how warm are chimney walls?

[vap0rtranz]

Hi,

How warm do the walls of chimnies get? I think I have a hot spot.

I have a masonry chimney with an older ceramic liner and a new steel liner inserted on top. This chimney is in the center of the house -- no exterior walls, all interior walls with wallboard. From the basement, I can see a 1" air gap around the brick chimney.

The woodstove is connected on the 1st floor.

I've noticed that one of the 2nd floor walls that faces the chimney reads upto 92F. This only happens when we fire up the stove to our max burn.

This hot spot is pretty localized. About 1' diameter. I suspect its an old wall-passthru for a 2nd floor woodstove, but I've not opened up any walls to check.

The older ceramic liner was inspected by licensed sweep and they recommended a new liner, so I installed the a steel liner. But I had the sweep come back by after I did the install to re-check my work, and they only made minor adjustments (to the cap and pass-thru shield). I would have thought their camera would have seen any problems, but their inspection said the cermaic liner was simply older and ideally relined.

Is this 92F too warm? The rest of the walls facing the chimney read 80F or so.

JP

 

[begreen]

The chimney sounds like it needs a full, insulated liner. If there is wood in contact with it, pyrolysis can be taking place.

 

[John Lehet]

My old stove, a Jotul, sent so much heat up the chimney that our steel liner within clay brick chimney was definitely warm to the touch where it went through the bedroom. I guess I probably should have worried about that more, instead of appreciating that it was heating the bedroom a bit.
The new stove, Progress Hybrid, is sending a lot less heat up the chimney, and it is never warm anymore. I touch it often to see if it ever warms up with the new stove, but it does not get warm.

 

[vap0rtranz]

The chimney sounds like it needs a full, insulated liner. If there is wood in contact with it, pyrolysis can be taking place.

I forgot to say that there is a insulation. There's a pour-in insulation between the old ceramic and the new steel. I actually didn't do that and hired a chimney guy to do the pour in. I tried installing a rigid insulation myself but there wasn't enough room and I gave up on shoving it in.

It sounds like I should call that contractor back about this hot spot ...

 

[begreen]

If they didn't put spacers on the liner at regular intervals to keep it centered, the liner may be pressing up against the chimney interior.

 

[mellow]

Here is an excuse to buy a new toy, get a good IR camera so you can see exactly what is going on.

 

[begreen]

I am considering an inexpensive thermal camera attachment for my phone now that FLiR has competition.