Condar Temp Probe vs. The Thermocouple...

[firefighterjake]

I would like to see if there are any differences on double wall pipe in terms of the accuracy since it seems to me that this is where most folks with probe style thermometers would tend to use this vs. going with the simpler and less expensive magnetic style thermometer which could be used on single wall pipe.

My own take . . . I still tend to view my thermometers as only a rough guide . . . and when running my stove tend to keep the temps as close to being in the Goldilocks Zone as possible . . . preferring to keep the temps about halfway in the "just right" zone . . . as I have always figured that the temps could easily be running a bit higher or a bit lower . . . and so far, based on the fact that I have not overfired my stove or chimney . . . and I have not had an excessive amount of creosote I have to say the thermometer is working for me.

That said . . . if a company comes right out and says my product is X degrees accurate . . . when in fact tests show it is not accurate . . . well I have a hard time supporting this product if it is not what it promises and it fails to deliver on that promise . . . and so I continue to follow this thread and Condar's response.

 

[Highbeam]

"But I know in my setup, with the probe 18 inches up the flue I am only running a stove top of about 450 degrees (barely going) and have a flue reading that is just entering the “too hot” zone of about 1000 degrees."

Remember that you can't assume anything based on flue gas temp other than how hot the flue gas is. Your stove's temp is not dependent or directly related to flue temp and we should all have a stove thermometer first, and a flue gas temp meter second. For example, I can have my condar reading 1000 in 15 minutes from a cold start and the stove temp is barely registering on the stove's surface temp meter.

I've been much happier with my new routine of starting a new fire and letting the flue gasses run to a "condar" 1200 and then backing off the primary air to cruise level. It's much harder to snuff the fire when the first burn is that hot and that hot first burn does a great job of burning off any junk from the glass.

 

[jzinckgra]

So if my glass is staying clean, can I assume I am burning and the right temp and minimizing creosote?

 

[mikepinto65]

"But I know in my setup, with the probe 18 inches up the flue I am only running a stove top of about 450 degrees (barely going) and have a flue reading that is just entering the “too hot” zone of about 1000 degrees."

Remember that you can't assume anything based on flue gas temp other than how hot the flue gas is. Your stove's temp is not dependent or directly related to flue temp and we should all have a stove thermometer first, and a flue gas temp meter second. For example, I can have my condar reading 1000 in 15 minutes from a cold start and the stove temp is barely registering on the stove's surface temp meter.

I've been much happier with my new routine of starting a new fire and letting the flue gasses run to a "condar" 1200 and then backing off the primary air to cruise level. It's much harder to snuff the fire when the first burn is that hot and that hot first burn does a great job of burning off any junk from the glass.

+1 Im with you on this one Highbeam

 

[Troutchaser]

Was it this thread that we discussed the end of the probe being placed in the middle of the flue? This is what Condar states you should do and so I pulled mine out of DW pipe about two inches. When I did this, there was a noticeable decline in temp. Approx.
100deg. on a steady 600.

Curious if everyone runs with it flush to the pipe.

 

[JoeyD]

Was it this thread that we discussed the end of the probe being placed in the middle of the flue? This is what Condar states you should do and so I pulled mine out of DW pipe about two inches. When I did this, there was a noticeable decline in temp. Approx.
100deg. on a steady 600.

Curious if everyone runs with it flush to the pipe.

I just pulled mine out about an inch and I'm going to see if it makes a difference. It seems almost impossible to keep my stove within specs which Napoleon says are 250-450 flue temp. Right now my stove seems to like 550 to 600 with my condar.

 

[Highbeam]

Trout: You are doing much more than pulling the probe tip to the middle of the flue. You are also pulling the bimettalic coil inches from teh heat source where it can be influenced by room air. The design of this meter depends on it being a particular distance from the pipe. Cut the tip of the probe off to hit the center of the flue if you choose. You must run it flush to the pipe, especially with double wall.

Joey: Many stove manufacturers assume that your "flue temp" is the temp you get when you stick a magnetic surface meter onto the flue pipe. So you can double the Napolean temps to get flue gas temps of 500 to 900 which falls right in the condar recommended operating range.

 

[Troutchaser]

Thanks highbeam.
I can really just cut the thing off and not screw it up (any more than it might already be screwed up from factory)?

 

[Todd]

Thanks highbeam.
I can really just cut the thing off and not screw it up (any more than it might already be screwed up from factory)?

I cut mine but I don't know if it made any difference in temps.

 

[Highbeam]

If Todd hadn't already made the cut then I would worry about the probe being full of fluid or something fancy but apparently the probe is only a steel rod meant to conduct heat to the coil. I don't plan to cut mine. I have determined that it doesn't really matter what the actual temperature indication reads so long as I know the temps on the factory condar which correspond to 400 and 1000 which thanks to the thermocouple work provided on this site we do know these points as 500 and 1200 degrees "condar". Yes I invented the condar units, not celsius or F. We all can agree that the basic meter design is dependable and rugged with repeatable performance. I don't want to loose the repeatable performance by cutting or modifying it.

What's the saying?.... It's precise but not accurate.

 

[pen]

Here is the response from Tim

Yes, I did receive it and have done multiple temp tests with it through last Friday.



To sum up my test using our Thermolyne Tube Furnace (similar to this example)…

…with the probe inserted into the right side and a long thermocouple probe inserted in from the left side to be in close proximity to the probe tip. (The furnace has its own thermocouple control and temp readout to compare as well.)



THERMOCOUPLES 3-39 PROBE

14000F 1410F

1200F 1200F

800F 720F

750F 700F

650F 600F

400F 400F



I did other test conditions with similar mid-range temps to prove/disprove the effects of air-movement around the furnace. I discovered there are some differences. In a confined area where the heated room builds up, the temp will read higher. Likewise, if there is an open area with air movement (like a ceiling fan), the temp will read lower. So, as you see our controlled lab results are fairly close.



I had the occasion to talk with a couple of woodstove OEM’s about temp readings and asked them about flue-gas temps and whether the use of an IR meter is accurate when measuring the surface of the flue pipe; they said absolutely not. Of course that makes sense if measuring a double-wall pipe, but they said even single-wall pipe flue-gas must be measured inside. They testified the gas swirls and you can see different temps depending on where the measurement is being taken; your test confirmed that by moving the probe just a little higher than prescribed.



So, I’m not sure we’ve come to a good conclusion or not, but these are the anecdotal facts with a dose of controlled testing. Both OEM’s confirmed that they see most consumers trying to operate their stoves at too hot a temp or just below the max. There is some talk in the industry where consideration is being given to communicate to the consumer regarding operating temps not as an F or C number, but in an OPERATING ZONE with no numbers.



More to come as those ideas develop.



Thanks for your patience and business.



Regards,

Tim

In general, this means that according to Tim, the reason Wes and I are having high readings are because of the high ambient temps in the area of our stove.

Additionally, when I had the probe installed 18 inches up from my stove top, I had to run my stove top at about 450 during a "cruise" (ignoring hotter than normal startup conditions) to maintain temps in the normal range on this thermometer. This is far colder than I normally run my stove top. At these temps, the stove is in suffocation mode IMO and some visible smoke is seen from the chimney.

My probe gives me temperature readings that are "believable" at a height of 28 inches above my stove top. In other words, a normal burn where my stove may cruise at 600 to 650 stove top reads at or below their 900 degree mark on the probe. My question is, are the more reasonable readings the result of a cooler ambient location or the result of truly cooler flue temps?

My thoughts:

1. In all, I am very happy with the performance of my probe now that I have it installed 28 inches above my stove top.
2. I disagree with the idea that I am running my stove too hard and feel that their estimates are too conservative.
3. Essentially, I think that the directions on the package are misleading for installation.
4. I feel that the claim on the package for the probe reading roughly 50% higher than single wall pipe values is bunk. Rather, at each location I consistently get values that read 3x higher.
5. If single wall surface pipe temps are so inconsistent, how can ANY brand magnetic stove pipe thermometer have any value?


I have shared these thoughts with Tim as well, I will keep everyone posted of any response.

pen

 

[Pagey]

Thanks for the follow through, Pen. This has been a most interesting discussion to follow.

 

[Todd]

Thanks for the update Pen. I don't really see how their little machine can simulate the differences in readings of single wall verses double wall. There is no way their probe is accurate at higher temps in single wall with all that radiant heat coming off the pipe.

 

[pen]

Thanks for the update Pen. I don't really see how their little machine can simulate the differences in readings of single wall verses double wall. There is no way their probe is accurate at higher temps in single wall with all that radiant heat coming off the pipe.

My thoughts exactly, I asked how about how the machine takes that variable into account in my most recent email

in fact, here is my response:

Thank you so much for getting back to me.

I can't argue with your test and the probes accuracy for that furnace. My only question is how close to true "in the field" conditions it can be? For example, do the outer walls of the the furnace where the probe face is mounted also get as warm as it would being against single wall pipe and 18 inches above a stove top?

As I mentioned before, I am very happy with my probes performance located 28 inches above the stove. My question is, how much do flue gasses really cool down in the 10 inches from where I originally had it located to where it is now 28 inches above the stove? Are the more reasonable readings the result of a cooler ambient location or the result of truly cooler flue temps? If it is because of the air temp at the location, perhaps the directions on the package for mounting should be adjusted.

In terms of the IR reading differently at different locations on the stove pipe, I have seen this as well. However, it has never been more than 20-30 degrees as I circumnavigate the pipe. Additionally, if the surface pipe values are so inconsistent, how can any single wall magnetic thermometer have value? Additionally, this raises my concern about the fluegard's package including the claim that it reads approximately 50% higher than single wall stove pipe values.

I agree, that a probe with no temp values and a simple "low," "normal," "high," may be the best ticket for ease of operation. Truth be told, showing the temps is of little value to the average person. In a similar example, how many cars on the road have an analog fuel gauge that reads in gallons? I have only ever Seen F, 1/2, E and that is good enough.

pen

 

[Battenkiller]

I had the occasion to talk with a couple of woodstove OEM’s about temp readings and asked them about flue-gas temps and whether the use of an IR meter is accurate when measuring the surface of the flue pipe; they said absolutely not... even single-wall pipe flue-gas must be measured inside. They testified the gas swirls and you can see different temps depending on where the measurement is being taken

My experience with my IR is that this is true at startup when the fire is sending up big waves of hot gases. My IR takes a reading every half second, and I can see the temps jump all over the place (but only +/- about 10ºF), even when the red dot is stationary. At first, I thought my IR was bonkers, but I finally came to the conclusion that this is due to the violent nature of the gases during a hot, open burn conducting the heat through the thin metal almost instantaneously. Readings taken later on once a stable burn was established seemed very steady. But then, won't there be internal temperature variations due to the same gas swirls?

Another danger might be that either an IR or a magnetic thermo might give a false negative regarding excessive flue pipe temps in a situation where a buildup of soot and creosote inside the flue pipe is insulating the pipe from the gases inside. A newbie burning inferior wood and building up massive amounts of creosote might get a false sense of security and run his flue temps up even hotter without knowing he is already in a hazardous situation. Just a thought.


Given the problems discovered in using the internal thermometers in varying situations, I think a thermocouple probe reading is the only sensible way to measure flue gas temps. Readings are basically instantaneous and are unaffected by any variance in the ambient environment. There are so many things you can do with the output of these devices as well. Someone here set up a stove temp monitoring device with his (was it Wes, I can't recall), and that would be really helpful to those among us who are basement burners.

If single wall surface pipe temps are so inconsistent, how can ANY brand magnetic stove pipe thermometer have any value?

I surely saw the irony in their statement as well. However, I feel that these devices are, at best, merely indicators of the current state of your burn. If you have a single-wall pipe, a magnetic thermo will be close enough in 99% of the cases. With double-wall pipe, you absolutely need an internal unit. In an ideal world, get the real temp with a thermocouple probe and a digital readout.

 

[WES999]

One test that would be interesting would be see what the difference between the Condar probe installed on single wall and double wall. I considered installing the Condar on my Regency upstairs stove ( it has DW pipe) but did not really want to drill a hole in the pipe.
I would guess with the bi-metal spring receiving less heat it may be more accurate.

 

[pen]

And the last reply. Now that he's getting less specific with answering my questions while still being very cordial, I say the conversation is politely coming to a close.

I'd say this last reply supports Wes's most recent claim: that the single wall's radiant heat is causing the probe to read high.

Here is our set-up for testing the probe meters. It is configured so
that there is some gap between the heat source and coil. This set-up
would more closely be like double-wall pipe or for testing catalytic
combustor probes that insert through the top or side of a woodstove.

So, no the exterior of the meter (coil) is mostly insulated from the
heat source; it's relying on the heat conductivity through the probe to
the coil for deflection.

We will continue to consult with different OEM's regarding flue temps
and see where that info leads us. I did learn this week that extra high
efficiency non-catalytic woodstoves have a much higher flue gas temp
than older models, mainly because the new firebox designs have the
highest temps at the very top of the chamber, thus closer to the exhaust
(flue).

Those higher temps are needed to burn all the fuel and to "cook" the
exhaust gases for clean burning.

We'll keep learning. Thanks for your help.

In the end, my opinion is that this probe will work fine for double wall as per instructions, but should be installed higher on the flue pipe for a single wall install.

I wish they would consider more "real world" testing and perhaps amend their instructions accordingly as I think this probe installed on a single wall pipe 18 inches up from the stove (being read as the gospel) would cause the average operator to run the stove too cool.

pen

 

[imacheezhead]

This may not be totally relevant to this thread but since you are talking about inaccurate temperature probes I'll give it a shot anyway.

I have a Consolidated Dutchwest that utilizes a condar catalytic temperature probe that I just replaced. I'm looking at this thing as it came out of the box and according to it my room temperature was 350 deg.! I installed it and it said my combustor temp. would get up to 1600 deg. This didn't seem right to me so when the fire started to die down I noted the temperature and it said about 800 deg. I took my digital meat thermometer and stuck the probe in the hole without touching the combustor and it said the temperature was about 400 deg. That raised my flag a little! I looked at some pics on the internet of the same probe I have and they also say 350 deg. I adjusted the probe according to what my meat thermometer said and now the temps seem to be more realistic and my maximum combustor temperature is around 1200 deg. I noticed that some of the probes have digits below the 400 deg. mark and they show a temp. of about 70. The one I have starts at 400.

Am I missing something here or are these probes leaving the factory uncalibrated?

Thanks, Jim

 

[WES999]

Just a thought, perhaps a washer say 2" or 3" dia. and a short spacer maybe 3/8" long installed on the end of the probe to simulate double wall pipe would improve accuracy.

This would shield the by-metal spring from some of the radiated heat from the single wall pipe.

If I would have thought of it earlier I would have tried it. :-S

 

[Troutchaser]

Maybe for SWall pipes the probe could be pulled out an inch from the pipe for a more accurate reading? Just a thought for all those who already have a hole drilled 18" up from the stove.
I wonder in their little test machine what the air temps are around the face of the probe?

 

[Todd]

Just a thought, perhaps a washer say 2" or 3" dia. and a short spacer maybe 3/8" long installed on the end of the probe to simulate double wall pipe would improve accuracy.

This would shield the by-metal spring from some of the radiated heat from the single wall pipe.

If I would have thought of it earlier I would have tried it. :-S

I tried that and it didn't seem to make much difference. There's too much radiant heat surrounding the whole area. I think Condar has to recalibrate those probes for single wall.

 

[Todd]

This may not be totally relevant to this thread but since you are talking about inaccurate temperature probes I'll give it a shot anyway.

I have a Consolidated Dutchwest that utilizes a condar catalytic temperature probe that I just replaced. I'm looking at this thing as it came out of the box and according to it my room temperature was 350 deg.! I installed it and it said my combustor temp. would get up to 1600 deg. This didn't seem right to me so when the fire started to die down I noted the temperature and it said about 800 deg. I took my digital meat thermometer and stuck the probe in the hole without touching the combustor and it said the temperature was about 400 deg. That raised my flag a little! I looked at some pics on the internet of the same probe I have and they also say 350 deg. I adjusted the probe according to what my meat thermometer said and now the temps seem to be more realistic and my maximum combustor temperature is around 1200 deg. I noticed that some of the probes have digits below the 400 deg. mark and they show a temp. of about 70. The one I have starts at 400.

Am I missing something here or are these probes leaving the factory uncalibrated?

Thanks, Jim

I'd send it back and get a new one. It shouldn't read 350 at room temp and you don't know if your adjustment is accurate.

 

[pen]

This may not be totally relevant to this thread but since you are talking about inaccurate temperature probes I'll give it a shot anyway.

I have a Consolidated Dutchwest that utilizes a condar catalytic temperature probe that I just replaced. I'm looking at this thing as it came out of the box and according to it my room temperature was 350 deg.! I installed it and it said my combustor temp. would get up to 1600 deg. This didn't seem right to me so when the fire started to die down I noted the temperature and it said about 800 deg. I took my digital meat thermometer and stuck the probe in the hole without touching the combustor and it said the temperature was about 400 deg. That raised my flag a little! I looked at some pics on the internet of the same probe I have and they also say 350 deg. I adjusted the probe according to what my meat thermometer said and now the temps seem to be more realistic and my maximum combustor temperature is around 1200 deg. I noticed that some of the probes have digits below the 400 deg. mark and they show a temp. of about 70. The one I have starts at 400.

Am I missing something here or are these probes leaving the factory uncalibrated?

Thanks, Jim

I'd send it back and get a new one. It shouldn't read 350 at room temp and you don't know if your adjustment is accurate.

go to the website, contact a person there and I am sure they will treat you well.

pen

 

[pen]

Just a thought, perhaps a washer say 2" or 3" dia. and a short spacer maybe 3/8" long installed on the end of the probe to simulate double wall pipe would improve accuracy.

This would shield the by-metal spring from some of the radiated heat from the single wall pipe.

If I would have thought of it earlier I would have tried it. :-S

I tried this and it made no difference.

 

[Peter B.]

I've simply gone back to using my 20 year old Condar probe, which I'm convinced provides more accurate temp readings than the three newer Condars I bought last year.

--

It may be a meaningless side note, but in the oven test I made (which mainly proved that oven tests give bogus results from probes), I noted that at three different temperatures, all of the probes gave consistent readings as factors of the actual stove temp... suggesting that they were responding uniformly.

However, the old probe factor was about 2.6x the actual temp, while the new probes read about 3.7x.

Interestingly, a fourth new Condar probe (a cat probe with 2" stem) read consistently LOWER than the old probe... for a factor of 2.4. (All the other probes have 4" stems.)

Needless to say, I haven't got much faith in any of the new probes. I should have returned them all, but I guess I just got lazy.

I'll sell them cheap, if anyone's interested.

Peter B.

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