Chimney pipe and stove pipe hotness

[jstellfox]

Is it normal for my horizontal through the wall class A chimney pipe section to be hotter or as hot to the touch than my double wall stove pipe is? I would have assumed the stove pipe would be hotter. The only section of chimney pipe that is hot to touch is my through the wall section, as the tee and up outside is just warm to touch. Is this a concern or normal? Thanks

 

[SteveKG]

My insulated double-walled chimney pipe, the stainless "outdoor" stuff, extends through the roof and into my rooms [three chimneys in the cottage] as way back in the mid 80s that was the cheapest and simplest way around here for me to do the house construction. From the chimney pipe I run a short section of single-walled black stovepipe. One stove has a 30 degree elbow of the chimney plus a 24" section of chimney running over to the stove. All of the insulated chimney sections get warm to the touch. If I am really cranking the stove, the chimney gets too hot to touch more than a second or two. I have never crawled out on the roof to check the outdoor section. But in any case, yes, the chimney pipe gets warm, even the insulated type. I happen to have Metalbestos [or Selkirk or MetalBest, depending on who is talking].

The insulated chimney pipe is rated for 2" clearance from combustibles. Or, my brand is. I have no experience with other brands. When the pipe is hot, I have run my fingers over the nearby wood [roof decking] and the nearest drywall, and it has never been warm, so the pipe is not heating up my walls or roof.

Therefore, either you and I are in a distinct minority, or it is normal to find the chimney pipe warm or hot. I have to admit, it surprised and concerned me when I discovered mine getting so warm, but in 25 yr., I've never even felt the nearby structure become affected by it.

 

[Backwoods Savage]

Mine get pretty warm as I would not want to hold a hand on it but I have never put a thermometer on it to check. I'd have to do that outdoors and not sure I'd get a true reading. I think perhaps with the pipe running horizontal the top will get pretty hot because heat wants to rise. If it were vertical then the heat will go only up and not horizontal.

One thing though. That horizontal section has to have some rise to it. 1/4" rise per foot minimum recommendation. We put ours at 1/2" per foot. We've had horizontal before we put in the new chimney and have never had a problem.

 

[jstellfox]

I don't think it has any rise to it, as it is pretty much level...I guess that was our mistake on install. It doesn't affect my draft as that seems to be fine even in this warm weather. Is there any other negatives to having a level horizontal run opposed to a slight 1/4" rise?

 

[Backwoods Savage]

The only negative I know of is you might get more backpuffing and have to run the flue a bit hotter than normal to stop this.

 

[oldspark]

How long is the hortizontal run?

 

[jstellfox]

Well I do have a basement install to heat the upper floors so I will likely burn hot. I have not noticed any back puffing as of yet. My flue is 26ft so maybe that will also help

 

[jstellfox]

horizontal run is only about 30-36". The stove pipe connects to my horizontal chimney pipe section about 10" before the wall. So my chimney pipe is extended into the basement 10". This is the section thats getting hot to the touch. I guess that its normal though is what I am kind of hearing here

 

[Backwoods Savage]

With that much chimney I doubt you'll have much of a problem.