion aggressiveness. The inhibitor package in inhibited industrial glycol includes a reserve alkalinity buffer that neutralizes these acids; over time, the buffer is consumed and the inhibitor package depletes. Glycol systems shall be tested at each service visit for pH, inhibitor reserve, and glycol concentration (by refractometer); when inhibitor reserve is depleted (indicated by pH drift below the design range despite stable glycol concentration), the system shall be either fully recharged with fresh inhibited glycol or supplemented with concentrated inhibitor package, per the glycol manufacturer's recommendation.
+
+```datasheet
+label: Glycol System Test Parameters at Each Service Visit
+type: checkbox
+options:
+ - "pH"
+ - "Glycol concentration (refractometer)"
+ - "Inhibitor reserve (per glycol manufacturer's test method)"
+ - "Conductivity (trend for leak detection)"
+ - "Total iron, total copper (annual)"
+ - "Biological activity (annual, where applicable)"
+default: "pH"
+```
+
+# Steam and Condensate Treatment
+
+## Scope
+
+The steam and condensate treatment program covered here applies to low-pressure (15 psig) and medium-pressure (up to 150 psig) steam systems serving humidifiers, sterilizers, kitchen equipment, and heating boilers. The program addresses three regions of the system: the boiler water, where dissolved solids concentrate and where scale, corrosion, and carryover are controlled; the steam itself, where amines and neutralizers control condensate-line corrosion; and the condensate return, where carbonic acid attack of carbon steel return piping is the principal corrosion mechanism. High-pressure steam systems above 150 psig are outside the scope of this standard and shall use a process-grade boiler water program designed under separate cover.
+
+## Boiler Water — Pre-Boiler and Internal Treatment
+
+Steam boilers concentrate dissolved solids similarly to open cooling towers: water enters as feed, steam exits as vapor, and dissolved solids remain in the boiler. Cycles of concentration are managed by blowdown, either continuous (a small bleed from the surface of the boiler water) or intermittent (manual blow from the mud drum). The boiler water program comprises three elements: a pre-boiler oxygen scavenger that removes residual dissolved oxygen from the feedwater (typically sulfite or DEHA — diethyl hydroxylamine); an internal phosphate or polymer treatment that conditions any remaining hardness and prevents scale on heating surfaces; and an alkalinity builder (typically caustic) that maintains boiler water pH in the protective range (typically 10.5 to 11.5).
+
+```datasheet
+label: Boiler Feedwater Pretreatment
+type: select
+options:
+ - "Softening (ion exchange) — standard for boilers above 15 psig"
+ - "Softening plus deaeration (mechanical oxygen removal)"
+ - "Softening plus reverse osmosis (low-conductivity makeup, high cycles)"
+ - "None — small low-pressure heating boilers only"
+default: "Softening (ion exchange) — standard for boilers above 15 psig"
+```
+
+```datasheet
+label: Boiler Water Oxygen Scavenger
+type: radio
+options:
+ - "Sulfite — economical, suited to non-food-contact steam"
+ - "DEHA — diethyl hydroxylamine, food-grade per FDA 21 CFR 173.310"
+ - "Erythorbic acid — food-grade alternative"
+default: "Sulfite — economical, suited to non-food-contact steam"
+```
+
+```datasheet
+label: Boiler Internal Treatment
+type: select
+options:
+ - "Phosphate program — chelant or coordinated phosphate for hardness conditioning"
+ - "All-polymer program — polymeric dispersant only, for soft-water boilers"
+ - "Phosphate plus polymer — combined hardness conditioning and sludge dispersion"
+default: "Phosphate plus polymer — combined hardness conditioning and sludge dispersion"
+```
+
+## Steam Line Amines
+
+Steam carries volatile components that condense in the return-line piping along with the condensed water. The principal aggressor in condensate is carbonic acid (H2CO3), formed when carbon dioxide — released from carbonate alkalinity in the boiler water — dissolves in the condensate. Carbonic acid lowers condensate pH to as low as 5.0 to 5.5, which aggressively attacks carbon steel condensate return piping, causing grooving corrosion at the bottom of horizontal returns where condensate collects. The control measure is to add a volatile amine — typically morpholine, cyclohexylamine, or DEAE (diethylaminoethanol) — to the boiler water; the amine volatilizes with the steam, condenses with the water, and neutralizes the carbonic acid to maintain condensate pH at 8.5 to 9.0. The selection of amine depends on its distribution ratio (the proportion that ends up at the first vs. last condensing point in the system) and on whether the steam contacts food, where FDA 21 CFR 173.310 limits the allowable amines.
+
+```datasheet
+label: Steam Line Amine
+type: select
+options:
+ - "Cyclohexylamine — broad distribution, standard non-food steam"
+ - "Morpholine — concentrates at first condensing point, suited to short-distribution systems"
+ - "DEAE — diethylaminoethanol, broad distribution"
+ - "Blend of two amines — tailored distribution across long steam mains"
+ - "Per FDA 21 CFR 173.310 list — food-contact steam"
+default: "Cyclohexylamine — broad distribution, standard non-food steam"
+```
+
+## Condensate Sampling
+
+Condensate quality shall be tested at the condensate receiver and at any sampling point representative of the longest return-line distance. Test parameters include pH (control range 8.5 to 9.0), conductivity (trend), and total iron (high iron indicates active return-line corrosion). Where condensate iron exceeds 1 mg/L, the amine dose shall be increased and the distribution of amine reviewed; persistently high iron despite correct pH indicates either dissolved-oxygen ingress at the receiver (correctable by venting and air-tightness) or under-amination at the most distant returns.
+
+```datasheet
+label: Condensate Quality Control Range
+type: select
+options:
+ - "pH 8.5–9.0, iron < 1 mg/L (standard heating and humidification)"
+ - "pH 8.0–8.5, iron < 0.5 mg/L (food-contact steam, where amine is limited)"
+default: "pH 8.5–9.0, iron < 1 mg/L (standard heating and humidification)"
+```
+
+# Equipment — Feeders, Controllers, Filtration
+
+## Chemical Feed Pumps
+
+Chemical feed pumps deliver inhibitor, biocide, and scale chemistry from bulk or drum storage into the treated water. The standard pump for HVAC water treatment service is a peristaltic, diaphragm, or solenoid-actuated metering pump with adjustable stroke length, adjustable stroke frequency, and a pulse input for pacing by water meter or controller signal. Each chemical product shall have its own dedicated feed pump and feed line; chemicals shall not share feed lines because of cross-contamination risk in the suction tube and because of incompatibility between products (acid and oxidizer, oxidizer and reducing agent). Feed pumps shall be located within secondary containment, with feed lines routed in plain view and labeled at each end with the chemical product, the feeding pump tag, and the receiving system tag. Calibration columns shall be provided on each feed pump suction to verify dose volume against expected delivery.
+
+```datasheet
+label: Chemical Feed Pump Type
+type: select
+options:
+ - "Diaphragm metering pump (standard, broad chemical compatibility)"
+ - "Peristaltic pump (preferred for low-flow accurate dosing and chemicals that gas off)"
+ - "Solenoid-actuated metering pump (economical, suited to small systems)"
+ - "Pneumatically operated drum pump (large-volume bulk feed)"
+default: "Diaphragm metering pump (standard, broad chemical compatibility)"
+```
+
+```datasheet
+label: Chemical Feed Pacing Signal Source
+type: select
+options:
+ - "Make-up water meter contact-pulse output (volumetric pacing)"
+ - "Conductivity or ORP controller proportional output (residual pacing)"
+ - "Manual rate, set during commissioning and adjusted during service visits"
+ - "BAS-controlled pulse via [[sync/building-automation-system]]"
+default: "Make-up water meter contact-pulse output (volumetric pacing)"
+```
+
+## Solid Chemical Feeders
+
+Solid (puck, tablet, briquette) chemical feeders are an alternative to liquid bulk feed for some chemistries, particularly for low-cycle stabilized halogen donors in small open systems and for inhibitor pucks in some closed systems. Solid feeders eliminate the need for a chemical-storage room with bulk tanks and provide longer service intervals between chemical replenishment, but they offer less precise dose control and require manual top-up rather than automatic bulk-tank refilling. Solid feeders are appropriate for small projects, for projects in space-constrained mechanical rooms, and for Owners who prefer the simpler service model.
+
+```datasheet
+label: Chemical Feed Equipment — Bulk vs. Solid
+type: radio
+options:
+ - "Bulk liquid feed with metering pumps (standard for medium and large projects)"
+ - "Solid feeders (pucks, tablets) for inhibitor and halogen donor"
+ - "Combination — bulk inhibitor with solid halogen donor (common compromise)"
+default: "Bulk liquid feed with metering pumps (standard for medium and large projects)"
+```
+
+## Conductivity and ORP Controllers
+
+The conductivity and ORP controller is the operational brain of an automatic chemical feed program. Modern controllers integrate conductivity measurement, ORP measurement, pH measurement (where required), water-meter pulse counting, multiple chemical-feed pump outputs, bleed-off solenoid output, alarm contacts, and a communication port (typically Modbus RTU or BACnet) to the building automation system. The controller shall provide local display of all measured parameters and recent trend data, remote alarm output for any critical parameter excursion, and a logging function that retains parameter history for at least 30 days locally and longer via BAS integration.
+
+```datasheet
+label: Controller Capabilities Required
+type: checkbox
+options:
+ - "Conductivity measurement with isolated probe"
+ - "ORP measurement (open systems with oxidizing biocide)"
+ - "pH measurement"
+ - "Make-up water meter pulse input"
+ - "Bleed-off solenoid output with flow verification"
+ - "Multiple chemical pump pacing outputs"
+ - "Alarm output for parameter excursion"
+ - "BAS communication (BACnet, Modbus, or LonWorks)"
+ - "Local 30-day data logging"
+ - "Remote web-based access for service provider"
+default: "Conductivity measurement with isolated probe"
+```
+
+Controller probes — conductivity, ORP, pH — require routine calibration against reference solutions. Calibration intervals are typically 30 days for ORP and pH probes (which drift more rapidly), and 90 days for conductivity probes. Calibration solutions, calibration logs, and probe replacement records shall be maintained as part of the service contract. Probes that fail to hold calibration shall be replaced rather than re-calibrated repeatedly; an out-of-calibration probe drives wrong chemistry adjustments that, in turn, damage the system.
+
+## Side-Stream Filtration
+
+Side-stream filtration continuously removes suspended solids — iron oxide, calcium scale fines, biological debris, airborne dirt that enters through the cooling tower — from a portion of the recirculating water. A filter is "side-stream" because it processes a fraction of the recirculation flow (typically 5% to 10%) rather than the full flow; this approach achieves effective particle removal over time without the pressure drop and equipment size penalty of full-flow filtration. Side-stream filtration is mandatory for open systems under this standard and strongly recommended for large closed systems.
+
+```datasheet
+label: Side-Stream Filtration Type — Open Systems
+type: select
+options:
+ - "Sand filter — 5 to 15 micron nominal (broad particle range, backwashable)"
+ - "Centrifugal separator — 30+ micron (high-density particles, no media replacement)"
+ - "Bag filter — 5 to 25 micron (economical, manual change-out)"
+ - "Cartridge filter — 5 to 10 micron (fine filtration, manual change-out)"
+ - "Disk filter — 10 to 100 micron (backwashable, intermediate performance)"
+default: "Sand filter — 5 to 15 micron nominal (broad particle range, backwashable)"
+```
+
+```datasheet
+label: Side-Stream Filtration Type — Closed Systems (Where Provided)
+type: select
+options:
+ - "Bag filter — 5 to 25 micron (standard, easy change-out)"
+ - "Cartridge filter — 1 to 10 micron (fine filtration where required)"
+ - "Centrifugal separator — 30+ micron (high iron-oxide load)"
+ - "Not provided — system small enough that combination air/dirt separator suffices"
+default: "Bag filter — 5 to 25 micron (standard, easy change-out)"
+```
+
+```datasheet
+label: Side-Stream Flow Rate as Percent of System Flow
+type: range
+unit: %
+options:
+ min: 1
+ max: 15
+ setpoints: [1, 3, 5, 7, 10, 12, 15]
+default: 5
+```
+
+Side-stream flow shall be drawn from a location with representative particle loading — typically immediately downstream of the system's lowest-velocity zone where particles are most likely to settle — and returned to a different location to encourage circulation through the filter rather than direct recycle. For open systems, the side-stream filter draws from the tower basin or from the condenser water return main and discharges to the basin or to the return main upstream of the chiller. For closed systems, the side-stream draws from the return main downstream of the air/dirt separator and discharges to the return main downstream of the side-stream loop.
+
+# Monitoring and Sampling
+
+## Sample Ports
+
+Sample ports shall be provided at locations that allow representative water sampling without disturbing equipment operation. For closed systems, the minimum sample-port set is one port on the supply main downstream of the air/dirt separator and one port on the return main upstream of the chiller or boiler; additional ports at each riser and at each major terminal-equipment branch allow zone-specific sampling to diagnose local chemistry issues. For open systems, sample ports shall be provided on the tower basin (representative of basin chemistry), on the condenser water supply to the chiller, and on the condenser water return from the chiller. Each port shall be a full-port ball valve in 1/4 in. or 1/2 in. line size, with a hose-bib outlet or a quick-connect fitting compatible with the service provider's sampling equipment, located at hand height (approximately 4 ft above the floor) in an accessible position with a permanent label identifying the system and the port location.
+
+```datasheet
+label: Sample Port Configuration
+type: select
+options:
+ - "Full-port ball valve, 1/4 in., with hose-bib outlet and cap"
+ - "Full-port ball valve, 1/2 in., with quick-connect outlet"
+ - "Sample cooler with isolation valve (steam and high-temperature systems)"
+default: "Full-port ball valve, 1/4 in., with hose-bib outlet and cap"
+```
+
+## Test Frequency
+
+The service provider shall test the systems at the frequency below, with results recorded in the service log. The frequencies shown are minimums; more frequent testing is required during start-up, after any chemistry change, after any major system upset (leak, equipment failure, repair), and during the first six months after a new system is commissioned.
+
+```datasheet
+label: Service Visit Frequency — Open Systems
+type: select
+options:
+ - "Weekly during cooling season, monthly during off-season"
+ - "Bi-weekly year-round"
+ - "Monthly year-round"
+ - "Per ASHRAE 188 Water Management Plan (minimum)"
+default: "Weekly during cooling season, monthly during off-season"
+```
+
+```datasheet
+label: Service Visit Frequency — Closed Systems
+type: select
+options:
+ - "Monthly"
+ - "Quarterly"
+ - "Bi-annually"
+default: "Quarterly"
+```
+
+```datasheet
+label: Service Visit Frequency — Steam Systems
+type: select
+options:
+ - "Weekly during heating season, monthly off-season"
+ - "Monthly year-round"
+ - "Per boiler operator schedule (daily by operator, service provider monthly)"
+default: "Monthly year-round"
+```
+
+## Corrosion Coupons
+
+Corrosion coupons are the gold-standard method of verifying that the inhibitor program is actually protecting the system metals. Coupons are weighed, pre-cleaned metal samples (typically carbon steel and copper, sometimes also admiralty brass or galvanized steel) installed in a coupon rack — a small parallel side-stream loop — exposed to system water at a controlled flow rate for a defined period (typically 90 days), then removed, cleaned, re-weighed, and analyzed for weight loss, pitting, deposit type, and surface appearance. Weight loss is reported as mils per year (mpy) of corrosion rate and compared against acceptance criteria. Acceptable corrosion rates per the AWT recommendations are typically below 1 mpy for carbon steel and below 0.2 mpy for copper in closed systems, and below 3 mpy carbon steel and below 0.2 mpy copper in open systems.
+
+```datasheet
+label: Corrosion Coupon Rack Installation
+type: radio
+options:
+ - "Required on every treated system, both closed and open"
+ - "Required on open systems and large closed systems; optional on small closed systems"
+ - "Not required (chemistry-only monitoring) — acceptable only for very small systems"
+default: "Required on every treated system, both closed and open"
+```
+
+```datasheet
+label: Coupon Metallurgy — Closed System
+type: checkbox
+options:
+ - "Carbon steel (primary structural metal)"
+ - "Copper (representative of coil tubes and small-bore piping)"
+ - "Admiralty brass (where condensers or specialty equipment use admiralty)"
+ - "Galvanized steel (where present, typically not used in closed systems)"
+default: "Carbon steel (primary structural metal)"
+```
+
+```datasheet
+label: Coupon Exposure Period
+type: select
+options:
+ - "90 days standard (industry norm)"
+ - "60 days (faster turnaround during start-up evaluation)"
+ - "180 days (extended exposure for slow-corroding closed systems)"
+ - "Continuous rotating coupon set (always one coupon at 30, 60, 90 days)"
+default: "90 days standard (industry norm)"
+```
+
+## Microbiological Monitoring
+
+Open systems shall be monitored for microbial activity. The minimum monitoring is dip-slide testing at each service visit for total aerobic bacteria (TAB), with action levels defined in the Water Management Plan. ATP testing per ASTM D4012 provides a rapid screening for total microbial load and is increasingly used as the primary in-field microbial test method because results are available in minutes rather than the 48-hour incubation required for dip slides. Routine Legionella sampling (culture method per ISO 11731 or qPCR molecular method) shall be performed at intervals specified in the Water Management Plan, with the typical interval being quarterly for non-healthcare facilities and monthly for healthcare and high-risk facilities; the local public health authority may require more frequent sampling.
+
+```datasheet
+label: Microbial Monitoring at Routine Service
+type: checkbox
+options:
+ - "Dip-slide for total aerobic bacteria (TAB)"
+ - "ATP test per ASTM D4012 (rapid screening)"
+ - "Sulfate-reducing bacteria (SRB) test (anaerobe sentinel)"
+ - "Nitrifying bacteria test (where nitrite chemistry is in use)"
+default: "Dip-slide for total aerobic bacteria (TAB)"
+```
+
+```datasheet
+label: Legionella Sampling Frequency — Open Cooling Towers
+type: select
+options:
+ - "Quarterly culture (ISO 11731) — typical commercial baseline"
+ - "Monthly culture — healthcare and high-risk facilities"
+ - "Quarterly culture plus quarterly qPCR — accelerated trend response"
+ - "Per local public health authority requirement (where stricter)"
+default: "Quarterly culture (ISO 11731) — typical commercial baseline"
+```
+
+A positive Legionella culture above the Water Management Plan's action threshold shall trigger the corrective-action procedure documented in the plan — typically including immediate hyperchlorination or hyperbromination of the affected system, intensified flushing, sample re-testing at 48 to 72 hours, and notification of building management and (depending on counts and jurisdiction) the local public health authority. Corrective-action procedures shall be developed by the design team and the service provider before the system is commissioned and shall be included in the closeout Water Management Plan binder.
+
+## BAS Integration of Treatment Data
+
+Treatment data — conductivity, ORP, pH, make-up flow, bleed flow, side-stream filter differential pressure, chemical-day-tank levels, alarm states — shall be reported to the building automation system through the controller's communication port. The points listed below shall be provided as a minimum. Coordinate point configuration with [[sync/building-automation-system]].
+
+```datasheet
+label: BAS Points from Water Treatment Controllers
+type: checkbox
+options:
+ - "Conductivity (4–20 mA or Modbus value)"
+ - "ORP (open systems, 4–20 mA or Modbus value)"
+ - "pH (where measured, 4–20 mA or Modbus value)"
+ - "Make-up water flow rate and cumulative make-up volume"
+ - "Bleed-off flow rate and cumulative bleed volume"
+ - "Side-stream filter differential pressure"
+ - "Chemical day-tank low-level alarm (each chemical)"
+ - "Bleed solenoid command and verification status"
+ - "Controller general fault / no-flow alarm"
+ - "Cycles of concentration (calculated, open systems)"
+default: "Conductivity (4–20 mA or Modbus value)"
+```
+
+# Service Contract
+
+## Scope of Routine Service
+
+The water treatment service contract shall provide for routine on-site service at the frequencies established above, with each visit including: a visual inspection of system conditions (sight glasses, sample-port samples, cooling tower basin condition, side-stream filter condition); a calibration check of conductivity, ORP, and pH probes; collection of water samples and field testing for the parameters required by the system; calibration check and dose adjustment of chemical feed pumps; visual inspection of corrosion coupons (in-place — coupons are removed for analysis on the longer interval); microbiological testing per the program; review of the controller's data log for any trend indicating an issue; written service report uploaded to the Owner's records, the service provider's records, and the BAS as a service log point.
+
+```datasheet
+label: Routine Service Visit Deliverable
+type: checkbox
+options:
+ - "Written service report with all field test results"
+ - "Photographs of system condition (tower basin, sample appearance, equipment condition)"
+ - "Probe calibration records"
+ - "Pump calibration records"
+ - "Chemistry trend chart vs. control range"
+ - "Recommendations for chemistry adjustment or system action"
+ - "Upload to Owner's records system within 24 hours"
+default: "Written service report with all field test results"
+```
+
+## After-Hours Response
+
+The service contract shall include a defined after-hours response commitment for emergency situations — significant chemistry excursion, suspected biological event, chemical spill, feed equipment failure during cooling-season operation. The standard commitment is on-site response within 4 hours during the cooling season and within 24 hours otherwise; healthcare facilities and other high-risk facilities require shorter response intervals.
+
+```datasheet
+label: After-Hours Response Commitment
+type: select
+options:
+ - "On-site within 4 hours, cooling season; 24 hours otherwise (standard commercial)"
+ - "On-site within 2 hours, year-round (healthcare and high-risk)"
+ - "Phone support within 1 hour; on-site within 8 hours (small projects)"
+default: "On-site within 4 hours, cooling season; 24 hours otherwise (standard commercial)"
+```
+
+## Annual Comprehensive Review
+
+In addition to routine service visits, the service contract shall include an annual comprehensive review for each system: a complete water analysis at an independent laboratory (parameters listed in the make-up water analysis section, plus the inhibitor concentrations and microbial counts for the system in question); a corrosion coupon analysis; a review of the year's trend data; a re-evaluation of the chemistry program against the year's experience; a written annual report with recommendations for the upcoming year; an in-person review meeting with the Owner's facility staff. The annual review is the formal touch-point at which the program is recalibrated against actual experience and at which the Owner has the opportunity to direct any change in priorities or scope.
+
+# Documentation — Water Management Plan (ASHRAE 188)
+
+## Applicability
+
+Where the project includes any open cooling tower, evaporative condenser, decorative fountain, or other open recirculating water system, ASHRAE Standard 188 requires the Owner to establish and maintain a Water Management Plan for the building. The plan is a written document — typically a binder, increasingly supplemented by a digital records system — that identifies the building's water systems within scope, describes the control measures (treatment programs, design features, operational practices) for each system, sets control limits for the parameters that determine effectiveness of the control measures, defines a monitoring schedule, defines corrective-action procedures when control limits are exceeded, defines communication and documentation procedures, and names the people responsible for the program.
+
+The Engineer of Record, the water treatment service provider, and the Owner's facility staff each contribute to the Water Management Plan. The water treatment program described in this standard provides the control measures, control limits, monitoring schedule, and corrective-action procedures for the open systems under treatment. Other building water systems within ASHRAE 188 scope — domestic hot water, decorative fountains, humidifiers, certain medical equipment — have their own plan sections developed under the respective project scope.
+
+## Plan Content — Treatment-Related Sections
+
+The treatment-related sections of the Water Management Plan shall include the following at minimum.
+
+- System descriptions for each open recirculating system: equipment summary, recirculation flow, drift loss specification, make-up source, normal cycles of concentration, normal operating temperature range, occupancy and use of the surrounding building areas.
+- Control measures for each system: the chemistry program (inhibitor, biocide, scale inhibitor), the conductivity- and ORP-based control configuration, the side-stream filtration, the drift eliminators, the equipment shutdown and re-start procedures, and the seasonal lay-up procedure.
+- Control limits for each measured parameter: the upper and lower bounds within which the parameter must be maintained for the control measure to remain effective.
+- Monitoring procedures: the testing performed at each service visit, the testing frequency, the personnel performing each test, the records kept.
+- Corrective-action procedures: the specific steps to be taken when each control limit is exceeded, the personnel responsible for each step, the timing of each step, the notification procedure, the re-monitoring procedure to verify resolution.
+- Verification procedures: how the program's effectiveness is confirmed — corrosion coupon analysis, microbial trending, equipment condition inspection at scheduled intervals.
+- Documentation procedures: what records are kept, where they are kept, how long they are retained, who has access.
+- Roles and responsibilities: named individuals or positions responsible for each aspect of the program, including the Owner's representative, the operating engineer, the water treatment service provider, and the Owner's risk management or infection control representative where applicable.
+
+```datasheet
+label: Water Management Plan Format
+type: select
+options:
+ - "Printed binder maintained on-site, with digital backup"
+ - "Digital records system with controlled access, printed quick-reference posted at mechanical rooms"
+ - "Combined — full binder plus digital data system integrated with BAS"
+default: "Combined — full binder plus digital data system integrated with BAS"
+```
+
+```datasheet
+label: Water Management Plan Annual Review
+type: radio
+options:
+ - "Required — formal annual review and update by water management team"
+ - "Required — annual review plus event-driven review after any significant change"
+default: "Required — annual review plus event-driven review after any significant change"
+```
+
+## Plan Maintenance and Audit
+
+The Water Management Plan is a living document. It shall be reviewed and updated at least annually, and after any of the following: change in chemistry program, change in service provider, change in building occupancy or operating hours that affect water system use, addition or removal of equipment, corrective-action event that revealed a procedural gap, change in applicable regulation. The Owner shall maintain records demonstrating that the plan has been followed — service visit reports, chemistry results, corrosion coupon results, microbiological results, training records for the operating staff — for the retention period specified in the plan, typically a minimum of five years.
+
+External audit of the Water Management Plan — by a third-party auditor, by the local public health authority, by the Owner's insurance carrier, or by a regulatory body in response to a Legionella case — relies on these records being available, organized, and complete. The closeout submittals required by this standard establish the plan; the service contract maintains it; the Owner's facility staff own it.
+
+# Pipe and Equipment Identification
+
+All chemical feed lines, sample-port lines, and treated-water sample piping shall be labeled with the chemical name, the direction of flow, and any hazard warnings appropriate to the contents in accordance with ASME A13.1 and OSHA 29 CFR 1910.1200. Labels shall be permanent (engraved, adhesive vinyl, or wraparound printed sleeves) and shall be replaced when faded or damaged. Chemical day tanks and bulk tanks shall bear the chemical name, the SDS reference number, the maximum capacity, and a tank identification number consistent with the controller's chemical-feed pump number. Sample ports shall be labeled with the system and location (for example, "CHW Return Sample, Riser 3, Floor 4 Return Main"). The intent is that any service provider new to the site can identify each connection unambiguously and that an emergency responder can identify each chemical without requiring access to the SDS binder.
+
+```datasheet
+label: Chemical Feed Line Labeling
+type: radio
+options:
+ - "Permanent adhesive labels per ASME A13.1 at intervals not exceeding 25 ft and at each end"
+ - "Wraparound printed sleeves at each end, fittings, and valve"
+ - "Both — permanent labels plus printed sleeves at fittings"
+default: "Both — permanent labels plus printed sleeves at fittings"
+```
+
+# System Lay-Up and Decommissioning
+
+## Seasonal Lay-Up
+
+Systems that are taken out of service for a season — for example, a chilled water system in a heating-only winter period, or a cooling tower during cold months — shall be laid up in a manner that protects the metal surfaces during the off-season. Lay-up methods are wet (system kept full of treated water with inhibitor concentration boosted, typically with a slow recirculation maintained or with periodic circulation, ideally with nitrogen blanketing where practical) and dry (system drained, blown dry with compressed air, sealed against air ingress, sometimes with desiccant cartridges in the equipment). Wet lay-up is generally preferred for closed systems because the protective inhibitor film is maintained; dry lay-up is generally preferred for outdoor cooling towers in freezing climates and for any system where there is significant risk of freeze damage.
+
+```datasheet
+label: Seasonal Lay-Up Method — Cooling Tower (Cold-Climate Winter)
+type: select
+options:
+ - "Dry lay-up — drain, blow dry, seal basin and piping; restart procedure includes refill, biocide pre-treatment, chemistry charge"
+ - "Wet lay-up — basin heater on, recirculation continuous, inhibitor and biocide maintained"
+ - "Partial dry — basin and fill drained, tower piping drained to lowest point, mechanical room piping kept warm"
+default: "Dry lay-up — drain, blow dry, seal basin and piping; restart procedure includes refill, biocide pre-treatment, chemistry charge"
+```
+
+```datasheet
+label: Seasonal Lay-Up Method — Chilled Water System (Winter)
+type: select
+options:
+ - "Wet lay-up with elevated inhibitor concentration (1.5× operating level)"
+ - "Wet lay-up with nitrogen blanketing of expansion tank"
+ - "Continuous pump circulation 1 hour per week minimum"
+ - "Drained — only where the system has glycol protection or freeze risk drives drain"
+default: "Wet lay-up with elevated inhibitor concentration (1.5× operating level)"
+```
+
+## Restart from Lay-Up
+
+When a system is returned to service from lay-up, the program shall confirm that the protective chemistry is intact (wet lay-up) or that the system has been properly recommissioned (dry lay-up — repeated flush, biocide pre-treatment for open systems, re-passivation as needed for steel systems that have been dry for more than a few weeks). The restart procedure shall be documented in the Water Management Plan or in the service contract and shall be executed by qualified personnel.
+
+## End-of-Life Decommissioning
+
+When a system is decommissioned at end of life, the treated water shall be drained and disposed of in accordance with applicable environmental regulations. Treated water typically contains corrosion inhibitor, biocide residue, and dissolved metals (iron, copper) at concentrations that may exceed sewer discharge limits, particularly for open systems with concentrated chemistry. The service provider shall characterize the drained water for parameters of concern and arrange compliant disposal — typically sanitary sewer with prior coordination, or off-site disposal as regulated industrial waste for chemistry that cannot be discharged to sewer.
+
+# Coordination with Other Standards
+
+The treatment program established by this standard depends on the physical systems built per [[sync/hydronic-piping]] and [[sync/hvac-pumps]]. The cleanliness of the system at start-up determines whether the chemistry can establish effective control; the velocity profile of the system determines whether side-stream filtration reaches all zones; the placement of sample ports and chemical-feed connections affects whether the program can be operated and monitored without disassembly. The Engineer shall coordinate the treatment design with the piping and pump design early — at the schematic phase — so that sample-port and feed-connection locations are integrated with the piping layout rather than added afterward as field modifications. The cooling coils in [[sync/air-handling-units]] are direct beneficiaries of the chilled water treatment program, and the chemistry shall be confirmed compatible with the coil construction (copper tube, aluminum fin where present, gasketed or brazed headers). The chemical-feed controllers and the BAS integration described here interface with the building automation system per [[sync/building-automation-system]]; the controller's communication protocol, point list, alarm priority, and trend logging configuration are agreed at the BAS submittal stage.