Common Issue: Lack of combustion air.......

[Brandon Whitmore]

What about pulling combustion air down from the attic through a 4 or 5 " pipe? If soffit vents are plentiful, are there any negative issues with that?

Pulling combustion air in from the attic is an option (needs to extend 6" above insulation level and not be screened), but not when installed in a garage.

[inspecmoore]

I'm kind of confused about the cubic ft of air. I know sq. ft. and cubic feet are two different things, so what size opening would equal 50cf?

[AHI in AR]

I'm kind of confused about the cubic ft of air. I know sq. ft. and cubic feet are two different things, so what size opening would equal 50cf?

That's an apples-to-oranges question. An opening can ONLY be measured in square ft. or fractions thereof. The room dimensions where the appliance is are used to determine cubic footage.

[Jim Katen]

I'm kind of confused about the cubic ft of air. I know sq. ft. and cubic feet are two different things, so what size opening would equal 50cf?

Cubic feet is a measure of volume. (Think cube.)

Square feet is a measure of area. (Think square.)

One measures things in three dimesions, the other measures things in two dimensions.

The size of an opening, length x width, is expressed as area in square feet, square inches, or, if you're not from the US, square meters.

The volume of a room, length x width x height, is expressed a cubic feet (inches, meters, cubits, etc.)

When the combustion air requirements for an appliance refer to cubic feet, they're talking about the volume of a room or space, not an opening.

[inspecmoore]

Yes, makes sense. Thanks.

[plummen]

Just curious, did the discussion/calculations include closets that contain gas clothes dryers?

I'll double check today, but am positive that they should be included in the calculations.

its normally a cold air return grille on both sides of door so it can be closed.

In the past I would normally bring in combustion air from out doors if possible