At inspection yesterday I ran accrossed an exposed 4" B-vent in a closet. Hot to the touch. Right next to the horizontal pole where coats hang. Not sure this is safe. What do you think. Enclose in chase? Stan
There is a MFG sticker on class B vent pipe that clearly states one inch clearance to combustibles most contractors in my area don’t read or are unable to read the English language or simply don’t care. I don’t think I have ever written a report that the clearance was not listed as a repair well maybe on a electric appliance;-)
Most of the B vent manufacturers specify that when the vent passes through an accessible area the vent should be enclosed with proper clearance to prevent damage or accidental contact.
Oddly, I can’t find a reference in either the IRC or NFPA 54
I would advise to enclose it.
Chuck, do you have the Commentary for 2006 IRC G2426.5?
Dang Mike. Make me drag out the old printed book, why don’t you? Yes I have it. Thanks for the reference.
In a nutshell (this is heavily abridged and paraphrased because it’s long and I suck at typing): The commentary says what the code does not. After saying that clearances, etc. may vary by mfr. It says it must have physical protection in accessible areas to prevent damage and contact with combustibles. Don’t forget firestopping…
The real requirement will be what the manufacturer states. If you got a photo of the label, you can pull thier install instructions and use as a reference.
In any case, Thanks to Mike :mrgreen:, you can confidently state that it should be protected and firestopped. But there is no model code reference to cite, unless you count commentary.
I wouldn’t want to have to type all that in manually either, here’s a cut & paste:
Thanks Mike, and Chuck.
Added to my library;
The vent for furnace is installed from the basement through a (closet), through the attic and through the roof. The portion of the vent passing through the (closet) should be protected from damage. The means of physical damage protection should also be designed to maintain separation between the vent and any combustible storage. To prevent the passage of fire and smoke through the annular space around the vent penetration through floor and ceiling, the vent should be fireblocked with a noncombustible material. Vent manufacturers provide installation instructions and factory-built components for fireblocking penetrations. Recommend to repair as needed.
Ok lets take this one step beyond conventional thinking. Why the clearance to combustibles on class B piping if in most cases the piping does not reach temps on the outer wall that would burn your hand???