There seems to be some question between my builder and his sub for HVAC.

Which location is best for comfort and energy efficiency for ceiling mounted vents, over a window or door unit or near an more interior wall that is much closer to the main plenum?
Thought is that the sooner the conditioned air from the duct gets to conditioned living space the better. The old wisdom was over the colder/warmer surfaces of exterior window? I think the length of the flex duct to get near the exterior walls loses efficiency due to heat/cooling lose in the attic. Which is better?

Regards,

Huck

Put the ducts as close as you can to the outside walls. The warm air will hit the windows and walls and work its way back to the return air. If the vent was in the center of the room you would have cold areas on all your exterior walls.

T=Top is right. Keep the outside wall area as warm as you can then the inside area will stay warm. There is the argument that the ceiling vents shoots the hot air to the walls but it is still best to have the hot air there when it comes out of the duct.

OK, sounds pretty good for winter. We are in the deep south, winters are milld. Late summers are murder, high humidity and high temps in the 90's some days until late afternoon. My new home construction sits on a lake with front to back due East to West. Lots of attic exposure to direct sun.

Any change of opinions given that with ceiling vents near outer walls and main plenum more centrally located it makes for lots of spidery flex ducts hanging all in my attic getting very hot in the summer??

Thanks

I prefer vents that face out from the interior wall. This gives a very even cooling and you can direct them to any part of the room you want. But if you want it in the ceiling, put them as close to the center of the room as possible and use a four directional register to get even cooling.

House has return air ducts located near the ceiling and near the floor and can be opened or closed. These ducts are located in the hallway on the main level and in the hallway upstairs. They run in between the studs top to bottom.

If you open the bottom ones in the winter, the cold air will be drawn back to the furnace. Close them and open the top ones in the summer to draw off the warmest air.

If you install a high and a low return and let it pull equal it will work fine. It will mix the house temp the way it needs to. (warm air from the ceiling and cool air from the floor) If the contractor is saying they need to put the supply vents in the center of the room he is trying to save money on labor and materials. Always get as close to the outside wall as you can- heat or cool. If the vents are in the center of the room you will have hot or cold spots around the interior walls. Do not use flex-duct it will cost you a lot in the long run.

The standard installation in the southeast is more commonly attic installation of the heating and cooling system with one or more centrally located return ducts, usually in the ceilings. The vents are usually placed along exterior walls over exterior windows. I would say 90% of all installations are this way. So are in the crawlspace, if applicable, but humidity and moisture seems to be a problem with equipment life under the house.