cold air coming in my ac vents in winter!! Oh no!

allonmyownDecember 7, 2011

hi, I'm hoping some of y'all know about this problem. I live in the midwest so it's c-o-l-d. We have an older home, with ac vents in the ceiling. I have a ranch, w/ a little space in attic, but we never go up there (not finished--only storage).

Almost every day, but not all the time, I feel cold air coming in through my ac vents. THe ac is not on! It's not forced air, but I can't figure it out. Any ideas?? THanks

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ionized_gw

Did this just arise after several years in the home, or it is a new home for you? There are at least two possibilities. Ducts leak. You might have a vary big one. It is time to go up there and check. Second, it is very natural for air to enter the duct system from the living space in some areas. It will cool off in the ducts and flow out somewhere else.

    Bookmark   December 7, 2011 at 8:11PM
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allonmyown

We've been here a few years, but have been too busy to address it. This winter, I'm putting my foot down bc I think we are paying to heat our home more than we should.

It is very cool air, so I can't imagine it is from another part of the house, but of course, I'm not that knowledgeable. I'm afraid to call in a duct company bc I might get sold the farm but not sure who else to call??

    Bookmark   December 7, 2011 at 10:22PM
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david_cary

Could you just cover them? - it would be the cheapest option.

    Bookmark   December 8, 2011 at 2:07PM
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ionized_gw

You may have missed my point. The insulation around the ducts in the attic might not be that great. Room air goes in, cools down and then drops out. Sometimes if the home is humid, you can get water condensing and dropping out!

You could call an HVAC company. You could get an energy rater out to your house and have them identify your low-hangning fruit for energy conservation. Your ducts will be a part of that kind of evaluation. There are often State or utility programs to pay for part or all of an energy survey.

    Bookmark   December 8, 2011 at 2:54PM
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energy_rater_la

climb up there and take a look.
is it all the supplies or just some?
make sure that the ducts haven't become disconnected
and check connections for sealant. mastic lasts..
duct tapes fail.
check the supply box where it rests on the attic floor
got a gap there?
whats the insulation in the attic like?
is it something you can address or do you need
more than you can comfortably do?

best of luck.

    Bookmark   December 10, 2011 at 10:41AM
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brickeyee

The ducts WILL cool to the attic temperature, and as ionized clearly explained the heated house air will rise into them, cool off, and ten sink back into the house.

Ducts in an unconditioned attic need to be closed off during the winter.

Close the vents using any control they have, and if they are still leaking remove the grill and place cardboard over the opening, than put the grill back up (paint the cardboard if you want).

Unico systems (high velocity systems) are most often used for cooling, and they come with plastic plugs to close the vents during heating season.
The plugs also prevent condensation in the flex ducts.

If you have sheet metal ducts the condensation is more of an annoyance that anything usually.

In Ductboard or flex ducts it can damage things if it freezes.

    Bookmark   December 10, 2011 at 3:14PM
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energy_rater_la

are a/c vents also heating vents?
thats how we do it here.

    Bookmark   December 11, 2011 at 10:38AM
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brickeyee

"are a/c vents also heating vents?
thats how we do it here."

Condensation can still occur unless the heat is turned on and operating.

Even then, if the ducts are poorly insulated (you will get a blast of cold air when the heat comes on) you can still get condensation between heating cycles.

    Bookmark   December 11, 2011 at 2:06PM
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energy_rater_la

true, but it is a logical question when
you recommend closing them off, esp with card board.

    Bookmark   December 11, 2011 at 7:26PM
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ionized_gw

Geeeze, I interpreted, " It's not forced air" as there is some other heat source, hydronic maybe. That might have been a big mistake. The OP seems to be MIA anyway.

    Bookmark   December 12, 2011 at 7:56PM
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allonmyown

SOrry, I am back. Thanks so much for ideas. HEat comes from the floor from the furnace. Airconditioning comes out ceiling.
I will take a look. Thanks.

    Bookmark   December 15, 2011 at 10:59AM
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