Surface Temp of DW SP--How High?

[graycatman]

I'm wondering how hot people let the surface temp of their DW stovepipe get before turning down the air. Although during a burn I like to keep it around 220-240 at 20" from the stovetop, on startup and new load I would like to let it go higher. And sometimes if burning a good load of great wood, I would like to let it settle in at 260-270 (I have a pretty tall chimney and feel I should run a little hotter than someone with a more average size chimney.)

Last season there were a few discussions about whether surface temp of DW is meaningless or "only relative". Some members with both probe and IR guns were also generous enough to take readings on both, at the same time and height. However, the results indicated probe temps of between something less than 2x to something more than 3x the surface temps. So a surface temp of 250 could be a flue temp of somewhere between 475 and 800. I don't feel I need to know the flue temp to the degree, or even within 100 degrees (and prefer not to put a probe in). Just need to know it's hot enough to discourage creosote formation, and not so hot that I'm pushing the envelope on the pipe. I feel that if i'm above 200 I'm OK on the low end. Just wondering about the high end.

Many thanks.

 

[Backwoods Savage]

Welcome to the forum graycatman.

We do not have the same stove but most are pretty darned close on what the flue runs.

On reloads we take the flue temperature up to 500 (single wall, magnetic thermometer) and sometimes have gone higher. After we dial the draft down our flue will generally be in the 300-350 range. I hope this helps.

 

[graycatman]

Thanks, Dennis. Just so I'm clear, your thermometer is measuring the surface temp of your single wall pipe? If so, according to many posts here, that would give you flue temps of 750-1000 on startup, and flue temps in the 500-600 range once settled. That's good to know, although i'm still wondering about high-end surface temps on my DW stovepipe.

 

[WES999]

I really don't think you will get any meaningful temp info from the surface of DW pipe.

I have a digital thermocouple probe inside my Simson DW stove pipe. Today when I started up the stove the internal temp was almost 1000 °F, and the outside surface temp (measured with a digital surface probe) was only about 150 °F .

Now there are many variables and each install is different but you may be overheating your flue if you are seeing 270 °F on the surface.

 

[graycatman]

Thanks, Wes. I am curious: is your pipe vertical directly above the stove; how far above the stove are you measuring; when you have a stable stovetop temp of x what is your pipe surface temp?

I'm just trying to sort out various info I've read here. For example, see https://www.hearth.com/econtent/index.php/forums/viewthread/46956/.

But I completely accept your point that the only truly accurate way to know flue temps with DW SP is to use a probe (setting aside any inaccuracies of the probes themselves.)

 

[WES999]

See post #2 for a pic of my setup.

https://www.hearth.com/econtent/index.php/forums/viewthread/45419/

When I start up with a cold stove I use a fair amount of pallet wood, once it starts to catch the flue temp will rise quickly, when the temp hits about 900 °F, the alarm will sound and I will cut back the air. The very fast heating of the inside probably does not give the outside a chance to warm up, causing a large difference.

My case may be a bit extreme but it illustrates the difference between the inside and outside of DW pipe.
IMO a probe is the only way to go with DW pipe.

 

[begreen]

I really don't think you will get any meaningful temp info from the surface of DW pipe.

I have a digital thermocouple probe inside my Simson DW stove pipe. Today when I started up the stove the internal temp was almost 1000 °F, and the outside surface temp (measured with a digital surface probe) was only about 150 °F .

Now there are many variables and each install is different but you may be overheating your flue if you are seeing 270 °F on the surface.

Agreed. I found a much more dramatic decline of surface temps just inches apart. Double wall pipe needs a probe thermometer for accurate reading of flue gas temps. Some double wall is vented, which I expect would make readings on the surface irrelevant.