Green Remodel Forum

So I've wondered for the last six months that we've been in our new house - why is the cold air flow into the master bedroom so low?
The bedroom is an addition that was built in the last few years during the most recent renovation, but its only a 1900 SF house so we were hoping to avoid adding another A/C unit. Then it got cold out and I realized we weren't getting much heat back there either -
Went to peek in the attic and surprise!

http://twitpic.com/7v8r1u
We've been heating our attic.
I fixed it for the time being with some Gorilla tape, but now I'm wondering if I should get a professional to climb up there and make sure we don't have any smaller leaks.

There are lots of leaky ducts in homes and disconnected ducts are not uncommon. Use mastic and UL rated aluminum tape to do the job. Mastic is a water based duct sealant that does not off-gas any VOC (volatile organic compound). First, use rubbing alcohol to clean the leaky areas. Use a foam brush to apply mastic on them. After the mastic is completely dry. Wrap aluminum tape all the way around the ducts to make them look neat. Add R-8 insulation to ducts to prevent heat loss. For disconnected ducts, screw them back together and follow with same procedure as leaky ducts.
Now you are heating/cooling your living spaces instead of the attic.

Yes, it happened to us too. We had an home performance contractor did some tests on our house. Sure enough, he found one of our ducts disconnected in the crawlspace. We fixed the duct ourselves but did not fix the air leak. I probably hire the guy to do it when the economy improved.

Actually, air sealing the joints and the air ducts can save you more energy than just connecting the duct back together. Air sealing is not hard. It just takes a lot of time and patience. You can do it yourself by using the mastic to seal all the duct connections so that you are not heating your crawlspace. It also prevents sucking the stale air from the crawlspace into the house. Use Great Stuff to seal the rim joist to prevent cold air coming into the crawlspace. You can get both products from a home improvement store.

My Heating contractor is going to replace a couple of our crushed air ducts with flexible ducts. Are they better? He said he does not use aluminum ducts any more. To me, aluminum should work better because it has smoother surface, less friction.

dia, you are correct. Aluminum ducts do work better. Many heating and cooling contractors stop using aluminum ducts because flex ducts are cheaper and easier to work with but they are less efficient. You can insist your contractor to use aluminum ducts. You may have to prepare to pay more.

For the long run, if the aluminum ducts are more energy efficient I'm willing to pay more, hopefully not much more.

I wish I knew about this earlier. I let my contractors replaced them with flex ducts.

Thanks for sharing with us shmoo. Isn't it a good idea for everyone go to your attic, basemen, or crawlspace check the ducts now? Hopefully, you are not paying to heat your attic/crawlspace.