Can a furnace air return duct be made out of plywood?

Question

I'm thinking of using plywood instead of tin. can I "wood" right up to the furnace? Of course on the return side only.It is a gas furnace.

Answer 1

You can't wood right up to the furnace, code doesn't allow that. As for using plywood up to a safe distance away from the furnace, you could but I wouldn't recommend it. That's because it's organic and combustable, not to mention you're basically going to be breathing in wooden dust particles if you were to set it up. If you aren't too worried about your health, or the major decrease in efficiency of the air velocity of your returns/system (as wood does not provide a smooth surface for air flow and would create frictional resistance against the flow of air. That's why dust particles can be easily caught on wood), then yeah go for it, but from what I can make of it, it's not a good idea.

Answer 2

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Answer 3

Cold Air Return Ductwork

Answer 4

A little confusion going on here. 90% of return air ducts are the space between the wall studs an sheetrock. Metal is used and insulated on the supply side because of condensation, there isn't any condensation problem on the return side. But building codes are built on what COULD happen, not on what would happen, so it won't pass.

Answer 5

If you are planning to start on your woodworking project, this isn't something you should use, it's something that you would be insane not to. Go here https://tr.im/TMi81
Truth is, I've been a carpenter for almost 36 years, and I haven't found anything like this for less than 10's of thousands of dollars.

Answer 6

Yes, you may use wood for returns BUT only to within 3 feet of the furnace. You must use non-combustible material within 3 feet of the furnace. Go for it.

Answer 7

Code doesn't allow it. The general philosophy is that large clumps of particulates or dust could somehow make their way into the combustion area and create a fire hazard. while tin is a slick surface that facilitates a constant flow of any material so that build up is uncommon. Or so I hear.

Answer 8

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Answer 9

You can, but its not neccessary. The cold air return is just pulling room temperature air to the funace for heating. The air is not in the ductwork for long enough to make a difference in cost of heating or temperature rise.

Answer 10

check your local building codes and follow them.. wood has been used for years for return air in some areas but it may not meet code in yours. what can be done and what should be done is often different.

i would use something else, maybe just joist panning but rather sheet metal or something like the aluminized cardboard previously mentioned.