Warm chimney blocks

[ikessky]

How warm are the outer blocks of a chimney supposed to get?

 

[RonB]

Ideally, they should be quite cold. This would mean that the liner is insulated and the blocks aren't able to draw heat away from the liner. Prior to getting my masonry chimney relined, on a cold winter's day you could put your bare hand on the chimney outdoors and feel warmth.

 

[ikessky]

Cool, I'm not going to worry about it then. I have an interior chimney that goes up from the basement and is enclosed in a closet in my bathroom. The blocks in the basement are slightly warm, but not even close to alarming. With 300 degree temps going up the flue, I guess I shouldn't have been surprise that the block might get a little warm. I have a SS liner inside the existing clay flue, but didn't insulate because I didn't think I had enough room. I'm wondering now if I should maybe use the pour in stuff and fill any spaces that I can. I'm sure the liner is touching the clay in some spots as it was a tight fit.

 

[ikessky]

I think I see what is happening here. Last night I happened to lean against one of the walls that surrounds the masonry chimney. It felt slightly warm kind of like my floors do right now with the radiant heat in the basement. This got me thinking on what is happening with the heating of my house. It would seem to me that the radiant heat coming off the stove, stove pipe, and duct work in the furnace room is rising and finding the path of least resistance which would be the gap between the floor and chimney where it passes upstairs. The warm air from the stove fills this area, but can't get out through the ceiling of the chase because of the insulation above it, so it is basically trapped in there and ends up dissipating through the walls. I think what I will do is cut a few vents into this chase and extract some of that heat back into the house where it is usable. It could be going into a hallway, bedroom, and bathroom rather than just sitting there.

 

[meathead]

Having a warm interior masonry chimney 'aint a bad thing - Once warm it will disperse heat fairly evenly and hold heat for a long tiem (depending on what kind of masonry). I wouldn't work too hard to solve what doesn't sound like a problem. If it were an exterior chimney - different story. Then you're loosing that heat to the outdoors.

 

[peakbagger]

I used to burn with a fisher "moma bear" woodstove which wasnt really efficient. After a day of burning, my chimney in the floor above would be nice and warm and would radiate heat most of the night. When I switched to my rebuilt VC defiant, the drop in temp of the chimney was very noticable. I can run it and/or my wood boiler for days and the chimney doesnt get anywhere near as warm. Granted I miss the heat mass of the chimney, but I expect the majority of the heat went up the stack. Note, that with either set up, I get little or no creosote.