Should I seal my forced air return?

Old 02-09-08, 07:31 AM
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Should I seal my forced air return?

My house was built in 1882. The natural gas forced air furnace (already installed when I bought the house) is located in an unfinished, unheated, basement and there is a fresh-air vent installed.

There is one large return vent in the living room floor that runs through the floor joists. The vent is from a previous heating system, and the new system's return is tied into it. But, it's not sealed. The return vent from the furnace just extends into the existing return duct with unsealed open space about 2" all around the return duct going back to the furnace. So, when the furnace is running, in addition to pulling air through the return vent it's also pulling air from the basement.

I'm not sure why the installer didn't seal the end of the return vent so it's not pulling air from the basement, but before sealing it I want to make sure there is no practical and/or safety reason for this installation.

It seems to me that my house would be heated much more efficiently if the return vent is sealed, and I shouldn't need to be concerned about fresh-air intake since there is a fresh-air intake vent properly installed, and there aren't any heat vents in the basement.

Should I seal this return vent?

Last edited by ghcjr; 02-09-08 at 07:33 AM. Reason: typo
Old 02-09-08, 02:44 PM
Jay11J's Avatar
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Location: Rochester, Minnesota
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Is that the one and only return in the whole system?

It could be that the only return is not large enough to to return the right amount of air to the blower to advoid any system issues.

Take a photo if you can for us to see for sure.
Old 02-10-08, 10:19 AM
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Location: Mountain Williams Missouri
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Not sure just what all you have there in the duct work. But with most open basements we put 2 registers in the duct work to let air out down there and also a small return on the cold air duct. To let heat and AC out down there. It is not a lost as it helps warm the floors and keep it dry down there.

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