Forced Air Furnace Vent Clearance Question

[jstonemo]

I am finishing my basement and have a question about clearances next to the single wall vent. The wall between the stairs and furnace only allows for 3" clearance next to the vent pipe unless I turn the stud sideways to gain an extra 2" of clearance. This is still short of the 6" clearance for single wall vents.

The furnace is a Trane forced vent gas furnace.

I have heard that one can make the wall heat resistant for tight clearances, but don't know what or how to do it? Advice would be great.

[roger g]

I really should know this but I forget. Check with your local gas code and fire regs to see what the clearances are.
When you say single wall, it would be a C vent and the clearances are quite substancial. If you went to a B vent which is an insulated vent you can have a 1 inch clearance to combustibles. Remember it is to COMBUSTIBLES. In some cases we used to line a wall with sheet metal and have it stand off from the wall about 1 inch and that would help our clearances. Probably this new cement board would work. I'm kinda thinking the clearance is about 6 inches to a C vent. I hope you are not totally enclosing this vent.
Sometimes your local fire Dept safetyofficer can be real help though it can open a can of worms if the guy is super agressive and likes to prove himself.


roger

[rabadger]

Without looking it up I believe your clearance must be 6" on single wall

Page 80 Table 503.7.7 2003 Intermational Fuel Gas Code.
Listed equipment with draft hoods and equipment listed for use with type B gas vents. Single-wall metal pipe connectors only - 6" GAS BURNING WITH DRAFT HOODS FOR TYPE B GAS VENTS ONLY.

Check the local codes, furnace and water heater venting instructions.

[jstonemo]

I have heard there is a way to do this. Guess I need to check with the local authorities to be sure.

It is not going to be totally enclosed. The wall will be next to the furnace on that one side and the rest of the furnace will be open in a room about 9x10. The vent is a flex single wall that comes from the front of the furnace and bends around the right side and then connects to a double wall vent once it gets past the back of the furnace.

The basement was supposed to be roughed-in for future finishing, but apparently not all of the trades got the message. They put the furnace too close to the stairs leading down to the basement.

[GiantScale]

Iv never used flex.. I always installed sheet metal over wood closer than 6" Or run the Bvent all the way around. Have your inspector take a look.

[rabadger]

Do not use flex. Use 26 GA or heavier galvanized sheet metal. If you are not sure hire a professional to do it. It should not take any longer than a hour.

[jstonemo]

I didn't install flex vent. It was installed that way when I had the house built.

I just saw that some manufacturers make a type B flex vent which would be perfect for what I need. Any experience out there with type B flex vent?