Cold Air from Central AC Ducts/Vents

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jatoxico

jatoxico

Minister of Fire
Aug 8, 2011
4,369
Long Island NY
With my house layout I'm pretty sure I get circulation of air through my central air in winter. Guessing that warm air spills out of the stove room and flows up the return then cool dense air drops from the vents. Anyone else feel this is an issue and do you do anything about it?

I close the shutters on each vent which helps I suppose but they don't seal too well. Should I seal the return, what with...plastic sheet?
 
I get the same issue on my 1st floor vents but i dont feel it on the 2nd floors. I sealed return vent with dow board and tyvec tape the other day, made no differance.
Im thinking the air handler and ducts in the attic just get cold and the cold air goes to the lowest point which is 1st floors vents.
I air sealed everything i could on the air handler and ducts while i was insulating attic. Im gonna make vent covers somehow when i get some time
 
I have vents on three levels. Not too cold in the attic yet but in winter temps I think you may be right about the lowest vents. I'm mainly concerned with my return which is about 2'x2' and possibly allowing circulation.

There's not much out there on this topic and what I've read was that closing the shutters ans sealing the return didn't do much as air still dropped. Plus not so sure I want to seal entirely for fear of having a moisture issue.

My return is perfectly placed to soak up warm air and can be helping my issues with the stack effect. Still I don't know if I'm getting that much air flow and am just wasting my time by closing the return or not. Hoping someone has some experience with this.
 
The air handler in the attic is classic for this. Not good for mold either. I went to a ladies house and she actually had ICE coming out of her ducts in the attic. The warm moist air raises up into the ductwork condenses on the cold metal, runs to the low point and freezes as it leeks out. Wish i still had pics of it. You either have to insulate the crap out of the ductwork, or use plastic and tape to seal it all off. Both supplies and return..
 
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So as a quick check the vent in the stove room measures 61 deg F and other metal objects near like the ceiling fan are 69. You can feel the cool air. Not sure how much blocking the return will do but gotta be better than nothing.
 
20160212_203816.jpg 20160305_141822~2.jpg

Whats the r-rating on insulated ac ducts?
All my ducts are insulated but how much does it really do. I had big gaps on the air handler they didnt seal up and the return vent frame was even worse. I great stuffed every vent that was attic mounted. Prolly helped but the rest is gotta be the vents running through the attic.
My house is def staying warmer!
 
jatoxico said:
So as a quick check the vent in the stove room measures 61 deg F and other metal objects near like the ceiling fan are 69. You can feel the cool air. Not sure how much blocking the return will do but gotta be better than nothing.
Click to expand...
There's no harm in trying temporarily taping over the return with plastic or cardboard and noting results over the following days. Just be sure the unit can't come on as this could damage the blower. Is this the only return?
 
Yes only return. System was added around 15 yrs ago and is only for the AC and the whole thing is shut down for the season. I put a sheet of heavy plastic in the return and see what happens.
 
I def didnt feel much of a difference by covering return but i feel its still good to keep the hot ceiling air in the house rather then up in to the air handler.
 
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You have to do all the supplies also,. Air will go up some supplies and down others. Its a long piece of duct with many branches. So if you only had 2 supplies air would go up one down the other.
 
cableman said:
View attachment 187482 View attachment 187483

Whats the r-rating on insulated ac ducts?
All my ducts are insulated but how much does it really do. I had big gaps on the air handler they didnt seal up and the return vent frame was even worse. I great stuffed every vent that was attic mounted. Prolly helped but the rest is gotta be the vents running through the attic.
My house is def staying warmer!
Click to expand...

Generally R2 some good stuff R6. Thats in perfect condition, with a perfect install.
 
I went through this, having AC with the air handler in the attic. I got some large flexible magnet sheets that are white on one side. I trimmed them to fit on the supplys and returns, and put them on for the off season. It cut down on a huge amount of drafts in the winter.

Like this stuff. https://www.amazon.com/dp/B005HY9KDM/?tag=hearthamazon-20
 
Following up, after adding some heavy sheet plastic sheet over the return I am no longer feeling any air movement from the return the vents and they are measuring the same temp as other objects in the room. Surprised how well this seems to have worked to stop the air flow.
 
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Good to hear that worked. Cold air can convect pretty well. Flip the breaker for the system and leave the return covered until summer.
 
Done. Really surprised how much air movement I get but the layout is ideal for it.
 
I've debated on what to do with my ducts - in the past I covered them all up including the return and that cut down a lot of the drafts and cold floor - but I also had a lot of air infiltration into the basement then. Problem is I'd forget about them when I decided to turn the furnace on and wondered why it wasn't working to well. Decided just to leave em all open this year and I don't think the furnace has run once in a month or so, go figure.
 
A buddy of mine just built an energy efficient house and his hvac guy said the ac ducts should be the same temp as house. Hes also getting moisture dripping from them.
Theres no way im keeping mine warm, theres just too much of it in the attic and not insulated enough. I taped paper to my 1st floor vents, last year i stuffed towels in them! These are the only vents i still feel a cold draft and thats even with the return covered.
 
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