+---
+title: Evaporative Coolers
+category: Mechanical / Air Distribution
+toc_depth: 3
+description: >
+ When to use: Factory-assembled evaporative air coolers — direct, indirect, and
+ two-stage (indirect/direct) — serving as primary or supplemental cooling in dry
+ climates (outdoor design wet-bulb at or below 68°F / 20°C) for commercial,
+ institutional, light-industrial, warehouse, and agricultural facilities. Covers
+ rooftop, ground, and wall-mounted packaged units, central-station evaporative
+ modules, and integral evaporative pre-cooling sections, including capacity,
+ casing and media materials, water distribution, bleed-off and water management,
+ controls integration, efficiency, and field commissioning, for new construction
+ and retrofit where refrigerant cooling is absent or used only as backup.
+ Not intended for: packaged rooftop units with integral DX cooling (see
+ [[sync/packaged-rooftop-units]]); split-system air conditioners and heat pumps
+ (see [[sync/split-system-air-conditioners]]); energy-recovery ventilators
+ without evaporative saturation (see [[sync/energy-recovery-ventilators]]);
+ dedicated outdoor-air systems unless an in-scope evaporative pre-cooling section
+ is incorporated (see [[sync/dedicated-outdoor-air-systems]]); VAV terminals
+ downstream of the cooler (see [[sync/variable-air-volume-terminals]]); HVAC
+ ductwork beyond the discharge connection (see [[sync/hvac-ductwork]]); makeup-air
+ units whose primary function is direct-fired heating or DX cooling (see
+ [[sync/makeup-air-units]]); standalone HVAC fans (see [[sync/hvac-fans]]);
+ cooling towers rejecting condenser heat (see [[sync/cooling-towers]]); closed-loop
+ hydronic water treatment (see [[sync/hvac-water-treatment]]); condensate and
+ overflow drainage piping (see [[sync/condensate-drainage-piping]]); and testing,
+ adjusting, and balancing of supply airflow (see [[sync/testing-adjusting-and-balancing]]).
+---
+
+# Scope {toc}
+
+## This Standard covers factory-assembled evaporative air coolers — direct, indirect, and two-stage indirect/direct — furnished as packaged units or as central-station modules within an air handler. {note}
+
+## Evaporative cooling exchanges sensible heat for latent heat: water evaporated into an air stream lowers its dry-bulb temperature toward the wet-bulb temperature. Because the process is driven by the wet-bulb depression of the entering air, the achievable cooling — and therefore the entire premise of this equipment — depends on the local outdoor design wet-bulb temperature, not the dry-bulb temperature alone. {note}
+
+## The three evaporative configurations differ fundamentally in whether they add moisture to the supply air, and selecting the wrong type is the most consequential error in this scope. {note}
+
+## A direct evaporative cooler passes the supply air directly through wetted media, cooling and humidifying it in one step. An indirect evaporative cooler cools the supply air through a heat exchanger whose opposite (scavenger) side is evaporatively cooled, so the supply air is cooled sensibly with no moisture added. A two-stage unit places an indirect stage ahead of a direct stage, pre-cooling the air sensibly before the direct stage drives it closer to the lower wet-bulb, yielding the deepest temperature drop and the lowest supply humidity for a given final temperature. {note}
+
+## Equipment in this Standard is intended for climates with an outdoor design wet-bulb temperature at or below 68°F (20°C); above that threshold, two-stage or supplemental refrigerant cooling is required for acceptable performance. {note}
+
+## Evaporative cooling cannot lower air below the entering wet-bulb temperature, and effectiveness degrades as ambient humidity rises. In humid climates a direct cooler raises indoor relative humidity without delivering meaningful sensible cooling, producing comfort complaints and condensation. Confirm the outdoor design wet-bulb against ASHRAE climatic design data before specifying this equipment. {note}
+
+## Excluded equipment is governed by the standard that owns it. {note}
+
+## The following are outside this Standard: {note}
+- Packaged rooftop units with integral DX refrigerant cooling — see [[sync/packaged-rooftop-units]].
+- Split-system air conditioners and heat pumps — see [[sync/split-system-air-conditioners]].
+- Energy-recovery ventilators providing sensible or total-enthalpy exchange without evaporative saturation — see [[sync/energy-recovery-ventilators]].
+- Dedicated outdoor-air systems, unless they incorporate an in-scope evaporative pre-cooling section — see [[sync/dedicated-outdoor-air-systems]].
+- Variable air volume terminal units downstream of the cooler — see [[sync/variable-air-volume-terminals]].
+- HVAC ductwork and air distribution beyond the cooler discharge connection — see [[sync/hvac-ductwork]] and [[sync/hvac-air-distribution-devices]].
+- Makeup-air units whose primary function is direct-fired heating or DX cooling — see [[sync/makeup-air-units]].
+- HVAC fans specified as standalone components — see [[sync/hvac-fans]].
+- Cooling towers rejecting condenser heat in refrigeration or chilled-water plants — see [[sync/cooling-towers]].
+- Closed-loop hydronic water treatment — see [[sync/hvac-water-treatment]].
+- Condensate and overflow drainage piping — see [[sync/condensate-drainage-piping]].
+- Supply airflow testing, adjusting, and balancing — see [[sync/testing-adjusting-and-balancing]].
+
+## The Contractor shall provide a complete and operational evaporative cooling system, including the cooler, water supply and distribution, bleed-off and drainage connections, controls, and field commissioning.
+
+## Where this Standard conflicts with a more stringent code or authority-having-jurisdiction requirement, the more stringent requirement shall govern.
+
+# Referenced Standards {toc}
+
+## Equipment, materials, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited.
+
+## Where referenced standards conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
+
+| Standard | Title |
+|----------|-------|
+| ANSI/ASHRAE 133 | Method of Testing Direct Evaporative Air Coolers |
+| ANSI/ASHRAE 143 | Method of Testing for Rating Indirect Evaporative Coolers |
+| ANSI/ASHRAE 62.1-2022 | Ventilation and Acceptable Indoor Air Quality |
+| ANSI/ASHRAE/IES 90.1 | Energy Standard for Sites and Buildings Except Low-Rise Residential Buildings |
+| ANSI/ASHRAE 188-2021 | Legionellosis: Risk Management for Building Water Systems |
+| ANSI/ASHRAE 55 | Thermal Environmental Conditions for Human Occupancy |
+| UL 507 | Electric Fans |
+| UL 900 | Air Filter Units |
+| NFPA 70 | National Electrical Code (Article 440) |
+| ANSI/AMCA 210 / ASHRAE 51 | Laboratory Methods of Testing Fans for Certified Aerodynamic Performance Rating |
+| NSF/ANSI 61 | Drinking Water System Components — Health Effects |
+| SMACNA | HVAC Duct Construction Standards — Metal and Flexible |
+
+# Submittals {toc}
+
+## Action Submittals {toc}
+
+### The Contractor shall submit the following action submittals for review before fabrication or ordering:
+- Product data for each evaporative cooler, including capacity, configuration, and accessories.
+- Rated performance data: airflow, saturation effectiveness or indirect effectiveness, supply air temperature drop at design conditions, and external static pressure, with the ASHRAE 133 or ASHRAE 143 test basis identified.
+- Fan performance curves with the selected operating point, certified per AMCA 210 / ASHRAE 51.
+- Water consumption and bleed-off rate at design airflow.
+- Casing, media, and water-contact material designations with corrosion-resistance basis.
+- Electrical data: voltage, phase, motor horsepower, full-load amps, minimum circuit ampacity, and maximum overcurrent protection.
+- Dimensioned drawings showing operating weight, full-sump weight, discharge orientation, and required clearances.
+- Wiring and controls interface diagram, including BAS points list where integration is specified.
+- Sound power or sound pressure data by octave band.
+
+```datasheet
+label: Action submittals required
+type: checkbox
+options:
+ - Product data for each cooler
+ - Rated performance data (ASHRAE 133 / 143 basis)
+ - Fan performance curves (AMCA 210)
+ - Water consumption and bleed-off rate
+ - Casing, media, and water-contact materials
+ - Electrical data and circuit sizing
+ - Dimensioned drawings with operating and full-sump weights
+ - Controls interface and BAS points diagram
+ - Sound data by octave band
+default: []
+```
+
+## Closeout Submittals {toc}
+
+### The Contractor shall submit the following closeout submittals before Substantial Completion:
+- Operation and maintenance manuals, including media replacement and water-treatment procedures.
+- The Water Management Plan prepared in accordance with ASHRAE 188-2021.
+- Field commissioning and startup reports, including measured airflow, effectiveness, and bleed-off rate.
+- Manufacturer warranty documentation.
+- Record drawings reflecting installed configuration and connections.
+
+```datasheet
+label: Closeout submittals required
+type: checkbox
+options:
+ - Operation and maintenance manuals
+ - ASHRAE 188 Water Management Plan
+ - Field commissioning and startup reports
+ - Warranty documentation
+ - Record drawings
+default: []
+```
+
+## Informational Submittals {toc}
+
+### The Contractor shall submit the following informational submittals:
+- Third-party or AHRI-certified effectiveness ratings demonstrating compliance with the specified test standard.
+- UL 900 listing documentation for evaporative media.
+- NSF/ANSI 61 certification for water-wetted components connected to the potable supply.
+- Structural loading data for coordination with the structural engineer.
+
+```datasheet
+label: Informational submittals required
+type: checkbox
+options:
+ - Certified effectiveness ratings (ASHRAE 133 / 143)
+ - UL 900 media listing
+ - NSF/ANSI 61 wetted-component certification
+ - Structural loading data
+default: []
+```
+
+# Quality Assurance {toc}
+
+## Rated performance shall be established by test in accordance with ANSI/ASHRAE 133 for direct evaporative coolers and ANSI/ASHRAE 143 for indirect evaporative coolers.
+
+## Claimed saturation effectiveness shall be supported by third-party or AHRI-certified test data.
+
+## Manufacturer's uncertified ratings shall not be the basis of design.
+
+## Saturation effectiveness is the single number that determines delivered cooling, yet it is frequently overstated in unverified literature. Requiring a recognized test basis protects the design calculation and gives the Engineer of Record a defensible performance floor. {note}
+
+## The supply fan and motor assembly shall be listed to UL 507.
+
+## Evaporative media shall be listed to UL 900 Class II.
+
+## Class I combustible media shall not be used in occupied buildings without a fire suppression system.
+
+## UL 900 distinguishes combustibility classes. Class I media will support flame propagation and is prohibited in occupied spaces absent suppression; Class II media is the appropriate listing for general building use and is called out explicitly to prevent substitution. {note}
+
+## Electrical components and circuiting shall comply with NFPA 70, Article 440, for motor branch-circuit sizing, disconnect, and overcurrent protection.
+
+## Water-wetted components connected to a potable supply — sumps, pads, and distribution headers — shall comply with NSF/ANSI 61.
+
+# Environmental and Service Conditions {toc}
+
+## Evaporative coolers shall be selected for the project's outdoor design dry-bulb and coincident design wet-bulb temperatures taken from ASHRAE climatic design data.
+
+## Direct evaporative coolers shall not be applied where the outdoor design wet-bulb temperature exceeds 68°F (20°C) unless preceded by an indirect stage or supplemented by refrigerant cooling.
+
+## Above roughly 68°F wet-bulb the achievable dry-bulb drop collapses while the moisture added by a direct stage pushes indoor humidity into the complaint range. The two-stage configuration extends the useful climate envelope by pre-cooling sensibly, and supplemental DX covers the remaining hours. {note}
+
+## Supply air conditions delivered to occupied spaces shall remain within the comfort envelope of ANSI/ASHRAE 55.
+
+## For direct evaporative systems serving occupied spaces, the design shall limit indoor relative humidity to 60% or below per ANSI/ASHRAE 62.1.
+
+## Direct evaporation raises supply humidity. In marginal climates this can drive indoor relative humidity above 60%, the threshold above which mold growth and surface condensation become likely. Indirect or two-stage configurations sidestep this constraint because they add no moisture to the supply stream. {note}
+
+## Systems introducing 100% outdoor air shall meet the minimum outdoor-air ventilation rates of ANSI/ASHRAE 62.1-2022 for the served occupancy.
+
+```datasheet
+label: Outdoor design wet-bulb temperature
+type: range
+unit: °F
+min: 55
+max: 78
+step: 1
+drawing_ref: true
+```
+
+```datasheet
+label: Outdoor design dry-bulb temperature
+type: range
+unit: °F
+min: 90
+max: 115
+step: 1
+drawing_ref: true
+```
+
+```datasheet
+label: Evaporative cooling type
+type: radio
+options:
+ - Direct evaporative
+ - Indirect evaporative
+ - Two-stage indirect/direct
+default: Direct evaporative
+```
+
+```datasheet
+label: Application climate basis
+type: select
+options:
+ - Arid (design WB ≤ 60°F)
+ - Semi-arid (design WB 60-68°F)
+ - Marginal (design WB > 68°F, two-stage required)
+default: Semi-arid (design WB 60-68°F)
+```
+
+# Capacity and Performance {toc}
+
+## Each evaporative cooler shall deliver the scheduled supply airflow against the scheduled external static pressure.
+
+## Airflow for evaporative systems is typically sized for high air-change rates — commonly 20 to 40 air changes per hour — because the supply air is delivered at a smaller temperature differential than refrigerant systems, so more air volume is required for equivalent sensible cooling. Commercial rooftop units generally fall between 5,000 and 20,000 CFM, with industrial and warehouse units reaching 60,000 CFM. {note}
+
+## Direct evaporative coolers shall achieve the scheduled saturation effectiveness at design airflow when tested per ANSI/ASHRAE 133.
+
+## Saturation effectiveness is the fraction of the wet-bulb depression that the cooler actually delivers. Rigid corrugated media units commonly achieve 85% to 90%; thin aspen-pad units fall lower. The default below reflects the common commercial rigid-media case. {note}
+
+## Indirect evaporative coolers shall achieve the scheduled effectiveness, expressed as a fraction of the entering wet-bulb depression, when tested per ANSI/ASHRAE 143.
+
+## Two-stage units shall be selected to deliver the scheduled supply air temperature, typically 10°F to 25°F below outdoor dry-bulb in arid climates at the design condition.
+
+```datasheet
+label: Design supply airflow per unit
+type: range
+unit: CFM
+min: 3000
+max: 60000
+step: 500
+default: 12000
+```
+
+```datasheet
+label: External static pressure
+type: range
+unit: in. w.g.
+min: 0.10
+max: 1.50
+step: 0.05
+default: 0.50
+```
+
+```datasheet
+label: Direct-stage saturation effectiveness (minimum)
+type: range
+unit: '%'
+min: 75
+max: 95
+step: 1
+default: 88
+```
+
+```datasheet
+label: Indirect-stage effectiveness (minimum)
+type: range
+unit: '%'
+min: 55
+max: 80
+step: 1
+default: 70
+```
+
+```datasheet
+label: Design supply air temperature drop below outdoor dry-bulb
+type: range
+unit: °F
+min: 8
+max: 28
+step: 1
+default: 18
+```
+
+# Casing and Cabinet Construction {toc}
+
+## The cabinet shall be of weather-resistant construction suitable for the installed exposure and shall not deflect or distort under operating and wind loads.
+
+## Water-contact surfaces shall be corrosion-resistant for the service water chemistry and the installed environment. {note}
+
+## The sump, distribution headers, and wetted casing surfaces are continuously exposed to mineral-laden recirculating water and intermittent wet/dry cycling, which is far more aggressive than the dry air-side surfaces. Stainless steel or polymer water-contact construction is warranted in coastal, high-TDS, or corrosive-process environments; galvanized or aluminized steel is acceptable for benign inland water and air. {note}
+
+## The sump shall drain completely with no standing pockets and shall include a manual drain connection.
+
+## Access panels shall be provided for media, sump, distribution header, and fan service without removing ductwork or adjacent equipment.
+
+## Insulated casing sections subject to condensation on the cold supply side shall be provided where required to prevent surface condensation; coordinate exterior duct insulation with [[sync/mechanical-insulation]].
+
+```datasheet
+label: Casing and structural material
+type: select
+options:
+ - Galvanized steel (G90)
+ - Aluminized steel
+ - 304 stainless steel
+ - Polymer / composite
+default: Galvanized steel (G90)
+```
+
+```datasheet
+label: Water-contact (sump and header) material
+type: select
+options:
+ - Galvanized steel
+ - Aluminized steel
+ - 304 stainless steel
+ - Polymer
+default: 304 stainless steel
+```
+
+```datasheet
+label: Mounting configuration
+type: radio
+options:
+ - Rooftop (curb-mounted)
+ - Ground / slab-mounted
+ - Wall-mounted
+ - Central-station module (within AHU)
+default: Rooftop (curb-mounted)
+```
+
+```datasheet
+label: Discharge configuration
+type: radio
+options:
+ - Top discharge
+ - Down discharge
+ - Horizontal / side discharge
+default: Down discharge
+```
+
+# Evaporative Media {toc}
+
+## Media shall be a rigid, self-supporting evaporative material that maintains its shape and saturation characteristics over the service life and resists sagging, channeling, and biological fouling. {note}
+
+## Media is the heart of the cooler: its depth and surface geometry set both the saturation effectiveness and the air-side pressure drop. Rigid cellulose and corrugated PVC media hold their geometry and wet uniformly; loose aspen pads sag, channel, and degrade quickly. Thicker media raises effectiveness at the cost of pressure drop — 4 in. media yields roughly 80% effectiveness, 8 in. roughly 90%, and 12 in. media is reserved for high-effectiveness industrial duty. {note}
+
+## Media shall be listed to UL 900 Class II.
+
+## Media shall be supported and oriented so that the full face wets uniformly and distribution water cannot bypass the media unevaporated.
+
+## Media shall be replaceable as a field operation through the provided access without cutting or destructive removal of adjacent components.
+
+```datasheet
+label: Media type
+type: select
+options:
+ - Rigid cellulose (corrugated)
+ - Corrugated PVC / plastic
+ - Rigid fiberglass
+default: Rigid cellulose (corrugated)
+```
+
+```datasheet
+label: Media thickness
+type: radio
+options:
+ - 4 in.
+ - 8 in.
+ - 12 in.
+default: 8 in.
+```
+
+# Water Distribution and Sump {toc}
+
+## The water distribution system shall wet the entire media face uniformly at the design recirculation rate. {note}
+
+## Two arrangements are common: top-feed gravity distribution, where water is metered across the top of the media and trickles down, and recirculating pump-and-header systems, where a sump pump lifts water to a perforated header. Pump-and-header systems give more uniform wetting and are standard for larger commercial units; gravity systems are simpler and suit small units. {note}
+
+## The sump shall provide a water reserve of at least three minutes at the full design evaporation rate to ride through makeup-supply interruptions without running the media dry.
+
+## A float-controlled automatic makeup water fill valve with an integral or upstream pressure regulator shall maintain sump level. {note}
+
+## Omitting the regulator or undersizing the makeup line is a frequent failure: the unit starves, media dries and degrades, and the recirculation pump runs dry and burns out. The regulator stabilizes fill against supply-pressure swings and protects the float valve. {note}
+
+## A sump overflow connection shall be piped to drain to prevent flooding on float-valve failure.
+
+## Coordinate overflow and bleed-off drain routing with [[sync/condensate-drainage-piping]]. {note}
+
+## Water supplied to the cooler shall be of potable quality.
+
+```datasheet
+label: Water distribution arrangement
+type: radio
+options:
+ - Top-feed gravity distribution
+ - Recirculating pump-and-header
+default: Recirculating pump-and-header
+```
+
+```datasheet
+label: Sump capacity
+type: range
+unit: gal
+min: 3
+max: 30
+step: 1
+default: 12
+```
+
+```datasheet
+label: Makeup water connection size
+type: select
+options:
+ - 3/8 in.
+ - 1/2 in.
+ - 3/4 in.
+ - 1 in.
+default: 1/2 in.
+```
+
+# Water Management and Treatment {toc}
+
+## A Water Management Plan complying with ANSI/ASHRAE 188-2021 shall be prepared for the evaporative cooler water system. {note}
+
+## Direct evaporative coolers aerosolize recirculating water and therefore fall within the Legionella risk scope of ASHRAE 188. The Water Management Plan documents control measures, bleed-off and disinfection protocols, and monitoring, and is a non-negotiable deliverable for commercial installations. This obligation is independent of the cooling-tower water program in [[sync/hvac-water-treatment]] and [[sync/cooling-towers]], which serves a different purpose and risk profile. {note}
+
+## A continuous bleed-off (blowdown) system shall be provided to limit dissolved-solids accumulation in the recirculating water. {note}
+
+## As water evaporates it leaves its minerals behind, concentrating dissolved solids in the sump. Without bleed-off, scale builds on media and headers, effectiveness falls, and biofilm proliferates. Bleed-off ratios commonly run between 1:3 and 1:6 of the evaporated water; a practical floor is about 1 gallon per hour per 1,000 CFM, adjusted to hold total dissolved solids below roughly 2,000 ppm. {note}
+
+## The system shall maintain recirculating-water total dissolved solids at or below 2,000 ppm, or the manufacturer's lower limit, by adjusting the bleed-off rate.
+
+## Provision shall be made for biocide dosing of the recirculating water in accordance with the Water Management Plan.
+
+## The bleed-off shall discharge to an approved drain.
+
+## Bleed-off shall not be routed to the supply air stream.
+
+```datasheet
+label: Continuous bleed-off rate
+type: range
+unit: gal/h per 1000 CFM
+min: 0.5
+max: 4.0
+step: 0.5
+default: 1.0
+```
+
+```datasheet
+label: Maximum recirculating-water TDS
+type: range
+unit: ppm
+min: 1000
+max: 2500
+step: 100
+default: 2000
+```
+
+```datasheet
+label: Biocide dosing provision
+type: radio
+options:
+ - Manual dosing port
+ - Automatic metered dosing
+default: Manual dosing port
+```
+
+# Fan and Motor {toc}
+
+## The supply fan shall deliver the scheduled airflow at the scheduled external static pressure with performance certified per ANSI/AMCA 210 / ASHRAE 51. {note}
+
+## Fan power for commercial direct-drive units typically falls in the 1 to 3 hp range, with the full range from a fraction of a horsepower for small units to about 10 hp for large industrial coolers. Direct-drive fans eliminate belt maintenance; belt-drive fans allow speed adjustment by sheave change but introduce the most common maintenance failure mode. {note}
+
+## Where a belt-drive fan is provided, the Contractor shall commission belt tension at startup and furnish one spare belt set per unit. {note}
+
+## Belt slip is the leading cause of lost airflow in belt-driven coolers. Commissioning tension and stocking spares converts a recurring failure into a routine service item. {note}
+
+## Variable-speed fan operation, where specified, shall be provided by a variable-frequency drive sized for the motor and rated for the installed environment.
+
+## Motor electrical characteristics shall match the project power supply and be circuited per NFPA 70.
+
+```datasheet
+label: Fan drive arrangement
+type: radio
+options:
+ - Direct-drive
+ - Belt-drive
+default: Direct-drive
+```
+
+```datasheet
+label: Fan speed control
+type: radio
+options:
+ - Single-speed
+ - Two-speed
+ - Variable-speed (VFD)
+default: Single-speed
+```
+
+```datasheet
+label: Fan motor power
+type: range
+unit: hp
+min: 0.25
+max: 10
+step: 0.25
+default: 2
+```
+
+```datasheet
+label: Electrical supply
+type: select
+options:
+ - 120V / 1Φ / 60Hz
+ - 208-240V / 1Φ / 60Hz
+ - 208-240V / 3Φ / 60Hz
+ - 480V / 3Φ / 60Hz
+default: 208-240V / 3Φ / 60Hz
+```
+
+# Intake, Filtration, and Dampers {toc}
+
+## The air intake shall be provided with a weather louver and bird screen to exclude rain, debris, and pests.
+
+## Coordinate intake louvers with [[sync/louvers-and-dampers]]. {note}
+
+## A pre-filter shall be provided upstream of the media to protect it from airborne debris. {note}
+
+## A MERV-8 pre-filter is typical for commercial service: it captures the coarse dust that would otherwise foul and channel the media without imposing the pressure penalty of higher-efficiency filtration. Filtration efficiency selection should reflect the served occupancy and the air distribution devices downstream — see [[sync/hvac-air-distribution-devices]]. {note}
+
+## A discharge or relief damper shall be provided where required to isolate the unit when off and to prevent backdraft.
+
+```datasheet
+label: Pre-filter efficiency
+type: select
+options:
+ - MERV 8
+ - MERV 11
+ - MERV 13
+default: MERV 8
+```
+
+```datasheet
+label: Intake louver and bird screen
+type: checkbox
+options:
+ - Weather louver
+ - Insect / bird screen
+default:
+ - Weather louver
+ - Insect / bird screen
+```
+
+# Controls and Integration {toc}
+
+## The cooler shall be controlled to maintain the space or supply setpoint while sequencing the recirculation pump and supply fan to avoid running the fan over dry media or the pump without airflow. {note}
+
+## A proper sequence wets the media before or as the fan starts and continues a post-purge or drain cycle after shutdown. Running the fan over dry media wastes energy and delivers no cooling; running the pump with no airflow needlessly concentrates the sump. {note}
+
+## Where building automation integration is specified, the cooler controls shall expose monitoring and command points over a standard protocol and shall honor BAS occupancy schedules and demand-controlled ventilation; integrate with [[sync/building-automation-system]]. {note}
+
+## Stand-alone thermostatic control is common and acceptable for simple installations, but it leaves the cooler disconnected from occupancy schedules and ventilation demand. Specifying the integration scope explicitly prevents the cooler from being stranded outside the BAS. {note}
+
+## Stand-alone control, where specified, shall be by a thermostat and, for direct units, a humidistat high-limit that disables evaporation when indoor humidity reaches the setpoint.
+
+```datasheet
+label: Controls integration level
+type: radio
+options:
+ - Stand-alone thermostat / humidistat
+ - BAS hardwired points
+ - Full BACnet / Modbus integration
+default: BAS hardwired points
+```
+
+```datasheet
+label: Humidistat high-limit (direct units)
+type: range
+unit: '% RH'
+min: 50
+max: 65
+step: 1
+default: 60
+```
+
+# Energy and Ventilation Coordination {toc}
+
+## The system shall comply with the applicable efficiency, economizer, and ventilation provisions of ANSI/ASHRAE/IES 90.1 for the project. {note}
+
+## Evaporative cooling is itself an efficiency strategy and can serve as the economizer or as evaporative pre-cooling of packaged-equipment condenser air for an EER credit. The design must still satisfy 90.1's ventilation and economizer provisions for the served system. {note}
+
+## Building relief and exhaust openings shall be sized to pass the full supply airflow at a slight positive building pressure. {note}
+
+## Evaporative coolers move large outdoor-air volumes; if the building cannot relieve that air, pressure builds, airflow falls, and doors become hard to open. Relief area must be proportional to the high air-change supply rate — coordinate relief, exhaust, and TAB with [[sync/testing-adjusting-and-balancing]]. {note}
+
+## Discharge and inlet duct connections shall be made in accordance with the SMACNA HVAC Duct Construction Standards; see [[sync/hvac-ductwork]].
+
+```datasheet
+label: Evaporative system role
+type: radio
+options:
+ - Primary cooling
+ - Supplemental / pre-cooling to DX
+ - Economizer / ventilation cooling
+default: Primary cooling
+```
+
+# Winterization and Freeze Protection {toc}
+
+## In climates subject to freezing, the cooler shall include freeze protection appropriate to the exposure. {note}
+
+## Standing water left in the sump and distribution headers will freeze and crack the casing or sump pan. Two approaches are used: a drain-down sequence that empties the water system on shutdown for the season, which is sufficient for most applications, and electric heat trace on the sump and headers where the unit must remain wet through freezing periods. {note}
+
+## The freeze-protection sequence shall fully drain the sump, distribution headers, and supply piping when seasonal shutdown is initiated.
+
+## Where heat trace is provided, it shall be controlled by an ambient or pipe-mounted thermostat and circuited per NFPA 70.
+
+```datasheet
+label: Freeze protection method
+type: radio
+options:
+ - Seasonal drain-down only
+ - Drain-down with sump / header heat trace
+ - None (non-freezing climate)
+default: Seasonal drain-down only
+```
+
+# Structural Support and Mounting {toc}
+
+## Roof or structural support shall be designed for the cooler's full-sump operating weight, including the water charge. {note}
+
+## Evaporative coolers are heavier than comparably sized packaged DX units once the sump is filled, and the water charge is a sustained dead load, not an incidental one. Verify the operating weight against the structural design with the structural engineer of record before setting the unit. {note}
+
+## Rooftop units shall be set on a level, properly flashed curb sized to the unit and weatherproofed against the roof assembly.
+
+## Vibration isolation shall be provided as required to limit structure-borne noise transmission to occupied spaces.
+
+```datasheet
+label: Operating (full-sump) weight basis confirmed with structural engineer
+type: radio
+options:
+ - Confirmed
+ - Pending coordination
+default: Pending coordination
+```
+
+# Acoustics {toc}
+
+## The cooler shall not exceed the project's sound limit at the specified measurement location. {note}
+
+## Rooftop units commonly produce 65 to 80 dBA measured at 5 ft. Urban and noise-sensitive sites should specify a maximum NC level or a dBA limit at the property line rather than relying on the unit's free-field rating alone. {note}
+
+## Where a property-line or interior noise limit applies, the Contractor shall furnish sound data demonstrating compliance and provide attenuation as required to meet it.
+
+```datasheet
+label: Maximum sound pressure at 5 ft
+type: range
+unit: dBA
+min: 60
+max: 82
+step: 1
+default: 72
+```
+
+```datasheet
+label: Acoustic limit basis
+type: radio
+options:
+ - Manufacturer free-field rating only
+ - NC level at occupied space
+ - dBA limit at property line
+default: Manufacturer free-field rating only
+```
+
+# Testing {toc}
+
+## Each cooler shall be factory performance-verified to ANSI/ASHRAE 133 (direct) or ANSI/ASHRAE 143 (indirect) prior to shipment. {note}
+
+## Factory verification confirms the unit will meet its scheduled performance before it reaches the roof, where corrective measures are far costlier. The acceptance window below reflects standard rating tolerances. {note}
+
+## Factory-measured airflow shall be within ±5% of the rated value, and measured effectiveness shall be within 5 percentage points of the rated value.
+
+## At startup, the Contractor shall field-verify airflow, supply air temperature drop, bleed-off rate, makeup operation, and the control sequence, and shall record results in the commissioning report.
+
+## Supply airflow shall be balanced under [[sync/testing-adjusting-and-balancing]]; the cooler startup shall be completed and coordinated before final air balance.
+
+```datasheet
+label: Factory performance test basis
+type: radio
+options:
+ - ASHRAE 133 (direct)
+ - ASHRAE 143 (indirect)
+ - Both stages (two-stage unit)
+default: Both stages (two-stage unit)
+```
+
+```datasheet
+label: Field commissioning verifications
+type: checkbox
+options:
+ - Airflow
+ - Supply air temperature drop
+ - Bleed-off rate
+ - Makeup / float valve operation
+ - Control sequence
+default:
+ - Airflow
+ - Supply air temperature drop
+ - Bleed-off rate
+ - Makeup / float valve operation
+ - Control sequence
+```
+
+# Installation {toc}
+
+## The cooler shall be installed level, plumb, and in the orientation shown, with the discharge connected as indicated [[drawing: mechanical roof plan]].
+
+## Makeup water, bleed-off, overflow, and drain connections shall be made complete and leak-tested before startup.
+
+## Electrical service, disconnect, and controls wiring shall be completed and verified before energizing the fan and pump.
+
+## Required service clearances shall be maintained around all access panels for media, sump, header, and fan service.
+
+## Penetrations of the roof or wall assembly shall be flashed and sealed weathertight.
+
+# Delivery, Storage, and Handling {toc}
+
+## Units and media shall be delivered in the manufacturer's packaging and protected from weather, dust, and physical damage until installation.
+
+## Media shall be stored dry, flat, and supported to prevent crushing, sagging, or distortion of the corrugations.
+
+## Units shall be handled and rigged at the manufacturer's designated lifting points without distorting the casing or sump.
+
+# Warranty {toc}
+
+## The Contractor shall furnish the manufacturer's standard warranty against defects in materials and workmanship for the evaporative cooler.
+
+## The warranty shall separately address the casing and sump against corrosion perforation for the wetted-component service life. {note}
+
+## The water-wetted casing and sump corrode on a different timeline than the dry air-side cabinet, so the corrosion warranty is the meaningful coverage for this equipment. Calling it out separately prevents it from being absorbed into a shorter general parts warranty. {note}
+
+```datasheet
+label: Cabinet and sump corrosion warranty period
+type: range
+unit: years
+min: 1
+max: 10
+step: 1
+default: 5
+```
+
+```datasheet
+label: Fan and motor warranty period
+type: range
+unit: years
+min: 1
+max: 5
+step: 1
+default: 2
+```
+
+# Spare Parts {toc}
+
+## The Contractor shall furnish the following spare parts to the Owner at closeout:
+- One complete set of evaporative media per unit.
+- One spare belt set per belt-driven unit.
+- One spare float / makeup fill valve per unit.
+
+```datasheet
+label: Spare parts furnished
+type: checkbox
+options:
+ - One complete media set per unit
+ - One spare belt set per belt-driven unit
+ - One spare float / fill valve per unit
+default:
+ - One spare belt set per belt-driven unit
+ - One spare float / fill valve per unit
+```
+
+## --- {note}
+
+## *This SynC standard is independently authored from public consensus standards, building codes, and professional engineering knowledge. Licensed CC BY-SA.* {note}