Flue temps seem high compared to others

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roberth42

roberth42

Member
May 12, 2010
73
Tres-St-Redempteur, Quebec
I have read several times on here where people are getting stove top temps around 650 or higher and flue temps about 450. I cannot seem to get this to happen in my setup.

My setup like 600 or higher!!
I have double wall pipe with a probe thermometer about 18" up from the stove. Am I losing too much heat up the chimney? Can I change something to get lower flue temps? This morning we had the stove loaded and the flue temp was at about 800 and I looked outside and had brown smoke coming from the stack. Is that just burning of some of the residue/creosote?
Here are some photos of my stove with the probe thermometer.
I get great heat from the stove but figure I could get longer burns if I can get lower flue temps. I'm lucky if I can get 5 hours between reloads with hot coals.
Any help would be appreciated.
 

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I think your getting external and internal pipe temps mixed up. 600 internal temps sounds ok once the fire settles in and could peak over 1000 on a fresh load. An external thermometer would read about half those temps on single wall pipe.
 
Todd said:
I think your getting external and internal pipe temps mixed up. 600 internal temps sounds ok once the fire settles in and could peak over 1000 on a fresh load. An external thermometer would read about half those temps on single wall pipe.
Click to expand...

I must be! So what I'm seeing is normal. :)
So on a fresh load 1000 is normal too? How long can it stay at 1000?
Thanks for the replies.
 
roberth42 said:
Todd said:
I think your getting external and internal pipe temps mixed up. 600 internal temps sounds ok once the fire settles in and could peak over 1000 on a fresh load. An external thermometer would read about half those temps on single wall pipe.
Click to expand...

I must be! So what I'm seeing is normal. :)
So on a fresh load 1000 is normal too? How long can it stay at 1000?
Thanks for the replies.
Click to expand...

Many here with similar probes see the same temps. I don't think they are the most accurate and they seem to read a couple hundred degrees high on the higher end of things. I still think they are a good tool to get a general idea of whats going on. I can't speak for your stove but when I used a probe on my pipe I use to see 800-1000 on a fresh load for about 30-45 minutes before dropping down to 500-700.
 
Todd said:
Many here with similar probes see the same temps. I don't think they are the most accurate and they seem to read a couple hundred degrees high on the higher end of things. I still think they are a good tool to get a general idea of whats going on. I can't speak for your stove but when I used a probe on my pipe I use to see 800-1000 on a fresh load for about 30-45 minutes before dropping down to 500-700.
Click to expand...

+1 Pen has a couple of very informative threads where he carefully tested the Condar probes and found they read high. It's very good to be careful and keep an eye on things, but be aware that those things aren't completely accurate, and can cause needless concern.

EDIT: Pen's tests showed that the probe's readings are consistent, though high. In other words, once you get used to them they give you a consistent idea of what's going on. Just don't put a lot of stock in the actual numbers.
 
(Curious) George said:
Pen's tests showed that the probe's readings are consistent, though high. In other words, once you get used to them they give you a consistent idea of what's going on. Just don't put a lot of stock in the actual numbers.
Click to expand...

That's the take home message. Get used to what the stove is doing at a given point on your thermometer and don't worry how close the thermometer is to the exact temperature. If you're burning clean and your house is warm, you have to be pretty close to ideal. And a 5 hour burn is not bad at all for a sub-2 cu.ft. firebox.
 
Practice will make perfect. There's not that much wood in there. You can load it up to the top of the bricks. Fire looks smallish, shoulder season sized, which may need more air.

How closed is the air control when that reading was taken? Try closing it down more and see it that helps lower the flue temps.
 
BeGreen said:
Practice will make perfect. There's not that much wood in there. You can load it up to the top of the bricks. Fire looks smallish, shoulder season sized, which may need more air.

How closed is the air control when that reading was taken? Try closing it down more and see it that helps lower the flue temps.
Click to expand...

I only put in 2 splits just to maintain the house temp. If I load her upto the top of firebricks it will heat us out of the house even with outside temps 5*F.
The air control was completely closed when the picture was taken.
 
My probe reads 700-1200 regulary. I had been concered too much heat was going to up the chimney, but my stop top is always at 500-600 during this time periode. If I kept anymore heat from going up the chimney i'd be a little uncomfartable as my stove top temps would shirly be at 700-800.
I think your perefctly fine.
 
On double wall, you'll be fine so long as it doesn't get much past 1k degrees. If it were single wall and that height above the stove, I'd say 1200 based on what I've seen.

pen
 
My stove top follows my flue. 75* less (+or-) with the blower on. Keep in mind that I have a downdraft stove and a LOT of heat is in the back of the stove-not the top. I'm burning mostly <20% MC ash, red maple, and locust
(all internal probe temps.)
600*-700* is pretty normal for me on a low clean burn. Depending on how I do with coal bed, fuel size, etc..., I might sit at 800* for an hour.
500* within an hour or two of loading up full is bad news. I've got to run hotter.

And I have checked my condar probe with a thermocouple and found them to be very close.
 
I agree with John. Flue pipe thermos were your best tool when all you saw when you looked at the front of the stove was a piece of cast iron between you and the fire. My stoves in the fireplace have had glass in the doors since 1985 and have never had flue pipe thermos.
 
I don't necessarily agree with John. Flue temps can be a good guide if you really want to fine tune your burns and can also tell you a lot about your draft. But for most people it's prolly not nessasary.
 
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