How close for insulation around heater vent

[turbo6justin]

I am closing up the ceiling in my garage and I am trying to figure how close to the exhaust for my Modine heater I should put the insulation. It is a 175k heater with a 6" vent that runs up into the attic and out the gable end. I of course used a thimble where it goes through the wall but I am leery about the insulation where it will go through the ceiling. The fiberglass won't 'burn' per say but how close is close. I will of course strip the kraft facing away for this section. The vent goes up and into a 45 deg a little above ceiling height so after that the pipe runs through the ceiling joist space where the insulation will be. Right now I have 10+ inches of clearance along the whole length of the pipe (24"). If I insulate under the pipe there will be contact between the vent and the insulation for at least part of the length. Is it okay to have contact with the insulation? I will use another thimble through the drywall, is the 2" or so that the thimble adds enough clearance for insulation? I obviousely want this to be very safe but want it insulated as well as possible. Looking for advice as I am coming up with nothing right now.

Many thanks in advance.

 

[trythis]

I would not touch the pipe with insulation. That spot or area will not cool like the rest and might corrode faster. I am sure there are codes against this sort of thing.

 

[csp]

What type of vent pipe are you using, single wall or B-vent?

 

[turbo6justin]

Where I am concerned about the insulation it is single wall. It is b-vent through the outside wall.

I am sure there are codes as well, I just can't find one that applies. I have tried code books as well as insulation manuals but can't find any answer. The insulation information just refers to ASME codes which are hard to find with out paying for them of course.

 

[REDSHELBY]

Should use all B-vent. 1 inch clearence for B-vent 6 inch for single wall.

 

[turbo6justin]

The single wall is heavier wall and is what was recommended by a local installer so I am not worried about that. Anyone care to second the 6" rule? I was just thinking I could also put a piece of reflective insulation on top of the drywall (in the attic) where the vent runs.

 

[padronanniversary]

6" for single wall. That's why I always use b vent