No way to monitor flue temps, is it necessary?

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Alexander L

Member
Oct 31, 2014
75
SoCal Desert
I know hindsight is 20/20 but why did you put your thimble so low? Even with a rear exhaust stove you could have elbowed up and out. Now you're kinda stuck if you ever change stoves for some reason.

Well, I didn't have much wall to work with... short walls. Mostly t&g roof. If I ever have to change this stove out, the new stove will go against the wall in front of the window and vent through the roof... where begreen suggested a while back :)

I was almost to the point of just relocating it to that spot... but I've already done so much work. Though... I enjoy the work.

See... short walls
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HomeinPA

Minister of Fire
Jan 4, 2018
510
Central PA
Well, I didn't have much wall to work with... short walls. Mostly t&g roof. If I ever have to change this stove out, the new stove will go against the wall in front of the window and vent through the roof... where begreen suggested a while back :)

I was almost to the point of just relocating it to that spot... but I've already done so much work. Though... I enjoy the work.

See... short walls
Ah hah....it becomes much clearer now.
 

xman23

Minister of Fire
Oct 7, 2008
2,597
Lackawaxen PA
Actually you don't need a thermometer at all. That said I and most have one, on the stove top. With the glass door front, you see exactly how the fire is burning. The stove top is only inches away from the chimney. So my chimney is the same temp as my stove top.

Only a chimney cleaning will tell you how well your burning. Do that after a month or so.
 
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firefighterjake

Minister of Fire
Jul 22, 2008
19,588
Unity/Bangor, Maine
I really like my flue thermometer . . . to be honest I use it far more often than my stove top thermometer.
 
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MisterFixIT

Member
Mar 10, 2016
61
Western Great Basin, USA
Personally I like having both the flue and stove top temp. They give totally different information. I have watched a few hundred burns with the current setup. The Auberins K Thermocouples are great. Mine are a few inches away from each other and they have their own separate story to tell.

The flue pipe will spike early on in the burn which is a good indication I need to quench off the air which will cause the flue temp to crater.
The stove top will spike in the middle of the burn.

I also run both the ChimGuard magnetic pipe sensor and the Inferno stove top. The bi-metal magnetic are good back up but they lag the digital reading off the K-Thermocouple horribly. They lag really bad on the way back down. No comparison.

I like keeping the flue/pipe temp 450 max
I like keeping the stove top temp around 600-650.

Variable fan control based on stove top temperature:
https://www.hearth.com/talk/threads/wood-stove-automation-using-the-raspberry-pi.166145
 

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Dobish

Minister of Fire
Oct 26, 2015
2,038
Golden CO
I really like my flue thermometer . . . to be honest I use it far more often than my stove top thermometer.

yep. i never bother with the stove top. if the ecofan is running, its hot enough. if my flue temps are too high, i'll control it. Cat temp is great too... last night i sat there cursing my load, since cat temps wouldn't get up higher than 750...
 

3fordasho

Minister of Fire
Jul 20, 2007
1,036
South Central Minnesota
I'm finding it kind of odd that anyone who is in the business of making and/or selling wood burning stuff, would recommend against a flue temp thermometer. Even if it is closer to the stove than they think is optimal.


I know why, the condor probe thermometer has the coil right behind the dial and the correct reading depends on a certain amount of heat transfer from the solid probe and some through the two layers of double wall pipe. Use it too close to the stove or as I found out, in a telescoping section of double wall pipe (4 layers, not 2) is does not read correctly. I also found it slow to respond, and not much better than a magnetic surface thermometer. Tel-tru big green egg thermometer replacement much better - its coil that actuates the pointer is actually inside the probe, inside the flue pipe where the heat is!
 

begreen

Mooderator
Staff member
Nov 18, 2005
102,606
South Puget Sound, WA
Yes, it will read a bit high if too close, but that is not terrible. I think the Tel-tru big green egg thermometer is great quality. I like them, but it only reads up to 1000º. Flue gas temps can get higher than that. How did you secure the Tel-tru to the stove pipe?
 

3fordasho

Minister of Fire
Jul 20, 2007
1,036
South Central Minnesota
Yes, it will read a bit high if too close, but that is not terrible. I think the Tel-tru big green egg thermometer is great quality. I like them, but it only reads up to 1000º. Flue gas temps can get higher than that. How did you secure the Tel-tru to the stove pipe?

I take a miniature brass hose barb to 1/8" male pipe thread, drill out the center hole to fit probe diameter, then drill the double wall so the pipe thread will thread in- I don't think I actually used a pipe tap, just picked a diameter the pipe thread will thread into as the double wall is pretty thin stuff. Ash will build up on the probe so it won't always pull out from the brass fitting, in that case just unthread the brass fitting from the connector pipe. As far as the 1000f, the only time I've hit that is on a Fireview that has a bypass = bypass open on that stove allows flames a direct shot up the pipe. On a Progress Hybrid, 30NC, and two different Drolet Tundra installs I've never come close to the 1000F. The time or two I did peg the 1000f on the Fireview, the thermometer was able to be re-calibrated by loosening the nut on the back side of the dial, sticking the probe in boiling water and setting the dial to 212f.

Nothing really wrong with the Condor product, it just didn't work in my situation.

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