[Theodore2]

Hi,
I want to make a "boiler room" in the basement around my oil-burner (hydronic heat system). I know the vent pipe from the furnace to the chimney is called a "flue vent connector" and it's currently an 8" diameter single wall metal pipe. I also read that I'm obligated to have 3ft clearance to combustibles with this current condition. Coupe of questions:

1. Does anyone have experience with changing this to metalbestos pipe, or some other "zero-clearance" vent pipe to allow me to build a wall much closer?

2. How close can I get? (of course, I need to allow space for someone to remove and clean on an annual basis).

3. what's the definition of "combustible material?" sheetrock? metal studs? a fire-rated door? wood 2x4 behind 5/8" sheetrock? wood 2x4 behind 1/2" concrete board??

4. Anything else I should be looking out for when considering this? i.e. support straps from ceiling due to additional weight? specific manufacturers to consider?

_Not_ doing this myself, but I want to be knowledgeable when someone comes to bid on it.

Many thanks,
Theodore.

 

[beenthere]

I believe you'll find your clearance requirement for single wall is 18".

 

[Colbyt]

From things I've read I think local codes sometimes are more strict that what the MFG states. Here 1" clearance to combustible materials is all that is required for double wall pipe. Six inches for single wall in a conditioned space. Double wall required in all UN-conditioned spaces.

Double wall pipe is about twice as heavy as single wall so no real load.

"Combustible material" is going to depend on the inspector's definition. Wood is a definite yes. Drywall (fire rated) can go either way. Concrete board may be approved or may require 1/2" air space between the board and the under-lying wood (local codes again).

My furnace requires 1" spacing on the back and sides and the vent goes up. I am having a hard time understanding how walls will be a problem for you.

 

[jimn]

Get the manual for your boiler and get the clearances required . Leave enough room for servicing and even replacement at some time in the future. Also be aware of the make up air requirements for combustion .

 

[roughneck]

If your closing in the room, as stated above, be sure to make necessary modifications to allow for combustion air supply from outdoors.
Venting may be a good idea as well, as fully enclosed mechanical rooms can build up a lot of heat.

 

[Theodore2]

Yes, boiler manufacturer manual gives me min clearances, and also local fuel code requires 18" around boiler (as well as single wall pipe... thanks for correcting me). And yes, I am very aware of air requirements for combustion. I guess I'll have a discussion with the local inspector about what's a "combustible" wall assembly. That's probably the best way.

I have a follow up related question, so I'll start a new thread. Thanks all.