The Commonwealth Of Massachusetts Department of Housing and Community Development – Bureau of Energy Programs
The following text appears in the “Weatherization Assistance Program Technical Manual” dated April 1, 2003:
The fireplace and its damper is a potentially large hole with a built in stack that should be addressed. Occupants tend not to feel leakage around the fireplace since they tend to exfiltrate large volumes of air, creating a draft of makeup air somewhere else in the home. Homeowner’s frequently leave the damper open without realizing it. A commercially available “Draftstopper” can be used to stop the leak.