Sizing HVAC ducting

sorry ken i dont know squat about a c . ill keep my eye on your post and if no one comes along that does ill try to get my neighbor to come over and read it and see if he can help. you my be best to talk to one of your local guys though like you said there are a lot of variables

same here,...... sorry,...... not much help.

well….I have a .PDF that I can e-mail you. Should give you more than you want to know. I tried doing something about posting it to Photobucket, but, they only u/l pics. It’s alittle less than 2.5 mB. But, I found it’s a real good primer on HVAC ductwork.

-- arborial reconfiguration specialist

I’m not sure that would pass code. The danger is that if someone were to ever leave their car idling in the garage, there is a risk that the carbon monoxide could be spread throughout the house killing everyone inside. Most people end up installing a ductless A/C unit and/or heaters specifically for their garage.

You should definately check your local building codes. Where heating flows, a return also needs to run back to the furnace and there would definitely be an issue with CO getting back into the house. I think you would be better off with installing an electric garage heater.

-- Mike - Minimum code = Barely adequate.

Assuming you are now aware of the dangers. . .if it were me, I’d just use a couple of 8” supplies, and if I added a 10” return, I would use a filter grill on it, and I’d keep a good quality allergy filter in it, and keep it clean. When the system is running, it WILL draw air through that return, so all smells, etc. from the shop will circulate through the house. . so keep this in mind also. Simply shutting the louvers on the supplies will not totally close the air off, so if it were me, I’d put a 10” start collar with a good manual damper in it, then run over to the garage with a 10”, using a 10×8x8 wye to split into the ducts, then use a good damper for the return, that way you can turn it off a little more cleaner. IMHO, Christy Hicks