Stack temps at start and exit of chimney???

[Swedishchef]

Hey guys

Just curious: has anybody ever compared stack temps on various chimney setups?? Measure gas temps in stove pipe and compare to the exit temps at the top of a chimney for various setups? I know there are several factors but considering chimneys are well insulated, I presume heat loss during the travel would be fairly minimal even in the coldest weather or if you have 2 X 45s to get to the chimney or if it's straight to the top.

Thanks...

ANdrew

 

[begreen]

Oddly enough I just did this today. 485ºF in the pipe, ~300º at the cap. About 19' total of pipe, double-wall connector to classA with about 7 ft exposed outdoors. Outside temp was 43ºF. There are a pair of 45's at the stove for an offset, then straight up.

 

[sesmith]

Yea, me too. My neighbors must think I'm nuts standing on my roof in a snow storm measuring chimney temps and air flow. I've used the method in this old article to estimated efficiency of the stove. It provides a bench mark to see the effect of changes made. Recently I fabricated and added on a catalytic combustor to an older stove. Checking the results today.

http://books.google.com/books?id=kQ...esnum=2&ved=0CBoQ6AEwAQ#v=onepage&q=measuring wood stove efficiency&f=false

(You'll probably have to cut and paste the link into you're browser to get it to work. Can't seem to get the whole thing to show up as a link.)

 

[laynes69]

I have tried in the past to figure ours out. I do know when I had the barometric damper installed on our flue, the top of the chimney read 85*. That was a hot fire with a 32' exterior masonry chimney with a 5.5" rigid liner insulated with vermiculite. At the furnace was around 200* external. Since I have now eliminated the baro, I could hold my hand in the top for a few seconds but thats it, I didnt have the IR that time. It made quite a difference. We have a run of about 40' from our furnace to the top of the chimney with 3 90's. Its rare to see our flue temps go above 250* externally. I'm not positive but I think the reason why we see vapor most of the time is the lower flue temps.