# Double Wall Stove Pipe Temps



## Crash11 (Nov 30, 2009)

What would you guys say is a good temperature for the outside surface of double wall stove pipe during an extended burn?  All I have right now is a surface mount thermometer.  Next year when I disconnect the pipe for its annual cleaning I plan to install a probe style thermometer, but for now surface temp is all I have.  I've been shooting for 350-400 F.  That sound decent?


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## pgmr (Nov 30, 2009)

Why wait?  Drill the small hole (actually might be two holes - larger for outside bushing, smaller for probe into inner pipe), insert the bushing into the outer pipe, put probe thermometer through bushing and into inner pipe - done.  You do need to remember to remove the probe prior to cleaning if you're able to clean from top down (but it sounds like you can't in your situation).


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## Jags (Nov 30, 2009)

The outside temp of a double wall pipe is just almost next to meaningless.  Heck the gentle breeze of a ceiling fan is enough to throw the temps off far enough to be completely disregarded.  Get the probe dude.


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## Highbeam (Nov 30, 2009)

I recently installed my probe meter into my double wall pipe. It was super duper easy and did not require removing the double wall. 

You can hold your hand against the outside of my double wall during all but the most extended 1000 degree flue temp sessions.


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## firefighterjake (Nov 30, 2009)

PGMR took the words right out of my mouth . . . well my mind. 

As I was reading this thread I thought "Why wait?" 

As mentioned surface temps of the double wall pipe really don't give you very good readings . . . and installing a probe thermometer is so simple even a dumb Maine firefighter can install one in 15 minutes (and it should be mentioned that the first 5 minutes of this project was the dumb firefighter reading and then re-reading the instructions because he couldn't believe it was so easy and another 5 minutes was spent looking in his drill box for the right size drill bits and making a mental note to some day organize those bits.)  

Trust me on this . . . get a probe thermometer (anticipating your next possible question . . . Condar . . . I bought a Condar thermometer on-line) . . . you'll be happy and pleasantly surprised how "super duper easy" it is to install to quote Highbeam.


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## oldAGE (Dec 4, 2009)

For what it's worth, if you didn't insert the probe yet, I think that around 18" above the stove on double walled (I have Duravent), your range seems high.  OK, bring on the flaming.
With my stove sitting squarely around 550, my pipe is around 225.


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## oldAGE (Dec 4, 2009)

For what it's worth, if you didn't insert the probe yet, I think that around 18" above the stove on double walled (I have Duravent), your range seems high.  OK, bring on the flaming.
With my stove sitting squarely around 550, my pipe is around 225.
AGE


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## DAKSY (Dec 4, 2009)

oldAGE said:
			
		

> For what it's worth, if you didn't insert the probe yet, I think that around 18" above the stove on double walled (I have Duravent), your range seems high.  OK, bring on the flaming.
> With my stove sitting squarely around 550, my pipe is around 225.
> AGE



Is there an echo in here?


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## begreen (Dec 4, 2009)

The reading is going to be bogus and strictly relative with a surface thermometer on the double-wall pipe. For one, it is going to vary dramatically based on the distance from the flue collar. 

For example, current readings: stove top 590 °F , Probe reading at ~24" above the stove flue collar = 405 °F , IR thermometer reading of the flue surface next to probe = 210 °F , at 18" the same reads 245 °F .


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## oldAGE (Dec 5, 2009)

DAKSY  DAKSY

Yes!  Yes!

A little ISP problem  

AGE


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## oldAGE (Dec 5, 2009)

BeGreen said:
			
		

> The reading is going to be bogus and strictly relative with a surface thermometer on the double-wall pipe. For one, it is going to vary dramatically based on the distance from the flue collar.
> 
> For example, current readings: stove top 590 °F , Probe reading at ~24" above the stove flue collar = 405 °F , IR thermometer reading of surface next to probe = 210 °F , at 18" the same reads 245 °F .



So BeGreen?  Why do you call it bogus?  You are absolutely correct on using the term "relative."

Isn't that the point?  A relative reference to reflect the fact that your fire is burning hot enough but not too hot?  Assume you have a load that has your stove humming along at 575 and secondary burn.  Would you really tweak the air or damper (whatever control one has) to get that down to 550 based on your flue gas temp?  Then, you refuel when necessary.  Don't most of us learn the behavior of our stoves so that we know what we need to do but we don't micro manage the fires.... "Oh, my flue gas is 50 degrees too hot so I have to knock it down a bit."  Yeah, we may see that 575 is a bit too warm so we make a small adjustment.

On my VC Encore and double walled pipe set up, I take my reference at nearly the exact spot -- an inch above a rivet which is nearly 18" above the stove collar.  Depending on fuel and combustion, this spot can be as high has 325+ when I first get my fires going when the griddle is ranging from 400 - 600 with a low coal bed.  As it evens out and the coal bed rises and I engage the damper, the griddle temps range less than 50 degrees and the spot on my pipe is around the "right" relative number.

I don't believe the person who said it all depends on air circulation (like from a fan) or ambient room temperature.  We are talking about relative degrees that are meaningless.  If those conditions affect the pipe temp by more than a degree or two or five, what's the harm?  Do you make sure that your flue gas is 405 and not 410 (overfire?) or 400 (creosote condition)?  And for the person who said they can put their hand on their pipe during a fire, they are not measuring it at the recommended location for any probe.  Using BeGreen's numbers or even mine right now (just measured at 218), I dare you to stick your hand in a pot of boiling water.   

I think every stove, every installation, every room, outdoor conditions (temp, humidity, etc) and each load of wood creates a variable that is not exact.  That's why I believe "relative" works.

So, to the OP,  My VC Encore runs efficiently with the damper on and a good coal bed in 215 - 250 range at 18" above the flue collar.  For a relative relationship, at those temps, my stove is running around 475 - 600.

AGE


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## oldAGE (Dec 5, 2009)

Here's a case to prove what I am trying to say here that happened while I was crafting the above.  As I wrote the above, I check my numbers and refueled.  My wife asked me something and I had a brief conversation.  I then came back and finished the above message, checked my emails, and then went back to my stove and to see how things were since my adding the wood.  For giggles I grabbed my IR and checked the temp at "my stove pipe spot" and it read 278.  "Uh oh, now what!" I thought.  Air is right and my damper is....  Ugh!! disengaged.  When my wife asked me that question, I turned and got distracted and didn't put the damper on after refueling.

My point is the number was high relative to where I know it should be.  Once engaged, and time to settle,  it now sits nicely at 248 with the CAT rumbling.

AGE


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## Highbeam (Dec 5, 2009)

For a guy with name of oldage I would think you should know that there is a difference between touching something that is 200 degrees and putting your hand in boiling water. Before you make such silly comparisons, how about touching your stove pipe that measures 200 on the surface. You will quickly realize that it is not the same thing as putting your hand in boiling water. 200 is pretty cool. 

Relative is one thing but consistently relative by the same factor is quite another. You need to consider that there isn't a linear relationship between surface temp of the doubel wall and interior flue temp. I propose that the outside temp might be near double the interior temp during low fires but when the flue is at 1000 I do not expect 500 on the outside, perhaps much cooler. So you can plot data and make up a curve and then a custom equation for each ambient room temp setting.


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## begreen (Dec 5, 2009)

> So BeGreen?  Why do you call it bogus?  You are absolutely correct on using the term “relative.”



Maybe bogus is too strong a word, perhaps inconsistent would be better. The outside of the double wall pipe is getting heating by both the direct heat coming from the stove top and the heat radiated by the hot flue gases. The point of the flue thermometer is to know the temperature of the flue gases heading up the inside of the pipe. Guessing that from the exterior of the double wall pipe is deceptive because until it reaches stasis, it will continue to rise while the interior flue gas temp may be quite consistent. A probe thermometer takes the guess work out of this and lets you know how hot the flue gases that are heading up the chimney really are. If one is concerned about creosote buildup, that is a helpful figure to have a fairly accurate reading on.


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## pgmr (Dec 5, 2009)




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## oldAGE (Dec 5, 2009)

I don't disagree with the general sentiment of any of these conversations.  As a double walled pipe user, I gave the OP an answer.  I agree that a probe is best for being scientific, no doubt. When I clean my 22ish feet of 8" pipe, I pull out about about two pints volume of "stuff."  In the end, it all works well for me.  For Highbeam, necrosis begins at 112 degrees F.  160 degree F can cause severe burns when measuring exposure in single digit seconds.  Depending on what you do with your hands (highly calloused, etc.), at 200 degrees, you may last a few seconds.  I doubt that anyone can effectively keep their hands on a "200 degree cool" stove pipe to effectively measure it's temperature.  Yes, I am oldage but also oldscientist too.  I like to experiment but I think you are exaggerating what the average person can do. 
AGE


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## Highbeam (Dec 7, 2009)

Just for you age, actually for a gut check for me, I tested your instant death theory this morning when the stove top had cooled to a low 200 temp overnight. Sure as heck, you can absolutely put your fingers and/or hand right on there unless you are some sort of skirt wearing sissy. Leaving it there for long is not something I discussed and certainly would not recommend, maybe that's where we went sideways?

This is the difference between thinkers and doers. Many of us that actually have welded and worked with metal know that you can test for hotness by touching something and won't likely get a damaging burn unless the metal is glowing. If you have a feeling its really hot but not red hot you can lick your finger first and test the sizzle length. You can even place a palm hovering over the metal and, with experience, guess the temp fairly closely.

How about getting a probe meter and preventing the whole discussion? As a scientist you surely know that you don't check the internal temp of your steak by measuring the shell of the barbecue.


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## Jags (Dec 7, 2009)

For a relative measurement of stove temp, I went with the ambient room temp.  Its relative right??

I am not really trying to be a smart azz - well, ok...maybe a little :red: , but my point above is that relative readings don't necessarily give you the REAL measurement you are looking for.  Maybe it is because of latency or some other factor, but if I am looking for flue gas temp, thats what I'm gonna measure.  Its just the way I am.

Something as simple as stove top radiation (which can and does change in a non-linear fashion when compared to flue gas) could change the surface temp of the pipe pretty drastically.


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## oldAGE (Dec 7, 2009)

OK... I'll bite for both of the above posts.
Yes, I like wearing skirts and I never professed to be a real man.
Secondly, you can argue every point until you are blue in the face (and some are silly but some are serious) -- but the question is -- with said Flue Gas Temperature, what do you do with that information?  What does it buy you?  I think examples of numbers and what you do and what they mean would serve a guy like me best.  

I absolutely agree that it's the best, most accurate measurement of what is happening with your stove at any time.  Will never argue the contrary.   

AGE


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## Jags (Dec 7, 2009)

oldAGE said:
			
		

> I absolutely agree that it's the best, most accurate measurement of what is happening with your stove at any time.  Will never argue the contrary.
> 
> AGE



Good, thats all I wanted to hear!

NEXT!

****you DO know that I am just yanking your chain now, right?**** :coolsmile:


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## Crash11 (Jan 5, 2010)

Sorry to resurrect an old thread, but you will all be happy to know I installed a probe thermometer last night.  I was very surprised at how different the temps were.  I left my surface thermometer where it was originally, and compared the two (probe thermometer 18 inches above stove top).  When I was at a stable 600 degrees inside the pipe, the surface was measuring somewhere around 175 degrees.  So basically up until this point I was probably having fires up in the 1000 degree area this whole time.  Yikes.


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## oldAGE (Jan 5, 2010)

And that's why I wrote that your range seemed high for double walled pipe.  My relative bet is that with your double walled temp at 225, your probe will read around 800 and your stove top would read around 550ish.  Again, every stove is different.  That's why it's more art than science but your original numbers seemed too hot.  Mine is based on burning a VC cat EPA stove for nearly 10 years.

So do this purely unscientific test -- get your stove up to what you deem proper operating temp and efficiency.  Record all three temps - stove top, double wall, and probe.  Do this four, seven, 10 times and post.  Just curious to see the variances.  Again, I don't have a probe but I do have an IR and a mechanical stove top.  With the temps at a high of 5 degrees this past weekend, and a mixture of not perfectly seasoned and seasoned oak, my stove ran around 525 - 560 and my double wall read around 216 - 238.

Keep warm and keep burning cleanly.
AGE


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## RustyShackleford (Jan 6, 2010)

Highbeam said:
			
		

> You can hold your hand against the outside of my double wall during all but the most extended 1000 degree flue temp sessions.



Damn, I can't even hold my hand against the outside of my Class A, not for very long at least.
Seriously, it seems like my flue gasses are too hot (I have no probe).   How could that be, if
the cat is engaged and working properly ?


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## pinewoodburner (Jan 6, 2010)

oldAGE said:
			
		

> And that's why I wrote that your range seemed high for double walled pipe. My relative bet is that with your double walled temp at 225, your probe will read around 800 and your stove top would read around 550ish. Again, every stove is different. That's why it's more art than science but your original numbers seemed too hot. Mine is based on burning a VC cat EPA stove for nearly 10 years.
> 
> So do this purely unscientific test -- get your stove up to what you deem proper operating temp and efficiency. Record all three temps - stove top, double wall, and probe. Do this four, seven, 10 times and post. Just curious to see the variances. Again, I don't have a probe but I do have an IR and a mechanical stove top. With the temps at a high of 5 degrees this past weekend, and a mixture of not perfectly seasoned and seasoned oak, my stove ran around 525 - 560 and my double wall read around 216 - 238.
> 
> ...



Every stove and setup is different. My Woodstock exits our the rear for 30 + inches before the T and going up the flue. That part is double walled and I can put my hand on it when it running at its hottest. I have never seen temps over 150 degrees and it is usually like 100 to 110. But this pipe is not getting heated from the stove live a vertical pipe would. I did clean the pipe and the liner after the first season and I had less than a cup of ash that got cleaned out, but that is the cat stove for you


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## woodhound (Jan 7, 2010)

All this talk of IR guns, flue temps, stove temps is giving me a headache.  Seems like some of you take wood burning to the extreme.  It's just a box of rocks you throw wood in,  If your wood is good and dry and heat is comming out it's burning just right for me. Keep it simple and don't worry about it.


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## Jags (Jan 7, 2010)

woodhound said:
			
		

> Seems like some of you take wood burning to the extreme.



If you have come to this site seeking "normality" - you are going to be sadly disappointed. %-P


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## RustyShackleford (Jan 7, 2010)

Jags said:
			
		

> woodhound said:
> 
> 
> 
> ...



You make a good point.  I had been heating with wood for 25 years before I can to this site, and
was shocked at how much people obsess over their wood burning.  I have never had a flue pipe
thermometer, or stove-body thermometer - just the cat thermometer.   But I am also an engineer,
and I just had to pry my fingers away from the keyboard to keep from buying an IR thermometer
recommended in another thread ...

This forum did convince me to replace my aging Dutchwest cat with a Blaze King, and after using the
BK for 2 months, I will forever be grateful !


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## Jags (Jan 7, 2010)

RustyShackleford said:
			
		

> I just had to pry my fingers away from the keyboard to keep from buying an IR thermometer



Resistance is futile.  This action will haunt you in your sleep.


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