Return air

Can anyone tell me why a house approx. 1000-1200 sq. ft. would only have one return air in the great room? There is nothing in the other rooms. The furnace is a Carrier, 53,000 btu.




Are the doors to the other rooms “undercut” to provide air movement under the closed door?

No. There is a returned vent in the closet where the furnace and water tank are, that gets intake air from the attic.

I see this on a regular basis. I explain to my client that the return should never be blocked by furniture and that all doors should be open or undercut to allow circulation. I also state that, if after they are in the house for a while and still do not get adequate circulation, they should get an HVAC contractor to provide a solution.
Most of the houses with a central return will also have one in the master bedroom, but no where else. It really comes down to money, the more returns, the more it costs.


“There is a returned vent in the closet where the furnace and water tank are, that gets intake air from the attic.”

Is the return pulling in air from the closet, or from a duct on the closet wall? If the first, I would be concerned about it. Is the water heater gas fired?


Its pulling air from the vent on the wall, which is pulling from the attic air. Yes, the water tank is gas fired.

I do small homes all the time with only one return. Without more info., I wouldn’t have a problem with it.

Gary, that’s common around here. I inspected on like that this very day.

Heck–I even installed some that way 40 years ago when I didn’t know any better. If I should inspection one of those houses today, I would say terrible things about that installer.:smiley: :smiley: :smiley:

Do you write it up? Or so long as the doors are undercut, its ok?


Is there a hissing sound from return? Is this a two level home?

Insufficient return air usually will hiss.

I write the doors, if undercut, are an adequate return system–keep the doors free at the bottom for air passage.

Sounds like you mean combustion air here.


 If I am understanding you correctly, it sounds like some of your "return air" is coming from the attic space.  Any air from the attic should be for (fresh air) combustion air only due to gas appliances in a confined space i.e. gas furnace and gas water heater in a closet.  The **fresh air should not** be for "return air" circulation for for the living space.  Knowing more about the layout of the home will conclude if the one return in the great room is sufficient or not.  

Joe Nichols
The HomeBiz Inspection Team
Frederick Co. MD
NACHI member

Combustion air can come from the attic. Return air for circulation usually comes from the building interior and here in Texas 95 percent the homes I expect have only one return air grille sized appropiately. The doors should be cut a mininum of 1" in this case for air return circulation. If there is a natural draft gas appliance (water heater) near the return air grille this would be a hazard as backdrafting of the water heater becomes an issue.