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EPA Moisture Control Guide 2013

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www.epa.gov/iaq/moisture • Inspect ducts for physical damage. Look for crushed or disconnected ducts. Reconnect, repair or replace as necessary. unit and be distributed to the occupied areas of the building. • Periodically inspect buildings that have return air plenums for water-stained ceiling tiles, which may indicate mold growth. If mold growth is found or suspected, consult a qualified professional to determine the extent of the problem and remediation requirements. • Inspect all accessible duct seams and joints for leaks and seal all leaks with appropriate materials. Seal duct leaks with mastic, metal-backed tape or aerosol sealant. Duct tape should not be used because it dries out quickly and fails to hold and because it cannot withstand high temperatures. All sealing materials must comply with Underwriter's Laboratory Standard UL 181A; check the labels. Guidance 2: Monitor temperature and humidity while commissioning or recommissioning the HVAC system to ensure humidity control is functioning effectively. • Inspect supply diffusers and the ceiling around diffusers for dirt and dust that can indicate dirty ducts or missing, inefficient or bypassed filters. Note that dirt and dust patterns on supply diffusers or ceilings do not necessarily mean the HVAC system is the source of the dirt. The vortexes created as air exits the diffuser can deposit dust from the ambient air onto surfaces. • Penetrations in the return plenum may draw outdoor air into the system. If it is hot and humid outside this can cause condensation on chilled surfaces, in internal building cavities, or in walls or ceilings. Monitoring temperature and relative humidity in the building, supply air, return air, and outdoor air during HVAC commissioning or recommissioning allows tracking of humidity sources. The absolute humidity or humidity ratio can be calculated from these data and mass balance can be made to determine whether there is a source of humidity on the return side of the system. • Send dirt and dust samples to an environmental laboratory for microscopic examination to determine whether the particles look like soot, lint, mold, sand or something else. • Look for mold growth on diffusers supplying cooled air to the space. Condensation caused by cooling the diffuser below the dew point can support mold growth. Clean as needed and determine what actions are necessary to prevent condensation. • The dehumidification performance of the building commissioning or recommissioning should be tested when the building is occupied. Verification of HVAC System Operation Maintenance Return Air Plenums Set inspections and routine maintenance efforts in accordance with equipment warranty requirements. Appendix E contains a sample HVAC inspection checklist. Inspection records should be kept to track the results and any subsequent repairs needed. • Return air plenums are spaces that do not have ducts and typically are found above T-bar ceilings— suspended ceilings—and below the roof or floor deck above. Dust, mold and other contaminants within the space can migrate back to the HVAC REFERENCES American Society for Testing and Materials. 2003. Standard test method for determining air leakage rate by fan pressurization. E779-03. Pennsylvania. American Society for Testing and Materials. needed to determine ventilation rates for differing occupancies plus a number of design, operation and maintenance requirements to ensure proper performance of ventilation equipment. Section 6.2.8 specifically deals with exhaust ventilation. Standard 62.1 applies to many situations.) American Society for Testing and Materials. 1996. Standard test methods for determining airtightness of buildings using an orifice blower door. E1827-96. Pennsylvania. American Society for Testing and Materials. International Code Council. 2003. ICC International Plumbing Code. Sections 312.2 to 312.5. Washington, DC: International Code Council. (Sections 312.2 to 312.5 of these codes specify a gravity test of the drain and vent side of plumbing systems.) American Society of Heating, Refrigerating and Air-Conditioning Engineers. 2004. ASHRAE Handbook of Fundamentals. Ventilation for Acceptable Indoor Air Quality. Standard 62.1. Atlanta.,GA: American Society of Heating, Refrigerating and Air-Conditioning Engineers. (The ASHRAE ventilation standard provides information 102

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