Heating and Cooling rooms with high ceilings

Mr. Blonde

I have house that I'm going to be doing and all rooms have 9' ceilings while the living room is 16'. The whole house has a flat rubber roof with the ceilings attached to 12"
I-joists directly below the roof. The house will have icynene for insulation. The living room is 39'x16'with the south and west walls exterior. The west wall has no glass but the south has 392 sq.ft. of glass. I'm designing the duct system per manual D but I can only get my returns up roughly 9' and was wondering if this is going to be a problem? Do I need to worry about pulling air from close to the ceiling/circulating the air or not worry about it because its above the actual occupied space?

tom_49

Are we talking heating or cooling?

ChasMan

Looks like both in one duct system.. Ahhh, those were the days :-) I know I wouldnt want the fuel bill of that room. I have a 12 ft cathdral ceiling in my master bedroom. The heat is shut off. There are two insulated zone walls between it and the rest of the house. When the doors are closed it will suck a dust bunny in from 10 feet away.

Mr. Blonde

help?

johnl45

The location of returns is not near as important as an unrestricted return air path to the air handler from every room allowed by code.

Constantin

I'd go with the advice of the pros...

... worry less about the location of the returns and supplies and more about getting them sized right. With the right set of difussors, a supply 9' up should be fine at mixing the room air supply, if that is what you want.

Besides, if the insulation is applied thick, the largest amount of heat loss and heat gain may not be by the ceiling, it may be via the windows or doors. At least in my house it is.