Stove pipe temperature (over firing)

Crimson Blaze

New Member
Sep 30, 2017
12
Peoria Il
Hi everyone!
I have a small Morso 1440 wood burning stove.
Our manual says that its maximum temperature is 750 degrees when measures on the stove pipe at 20 cm above the stove. Above 750 in that spot is considered over firing.
However, we have a double walled stove pipe, so we can't get an accurate temperature on the pipe.
Does anyone know what is an average comparison?
We could use for example on avg stove temp of 850 = single walled pipe temp of 750
or on avg single wall temp of 750 = double walled temp of 700.
Thanks!
 

begreen

Mooderator
Staff member
Nov 18, 2005
84,307
South Puget Sound, WA
I don't buy that unless they are talking about using a probe thermometer on double-wall stove pipe. Surface thermometer reading on a single-wall pipe can indicate only about half the interior flue gas temp. In the case mentioned the pipe would be glowing red with a 1500º interior temp. For single-wall pipe a safer temp would be 350-400F on the surface thermometer. For double-wall try to keep it below 700ºF and you should be fine. Your probe thermometer is actually giving a more accurate reading. Surface temps on a double-wall pipe are not very helpful.
 

enigmablaze

Member
Oct 30, 2015
191
illinois
I don't buy that unless they are talking about using a probe thermometer on double-wall stove pipe. Surface thermometer reading on a single-wall pipe can indicate only about half the interior flue gas temp. In the case mentioned the pipe would be glowing red with a 1500º interior temp. For single-wall pipe a safer temp would be 350-400F on the surface thermometer. For double-wall try to keep it below 700ºF and you should be fine. Your probe thermometer is actually giving a more accurate reading. Surface temps on a double-wall pipe are not very helpful.
This stove has no probe thermometer on the double wall pipe, only a stovetop thermometer with the "400-650" zone highlighted on it. So if the stovetop says 600 degrees, what is a good approximation for the stovepipe temperature? (wife of OP;lol).
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
22,163
central pa
This stove has no probe thermometer on the double wall pipe, only a stovetop thermometer with the "400-650" zone highlighted on it. So if the stovetop says 600 degrees, what is a good approximation for the stovepipe temperature? (wife of OP;lol).
With a surface thermometer on double wall your reading dont mean much at all. You need a probe if you want to measure pipe temp on doublewall
 

Woody Stover

Minister of Fire
Dec 25, 2010
12,159
Southern IN
When ramping up a new load, I look into the box to watch the amount of flame entering the flue exit. As more wood gets burning, I don't want the air control on the stove open so far that roaring flame is being pulled into the flue exit. I want active but slower-moving flame dancing around and into the flue exit. Keep your fire under control and you shouldn't be exceeding safe temps in your stove or chimney. Listen to the expansion clicks and pops of the stove and pipe. Quiet noises mean you probably aren't pouring to much flame into the flue exit area of the stove, and into the chimney, early in the burn with a cooler stove. But once the stove stabilizes at high temps, noises may be fairly quiet but temps can still be too high. You can install a probe if you are still unsure.
 

Squirrel

Burning Hunk
Sep 23, 2014
156
Ontario
I have a morso 1410 with double wall pipe and a probe thermometer at 20cm above the stove, put there by the installer (Nice guy). I also have a stove top thermometer used on a previous stove.
These two points are so close together that there is very little difference in temperatures once the stove is hot and cruising. I consider I'm being really efficient if I have the stove top slightly hotter than the pipe.
On first lighting or reloading the probe thermometer will climb a lot faster than the stove top.
During cold weather my stove top runs around 650f with the occasional oops! to 750-800.
 
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Poindexter

Minister of Fire
Jun 28, 2014
2,251
Fairbanks, Alaska
I upgraded to flue gas probe thermometer through my double wall pipe, and ran my old magnetic beside it for a couple weeks.

On my install when the stove was running sready for at least half an hour the magnetic would settle in at about half of of what the flue gas probe was reading.

As the fire went out, the magnetic would lag behind the gas probe in dropping.

On a cold start i had the flue gas probe up to 1000 before the magnetic got to 200, and that was when i stopped running the magnetic on double wall - when i needed it the most, it was at its least accurate.
 
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enigmablaze

Member
Oct 30, 2015
191
illinois
With a surface thermometer on double wall your reading dont mean much at all. You need a probe if you want to measure pipe temp on doublewall
Right, we have NO thermometer on the double wall, only the stovetop thermometer on the stovetop. We're trying to figure out what those stovetop temps would equal in the stovepipe at the time.
 

begreen

Mooderator
Staff member
Nov 18, 2005
84,307
South Puget Sound, WA
Either get a probe thermometer and install it on the double-wall pipe or just go by the stove top temps. Keep the stove top below 750F and you should be fine.
 

enigmablaze

Member
Oct 30, 2015
191
illinois
I have a morso 1410 with double wall pipe and a probe thermometer at 20cm above the stove, put there by the installer (Nice guy). I also have a stove top thermometer used on a previous stove.
These two points are so close together that there is very little difference in temperatures once the stove is hot and cruising. I consider I'm being really efficient if I have the stove top slightly hotter than the pipe.
On first lighting or reloading the probe thermometer will climb a lot faster than the stove top.
During cold weather my stove top runs around 650f with the occasional oops! to 750-800.
Thanks so much Squirrel, That is really what I was looking for. Since we can't get a good temperature reading on the pipe (without installing a probe) And since tho only temperature limit that is provided was for the pipe, I was trying to get a idea what temp I should look for on top of the stove instead.

So it sounds like you are saying the temperature in the pipe should be about the same as on top of the stove, once the stove is up to temp. Perhaps there would be a difference of 25-50 degrees?

Thanks again everyone!
 

begreen

Mooderator
Staff member
Nov 18, 2005
84,307
South Puget Sound, WA
The differential will vary somewhat with the stove and the the flue draft strength. If things are working right then a stovetop temp a bit below the flue gas temp is good. Our stove runs about 100º below once the air has been turned down.
 

Woody Stover

Minister of Fire
Dec 25, 2010
12,159
Southern IN
Right, we have NO thermometer on the double wall, only the stovetop thermometer on the stovetop. We're trying to figure out what those stovetop temps would equal in the stovepipe at the time.
As Poindexter said above, stove temp may be closer or farther from flue gas temp depending on what phase of the burn you are in. Sounds like a probe is the answer for you as it will remove all doubt.