I am having a new air conditioner installed including new duct work and a ceiling return. The unit and duct work are in the attic as well. My question is if I turn just the fan on in the winter will it help circulate warm air or do you guys think it would have a negative effect? Other specifics are the wood stove is in the basement and a split foyer. The woodstove does a good job heating the house. Just curious for those really cold days. Any thought?
Make sure that whole system is well sealed and insulated if going into an unconditioned space. Usually, that doesn't work well, but there have been exceptions. Nothing wrong with giving it a shot.
I installed a retrofitted AC last spring. It doesn't help in the winter. I have a 2 story colonial house. The return is at the top of the stairs. My stove (insert) is downstairs in a side room. Any wood fired heat that gets to the return is far from the source, thus it cannot directly circulate heat. The other way for it to work would be to have the system return cold air to the stove room only and close all of the other vents. But since my one return is at the top of my stairs that would prevent wood fired heat from getting beyond the top of the stairs. On top of that the insulation in your ducts will be so thin and your attic being unheated will cause even more heat loss. I put some thermal probes in my vents and only saw colder air at the output, it was losing heat. Not to say it isn't possible, but I would hedge a bet that it will be a net heat loss.
I agree with papa,you got a chance it may work.Attic is worst place for ductwork,a/c or heating,but sometimes no choice.
I have put many a AC unit in attics without any issues. Make sure your installer knows what he is doing as like anything if done improperly it can have some problems. Make sure the register boots are properly insulated if they are metal to keep them from sweating along with the trunkline ductwork, return ductwork, and all of the runs. Also make sure they have a full drain pan installed under the unit in case there is ever a leak and the ac coil should have a primary and secondary drain line and there should be a wet switch in the drain pan to shut off the unit if you ever have water in the pan. As far as using the unit to circulate air it really doesn't work that well in most applications. That being said in the winter time you will feel cold air coming through the registers in your ceiling due to natural convection however I don't reccommend sealing them up as I have seen a few issues where the ductwork will sweat just a bit in the winter time and if there is no air flow at all can cause mold issues.
He has addressed all these issues for the install. Thanks for mentioning it though. I did pipe covering and duct wrapping for a short time after high school so had a little knowledge, not much of the need for good insulation. Thanks for the heads up about not sealing them up in winter. If I just close them the way they are made to that should allow for enough air to keep mold from forming right?