A visual inspection of the exhaust fan dampers in xxx has shown that the dampers are very leaky and a significant amount of conditioned air is migrating in or out through the fan and damper assembly. This leads to drafts and discomfort, and also allows heating or cooling energy to escape.
It is recommended that the dampers be straightened, linkages adjusted and edge seals replaced to ensure a proper air seal when there is no intended air flow. At the same time, the dampers must also be balanced to ensure that they don’t blow open under normally windy outside conditions..
Issues and Concerns
This recommendation is in accordance with Section 6.4 Energy Distribution Systems of the ASHRAE Standard on Energy Conservation in Existing Buildings. ASHRAE Standard ANSI/ASHRAE/IESNA 100-1995 – Energy Conservation in Existing Buildings is an approved standard of the American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., the Illuminating Engineering Society of North America and the American National Standards Institute.
Analysis text here