Interesting observation - Stove Top Temp vs. Flue Gas Temp

[lbcynya]

Hello All:

My first successful year of burning is almost over... Cleaned the chimney for the first time about a month ago and got about the equivelent of a pop bottle cap full of creosote! Love that double-wall from stove to the chimney cap... Discoloration, but not build up on cap, either. If I sound surprised it's because the wood I have been burning is less than 1 year old oak and cherry (not dry enough in my opinion)...

ANYWAY, before I hijack my own post..., I finally took the plunge and drilled a hole in my double-wall black pipe for a flue gas probe. I have been using a stovetop thermometer all year and it was useful, but I didn't think I was getting the whole picture. My little stove likes to run hot (700-800 degrees to maintain robust secondary)(I know, I know - probably why my chimney is soo clean)(all out of a 1+ cubic foot firebox) and I thought my flue temps would be on the high side as well. I was WRONG. Surprisingly, my flue gas temps and my stove top temps are much closer than I anticipated. The flue probe reacts faster, but they even out over time and the flue gas temp hovers between 600-700 degrees and my stove top temp ranges from 700-800 degrees. Granted both thermometers have a pretty wide margin of error, I am intrigued that the flue temps are, for the most part, lower than the stove top temperatures after everything levels out and the damper is 90% closed (based on the available adjustment).

Are my temperature differences atypical? I expected my flue gas temps to be a least a 100 or more degrees hotter. What ratio for your setup?

 

[Gunner]

After leveling off and "cruising" my probe in the doublewall is 200* less than the stovetop.

 

[Corey]

I would take that as a sign of a good, efficient burn. You are putting maximum heat into the firebox where you can use it, and (ideally) only enough heat into the flue gases to create the draft you need.

Corey

 

[begreen]

That's what I'm seeing - flue temps about 200 deg. less than the stove surface temps. My flue temp rarely gets above 450.

 

[RonB]

The majority of us have the magnetic temp gauge. I put mine on the flue. How does the internal probe type temp gauge compare to the magnetic gauge at the same flue height? Could someone who has both types read these and report their findings? Thanks, Ron B

 

[begreen]

I'd like to, but our pipe is now double-wall.

 

[stoveguy2esw]

depemds on where you position the probe in the flue,on my catalytic unit i had a condar probe catalytic thermometer installed in its position right on top of the cat , i also had one installed in the flue pipe (single wall into a ss lined masonary flue) i routinely observed cat temps and flue temps being relatively identical while stove top temp was usually 300-350 degrees lower example: average burn temp i ran my cat was usually 800 F ( i didnt need to push it) flue temps usually right there with it , stove top temps usually ran about 450-500F this will not be indicitive of readings from a non cat unit. the unit i have is designed as a convective primary, where noncats are usually radient primary.