ASHRAE+62.1-2022+(1) - Page 013
Extracted Content
a. Access doors to permit cleaning of wetted surfaces shall be provided. b. Outdoor air ductwork or plenums shall pitch to drains designed in accordance with the requirements of
Section 5.7.
5.4.5 Bird Screens. Outdoor air intakes shall include a screening device designed to prevent penetration by a 0.5 in. (13 mm) diameter probe. The screening device material shall be corrosion resistant. The screening device shall be located, or other measures shall be taken, to prevent bird nesting within the outdoor air intake.
Informative Note: Any horizontal surface may be subject to bird nesting.
5.5 Particulate Matter Removal. Particulate matter filters or air cleaners having either
a. a MERV of not less than 8 where rated in accordance with ASHRAE Standard 52.2 or b. the minimum efficiency within ISO ePM10 where rated in accordance with ISO 16890
shall be provided upstream of all cooling coils or other devices with wetted surfaces through which air is supplied to an occupiable space. Exception to 5.5: Cooling coils that are designed, controlled, and operated to provide sensible cooling only.
5.6 Finned-Tube Coils and Heat Exchangers 5.6.1 Drain Pans. A drain pan, in accordance with Section 5.7, shall be provided beneath all dehumidifying cooling-coil assemblies and all condensate-producing heat exchangers.
5.6.2 Finned-Tube-Coil Selection for Cleaning. Individual finned-tube coils or multiple finned-tube coils in series without intervening access spaces of at least 18 in. (457 mm) shall be selected to result in no more than 0.75 in. of water (187 Pa) combined dry-coil pressure drop at 500 fpm (2.54 m/s) face velocity.
5.7 Drain Pans. Drain pans, including their outlets and seals, shall be designed and constructed in accordance with this section.
5.7.1 Drain Pan Slope. Pans intended to collect and drain liquid water shall be sloped at least 0.125 in./ft (10 mm/m) from the horizontal toward the drain outlet or shall be otherwise designed such that water drains freely from the pan whether the fan is ON or OFF.
5.7.2 Drain Outlet. The drain pan outlet shall be located at the lowest point(s) of the drain pan and shall be sized to preclude drain pan overflow under any normally expected operating condition.
5.7.3 Drain Seal. For configurations that result in negative static pressure at the drain pan relative to the drain outlet (such as a draw-through unit), the drain line shall include a P-trap or other sealing device designed to maintain a seal against ingestion of ambient air, while allowing complete drainage of the drain pan under any normally expected operating condition, whether the fan is ON or OFF.
5.7.4 Pan Size. The drain pan shall be located under the water-producing device. Drain pan width shall be sized to collect water droplets across the entire width of the water-producing device or assembly. For horizontal airflow configurations, the drain pan length shall begin at the leading face or edge of the water-producing device or assembly and extend downstream from the leaving face or edge to a distance of either
a. one half of the installed vertical dimension of the water-producing device or assembly or b. as necessary to limit water droplet carryover beyond the drain pan to 0.0044 oz/ft [2] (1.5 mL/m [2] ) of face
area per hour under peak sensible and peak dew-point design conditions, accounting for both latent load and coil face velocity.
5.8 Humidifiers and Water Spray Systems. Steam and direct-evaporative humidifiers, air washers, directevaporative coolers, and other water spray systems shall be designed in accordance with this section.
5.8.1 Water Quality. Water purity shall meet or exceed potable water standards at the point where it enters the ventilation system, space, or water vapor generator. Water vapor generated shall contain no chemical additives other than those chemicals in a potable water system.
Exceptions to 5.8.1:
- Water spray systems that use chemical additives that meet NSF/ANSI Standard 60.
- Boiler water additives that meet the requirements of 21 CFR 173.310 and include automated dosing devices.
5.8.2 Obstructions. Air cleaners or ductwork obstructions, such as turning vanes, volume dampers, and duct offsets greater than 15 degrees, that are installed downstream of humidifiers or water spray systems shall be located a distance equal to or greater than the absorption distance recommended by the humidifier or water spray system manufacturer.
Exception 5.8.2: Equipment such as eliminators, coils, or evaporative media shall be permitted to be
located within the absorption distance recommended by the manufacturer, provided a drain pan
ANSI/ASHRAE Standard 62.1-2022 11