# Running a heat duct down the inside of a wall



## JoulesWinfield

Just wondering what the standard approach is to running a new heat duct down the inside of wall.
The wall in question is 2x4 construction and is not funished but will be drywalled soon after the duct is installed.

Also would the same practice be applied to the return?


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## glennjanie

A 3" X 12" duct can be run in a wall but is limited in cfms to somewhere around 100 to 150, which will heat a small room (10' X 12'). If you need more than that you could run more than one duct. Return air can be run without duct. 
Glenn


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## JoulesWinfield

So is the 3x12 duct something I can buy or would I need to bend it up myself?

Also since only one side will be drywalled for now should I just cover the other side with a peice of sheet metal?


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## glennjanie

Oops. The standard size is 3-1/4" X 10" and it comes in 2' sections. It is made by Gary Steel Mfg. and should be for sale in your area at a Heating and Air Conditioning supply house. I would not worry about covering the back of it.
Glenn


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## JoulesWinfield

I was thinking there would be something like that. I found the piece that goes from the 6" duct between the joists and 90's into the wall. But I couldnt seem to find the actual duct that would extend down in the wall.

A friend of mine suggested just putting sheet metal on both sides and mounting the register on the drywall. That really didnt seem like the proper way to do it.

Ill have to check around to find the local supply house.

Thanks again Glenn.


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## Daryl

THey also make an oval shaped ductwork for the supply line (one that delivers the heat to the room) which will fit in the confines of the 2X4 wall (it's looks like a squashed 6" round ) and comes in 6 ft lengths and is available at the local HD (lowes is very limited on this item in my area). They make the end stacks for the register too as well as the connection peices to 6" round. This allows you get the CFM rating higher than 100-150. Keep your 90 bends to a minimum as this cuts down on the airflow considerably. You can use the space between the studs for the return. Just cover the open side with sheet metal to allow the draw of the air on the return to the furnace.


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