Winter energy saving tip for AC ducts.

[willshak]

Just a hint. In the winter, my air conditioning ducts, with the AC handler in the uninsulated attic, let in a lot of cold air. Although there are movable vanes inside the vents that can be shut, usually with a screwdriver, they are not airtight. So how do I stop the air infiltration? They sell magnetic covers for the metal vents, but what about plastic vent plates which I have? I used to cover my plastic vent plates with pieces of plastic wrap that I taped on. It was time consuming trying to hold the thin floppy plastic film and tape it on at the same time. In the last couple of years though, I use the Contact Paper type of self sticking plastic shelf covering. Just cut it to size, peel the paper off to reveal the adhesive, and stick the plastic to the vent plate. I use the white kind so it hides the vent vanes, leaving the whole plate white, but that's only a matter of aesthetics, the clear kind, or any of the various colors and patterned types, work as well. Don't forget the AC return vents too.

[Joe]

[hrhofmann]

Take the vent covers off and put plastic or al\uminum foil on the back side of the covers, and then put the covers back.

[The Daring Dufas]

You could always use that flexible ferrite magnetic strip material cut to length to hold your covers on.

TDD

[Steve Barker]

i don't understand how the air is getting IN to the ducts to come out cold.

[Stormin Mormon]

AC handler in cold attic. Dispensing cold air. I don't see that as being at all confusing.

[Steve Barker]

Why would it dispense cold air? Why would it dispense ANY air if not running? It would seem that the air handler is a closed system, bringing air to itself from the living space and then sending it back with the heat removed. If it's not running, where is the movement?

[The Daring Dufas]

Th AC is probably separate from the heating system and the whole thing sitting in the cold attic is like it was sitting in a fridge. All of it is cooled down and the cold air being denser than the warm air inside the house would make it spill out of the ductwork. If you open your refrigerator and hold your hand close to the floor in front of the open door, you will feel the cold air spilling out of your fridge. It's the same principle.

TDD

[Stormin Mormon]

Heat rises; cold air sinks.

[willshak]

Yes, but then you have to take the covers off to remove the foil/plastic in the Summer. The plastic shelf liner just gets peeled off the vent covers in the Summer, and if you are really frugal, you might save the sheets for next Winter. :-).

[willshak]

You missed the part where I said "Plastic" vent plates.

[The Daring Dufas]

Uh, duh, put strips of the magnetic material on the other side of the vents. The magical magnetic rays will go right through plastic.

TDD

[willshak]

There is always air in the ducts, whether running or not. It's not a vacuum environment. Even if the ducts are well insulated, the cold air in the attic will cool the air in the ducts and then it drops to the lowest point and escapes out of the vents.. Your home is a closed system. Turn the heat off in your home and see if the house stays warm. It's simple physics.

[aemeijers]

When radiant floor or ceiling heat was briefly popular, and even today for people with old-style radiators, they used the little hi-pressure AC duct systems. Those outlets usually came with little O-ringed plastic plugs you could pop in the round holes to shut them off.

In OP's case, I'd either change the vent covers to metal so a magnetic cover would work, or find some clear or color-matched velcro dots, and fabricate gasketed covers that would stick to the velcro in cold weather. One dot at each corner should be plenty- the covers can be very thin, and the thin foam self-stick stuff applied to the back of the covers would make an adequate air seal. Basically like how they used to attach the the front grilles to stereo speakers, back when stereos had speakers in wood boxes. Most sewing/craft/hobby stores have velcro, in a wide variety of colors. Overpriced, but you won't need much.

-- aem sends...

[willshak]

Try it and get back to us. Those magnetic strips won't attract each other with a gap of only a few millimeters of space between them. I have used them. Also, the price of that magnetic material to cover 12 vents "on both sides" will be a hell of a lot more than a roll of shelf paper. Besides, like putting the barrier behind the vent cover as someone else said, my way doesn't require removing the covers twice a year.

[The Daring Dufas]

At least the magnetic covers would automagically blow off when you turned on the AC. *snicker*

TDD

[willshak]

on 12/11/2009 10:11 AM (ET) willshak wrote the following:

Thanks for all the suggestions and comments. A picture is worth a thousand words, or threads. :-)

ceiling vent cover is 12" square.