Class B Venting

[Best0186]

I am installing a 75,000 BTU Modine Hot Dawg heater. It will be vented vertically with double wall vent pipe, through the insulated attic (Blown-in fiberglass). Can I blow-in the fiberglass insulation and have it be in contact with the pipe?

Thanks

 

[brewchief]

No you need a 1" clearance, a piece of single wall pipe 2 sizes larger is an easy way to do it, 6 inch pioe for a 4 inch b vent.

Sent from my SM-G965U using Tapatalk

 

[Best0186]

Thanks, I was looking at the class B venting and it said 1" clearance from combustible materials. I didn't know if fiberglass blow-in insulation was a combustible.

 

[Jackfre]

Whenever you see a clearance you are best of to simply observe it. Splitting hairs with your insurance adjuster is not a winning hand

 

[cadunkle]

The few times I've done B vent through a ceiling I've used a firestop support and boxed out the framing to ensure clearance and no insulation can touch the vent. I nail flashing to the box so it's a noncombustible surface and extends above the level of insulation. Use a ceiling collar on the inside to cover gap in drywall or whatever ceiling finish material you use.

https://www.ameri-vent.com/products/fsp/firestop-support