Issue link: https://hi.iaq.net/i/248503
www.epa.gov/iaq/moisture Cooling Coils, Drain Pans, and Condensate Lines • Inspect coils, pans and condensate lines regularly for cleanliness and to ensure the drain is operating correctly. Clean or repair faulty drains as necessary. • Ensure that all traps have water in them. During times of the year when the HVAC system is not used, or when condensate formation is low, the trap can dry out, allowing sewer gases or other gases in the drainage system to be drawn into the HVAC unit and distributed through the building. Fill empty drain traps with water. • Closely inspect the ducts downstream from the cooling coil for mold growth or signs of condensation being blown off the coil. If mold is found growing on hard-surface ductwork (e.g., sheet metal) or closed-cell insulation, have the ductwork evaluated by a mold remediation specialist or a qualified duct cleaner. If mold is found growing on internal porous duct insulation, remove and replace the insulation because it cannot be effectively cleaned. Evaporative Cooling Equipment (Common in Dry Climates) • Inspect the evaporative pad media regularly for cleanliness, and even wetting, across the full face of the pad. Replace clogged media to ensure that supply air is not constricted and forced into highvelocity flow, which could pull water off the media and into the air stream and ductwork downstream. Similarly, make sure the water flow is even across the full face of the pad (for effective cooling) and not excessively high in any one spot, which could also result in water droplets being pulled off the media and into the air stream. • Ensure the overflow drain is operating correctly. Clean out or repair the drain lines as necessary to ensure that water does not collect in the sump and overflow the edge of the pan. (Overflows can otherwise leak into ductwork or into the building itself.) • Ensure that the media is not contacting standing water in the sump when the unit is not operating. The sump overflow adjustment must be low enough to prevent water from wicking back up into the media and supporting microbial growth. • Check the controls to ensure that the evaporative cooler does not operate when it is raining outdoors. Otherwise, the unit could overload the incoming air with humidity at a time when little evaporative cooling needs to be accomplished. Needlessly loading the indoor air with extra humidity can lead to excess moisture accumulation, even in dry climates. • Closely inspect the ducts downstream from the evaporative cooler coil for mold growth or signs of moisture being blown off the media. If mold is found growing on hard-surface ductwork (e.g., sheet metal) or closed-cell insulation, have the ductwork evaluated by a mold remediation specialist or a qualified duct cleaner. If mold is found growing on internal porous duct insulation, remove and replace the insulation because it cannot be effectively cleaned. Before the equipment is placed back in operation, locate and correct the problem that led to the carryover of water droplets which supported the mold growth. Air Filters • Do not rely solely on pressure drop warning equipment to determine the need to replace filters. Clogged filters can be sucked out of their frames and air may bypass the filter, resulting in no noticeable pressure drop. Visually inspect and replace air filters on a regular schedule. Turn unit fans off when changing filters to prevent contamination of the air. Be aware that some filters may need more frequent replacement than others because different areas of a facility may have different airborne particle burdens. • Record the date of the filter change in the maintenance manual and write the date of the change on the filter, if possible. Ducts and Supply Diffusers • Inspect ducts regularly, typically once a year or whenever modifications have been made to the ducts or the areas they serve. • Information about the potential benefits and possible problems of air duct cleaning is limited. The North American Air Duct Cleaners Association (NADCA) recommends duct cleaning if there is a significant build-up of particles, if the duct is contaminated with mold spores and trace mold growth, or if there is obvious mold growth. If mold is growing in ducts lined with porous insulation, the NADCA guidance recommends removing the insulation. When cleaning ductwork, follow the 2006 NADCA guidance Assessment, Cleaning and Restoration of HVAC Systems. 101