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Community and Q&A

Why would there be 2 air returns in a bedroom with only 1 supply?

susamayri | Posted in General Questions on

I recently purchased a tri-level home built in 1962. It hasn’t seen a lot of love over the years so I’m trying to make some cosmetic improvements before moving in. In each of the 3 bedrooms there are 2 air returns, one near the floor and the other directly above it about 6 feet up, on the wall opposite the supply registers. For aesthetic reasons I would like to close off the upper returns but hesitate to do so without understanding why there are 2 of them and is closing one an OK thing to do. Any advice would be appreciated.

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  1. GBA Editor
    Martin Holladay | | #1

    There's no way of analyzing the return-air system in your house without more information.

    We don't know the size of your bedrooms or the size of your house. We don't know the total number of cfm flowing through your supply ducts, nor do we know the total number of cfm required for your return air system.

    Are you absolutely sure that the grilles in question are connected to the return air system?

  2. wjrobinson | | #2

    Standard fare in an attempt to redistribute stratified air.

  3. susamayri | | #3

    Thanks for the replies. The house is 2100 sq ft, the largest bedroom is 13x10, 2 others a little smaller. I don't know the cfm. The grills are definitely return air. Would removing 1 in each of the rooms affect the operation of my system? I've not seen this type of set up in other homes I've lived in.

  4. GBA Editor
    Martin Holladay | | #4

    Return air ductwork and grille sizing isn't random. The area of the grilles and the size of the ducts must be adequate for the cfm rating of your furnace. Sizing these ducts depends on several factors, including the length of the duct runs and the number of elbows in the ducts.

    In general, however, the size of the main return air duct should be at least as large as the size of the main supply duct. Eliminating return grilles has the potential to starve your furnace of return air. If you aren't sure how to size return air duct systems, don't alter your system without consulting an HVAC contractor.

  5. susamayri | | #5

    I think that's what I'll do. Thanks!

  6. BobHr | | #6

    It is actually 1 return with 2 grills. If you take off the bottom grill you will see that it extends up the interior of the wall to the upper grill. The return path to the furnace will be down, below the floor level through panning and trunk lines.

    the idea is to cover one of the grills depending on the season. AC season close the bottom grill and suck warm air from near the ceiling. In heating season close the top one and pull cold air from the floor.

    Since most homes just have a single grill I would guess you could get by with closing one off.

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