Heat Pumps and Electric Heating - Closing return air vents in the winter

When it gets below 30 degrees i turn off my heat pump, which is 12 years old. I was told it will not extract heat from the air outside at temps below 30 degrees. So my questions is, to keep air from escaping from the ceiling vents in my air conditioning system, i just close the vents off and if i don't feel cool air drafting in from them, i know they are pretty air tight and energy efficient. Am i right to assume this.
Also last year i took the vents off my return air duct and put saran wrap around them to keep the hot air from escaping. When i took the vent off to take the saran wrap off, the saran wrap was dripping wet.
The temp in that room was 65 all winter. What caused the water? Would this do any damage to my duct work? How can i keep air from escaping from this vent this winter and not have the water problem?
I appreciate your immediate response as winter has come early this year.
Ron
from ohio

Ron - Your logic on closing vents seems safe to me. If you aren't running the heat pump, then the vents would act as a heat escape so closing them seems smart. Incidentally, how are you heating if you aren't using your heat pump below 30 degrees? As for the saran wrap issue, my guess would be that the water you saw was from condensation. If the temperature on one side is warmer or colder than the other side, you end up with condensation. Similar to putting a warm food dish with saran wrap on it in the fridge - you get water build up on the saran wrap. I think I'd skip the saran wrap this year. Don't know if the water would damage your ducts or not, but in my experience, loose water in a house is never a good idea.

I always cover my AC vents, when the attic gets cold, a very noticable amount of cold air can be felt coming down into the room(s). In the attic, I caulked all the boxes to the sheetrock and verified that the flex ducts were securely connected to the boxes to ensure I was not letting unconditioned air in.

I've dumped a gallon of water out of poorly insulated ac ducts in the attic, and it was nasty water. You need to prevent warm moist air, like the air inside your heated home, from coming in contact with any cool surfaces. 70 degree air at 40% relative humidity will deposit it's moisture when the temp reaches the dew point, I'm guessing but in the range of 30 or 40 degrees. All ducts need to be air tight and very well insulated. Much more than just the foil bubble wrap most get or the flexible ducts that seem to be insulated. Air sealed and buried in insulation and not only should your current issues be gone, but your summer ac costs should be lower.

Bud

When i my heat pump goes off, i use electric baseboard. Last year i was going to try a eden pure heater or one of those amish heaters, but the company in my area that services me, area electric, told me if i was heating with electric, it would make no energy savings to me since the eden pure uses electric also. Do you concure? The house was built in 1972 when there was a shortabe of natural gas. This year i have taken special care to close up as many places as possible. Another question in closing off the return air duct. If i would use say 1/2" foam instead of the saran wrap to keep the heat from escaping into the vent, do you still think i would get condensation? Just asking. The vents in the ceiling, if i don't feel a draft from them and they are warm is it ok just to close them up with the handle that is on the unit? Thanks for all your comments i enjoy your comments.
Ron

I would like to introduce you to a new product called the AC DraftShield that will address your problem. Hook on this handy plastic cover and this will eliminate your draft coming from your AC vent. I used these covers throughout my home last winter and especially noticed I eliminated the draft over my computer desk. I am also able to reuse them again year after year.

On your heat pump, do you know if you have back up heat in the air handler? (electric heating coil)

A heat pump still can heat the house sometimes down to 20˚, and still be far cheaper to heat than the electric base board heat.

Where do you get the ac Draft shields? I have a air handler which they told me is a heat strip. They told me I could use it to heat my home when it gets below 25 degrees. I have not done this because I thought it might cause extra wear on my unit. Also, the dry air is not that good on sinus.
Thanks again for your comments and help. I look forward to your continued comments.
Ron

Have you tried running it when it gets colder out? If not, give it a try and compair to your past electric bill.

The air is not going to get any dryer than your baseboard.

I have run the heat strips and I don't think the house is any warmer than the electric heat. Also, the heat strips blow dry warm air, where the electric baseboard radiats heat, w/o dry air.
My neighbor runs hers and says her electric bill is less, but also runs a humidifier.
Ron

I think whoever told you that a heat pump is less efficient than resistance heat at 30F has no idea what they're talking about!

This is just a sample of one, but other makes and models are doubtless similar. This just happens to be one of my units. Notice that the efficiency stays about 1.0 (resistance heat) all the way past -10F. Even a 12 year old unit that's in decent condition should operate down to around 5F or less.

Amana ASZ18 Heat Pump

http://i726.photobucket.com/albums/ww264/gunrunnerjohn/eff.jpg

The AC Draftshield is designed for dual system homes having a separate system for heat and a separate system for air conditioning. the AC Draftshield when used as the manufacturer suggests you isolate the entire system by covering all of the AC grills. You can find this products at efi.org/acdraftshields.com.

Gee, imagine that, we have a spammer! :rolleyes: