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Posted By Gasass,
Jul 12, 2013 at 6:09 PM
Is it okay for Class A to have less than 2" clearance when passing an aluminum gutter?
The clearance is from combustibles so the gutter should be ok as long as it's metal.
Well now that paint on the gutter....
So the paint will be a problem?
Don't know. Probably not just something to consider. There is so much area in the gutters it should dissipate the heat.
I've seen many painted galvalume pipes that are fine for years. Seems to me to be not much to worry about it. Most gutters are powder coated and should stand up fine even if there is only a small gap of an inch.
The only way that the paint on the gutter will be affected is in the event of a flue fire. But I doubt it would even have an effect on it then. It's pretty amazing stuff!
The installation manual will probably state that 2" of air space is required around the Class A pipe except where radiation shields are used. They specify air space because that is the best way to dissipate the heat. No manuals that I have ever seen specify combustible vs non-combustible when talking about that clearance. That being said, I don't foresee the clearance to the gutter being an issue, however, for it to be up to snuff the 2" air space rule should be followed.
The 2" air space rule is to combustibles. I am pretty sure a gutter is considered non-combustible. If I had some scrap I would try the torch on it as a test.
With class A pipe, especially on the exterior of the house, it never gets too hot to leave your hand on it. It would never be a problem.
Wow. "It would never be a problem" ?
That is a pretty bold statement. Every install is different and stack temperatures are going to vary significantly not only with every install but with every fire. Just because you have seen one or two or a hundred Class A chimney systems that "never gets too hot", does not mean that is true of all installations.
While I agree that there would probably not ever be enough heat transfer between the Class A pipe and the gutter to cause an issue with the house, the original question was "Is it okay for Class A to have less than 2" clearance when passing an aluminum gutter?" The answer is no, because you will not find any documentation that will tell you it is.
Picture this...The aluminum gutter gets packed with dead dried up leaves one year and never gets cleaned out. Now do you have a non-combustible gutter still?
The problem is with heat transfer and it happens all the time. The manufacturer tests and tests and tests to get their products listed to have a 2" clearance. If you start making your own changes to their product and god forbid something should happen such as a fire, you want to make sure they cannot come back and say it was due to a faulty install.
Again, I truly believe that this would most likely never be a problem, just thought it should be clarified so you know the facts.
Wow! Thanks for sharing all this wisdom!
Leaves in the gutters is a maintenance issue. It is very unlikely to be the source of a fire, but perhaps possible? Another case like this would be where a class A tee/thimble is at or below grade going into a basement. If leaves are allowed to accumulate around the pipe that could be a dangerous situation. Always keep combustibles away from the chimney.
Another example could be metal roofing that does not have the required 2" clearance. If the roof sheathing (combustible) is the required 2" away, would the metal be able to dissipate the heat coming off of the Class A piping as well as the required air space would have?
Your not going to get that much heat off the outer shell of the Class A.
Gutter will be fine. Have at it.