Is air filter rack supposed to be airtight?

Old 11-21-06, 08:12 AM
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Is air filter rack supposed to be airtight?

My house (1 year old) has forced air heating. The air filter goes in a slot where the return air duct meets the furnace. I think it is badly constructed, the gap is larger than the filter rack (if that's what the thing is called). It's caulked up all around but on the side where the filter goes in. It cannot be caulked there, because then it'd be impossible to remove the filter.

So now there's a 1/4" gap, and when the blower runs, I can feel it pull in air from the (unfinished, walkout) basement through that gap. I suppose that can't be good, though of course I'm no expert. This way, it draws in cold air from the basement (which will probably be replaced with even colder air from the outside), instead of through the air return. Besides, the manual for the furnace says this should be sealed in order to avoid the danger of drawing in flue gases (though the furnace is the kind which draws combustion air from the outside).

So is that 1/4" gap okay / not great, but acceptable / needs fixing?
Old 11-21-06, 12:52 PM
airman.1994's Avatar
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needs fixing?
Old 11-21-06, 01:04 PM
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Ah the good old duct tape . Could you just put some duct tape on or over it so the air has to go through the filter.Tape a 1/4" board strip to it This would still let you change the filter every30 to 90 days
Old 11-21-06, 06:50 PM
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The filter slide in the side or drop in the top?

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