Flue Thermometer

Double or single wall?

My probe type Condar just pulls out for cleaning. No problem at all. They're only calibrated for double wall, though. I think it's accurate enough for this application, and I like having it a lot. It helps to keep the burning efficiency up.

If you only have single wall, then I believe that your options are limited to a surface type unless you get a more expensive type. Come to think of it there is a probe type thermometer that has the bimetal inside the probe which would make it more accurate. I'll look it up.

Tel-Tru was what I had in mind. I can't find the model just now though.

If you have to go surface, maybe you can temporarily use a thermocouple to calibrate it.

Most use this Condar: http://www.condar.com/stovepipe_meters.html

I don't have it myself because I have double wall, but it looks like the numbers just report the surface temp like any other surface thermometer would and the colors indicate safe areas. The rule of thumb seems to be that the internals are about double the surface temps. But there will be a lot of variables to that as you can imagine. I think the directions say to put it at 18".

I tried using something like those ring terminal probes on my stovetop with my PID controller, but I found that it was always too cool because the up side was exposed to ambient. Do you have that problem using those?

I ended up with a basic bead type that reports much more accurately. The lead doesn't seem to mind the heat, I think it's fiberglass sheathing.

I was wondering what you thought of that.

The condor ChimGard Stovepipe Thermometer is the best one I have used on my SW pipe, and I just ordered a Condor Inferno Stove Top Meter
All of these Thermometers read temperatures ,The only calibration is the zones and such painted on the face, the inside pipe temp will be the same whether it is SW or DW
I can run my stove fine with the magnet mounts but was thinking of putting in a probe myself


From what I gather from the instructions( the first sentence in red) the probe can be installed on SW or DW pipe ( second sentence in red ) ,the magnet and the eyelet hold it in place , I think ?
But , I could wrong about this

http://www.condar.com/probe_meters_dir4use_woodstoves.html
Directions for Use
Condar's FlueGard (3-39) Thermometer is designed for insertion into the stovepipe, with the end of the probe approximately centered inside the flue for accurate readings.
To install a FlueGard Thermometer, drill a ¼-inch hole in the flue pipe at least 18 inches above the top of the stove or furnace. For double-wall pipe, drill a ¼-inch hole in the outer wall, and a 3/16-inch hole through the inner wall. Position so the thermometer can be read easily at a glance. Slide the magnet then the eyelet onto the stem of the thermometer; and insert into the hole.
When properly installed, the FlueGard accurately reads flue-gas temperatures, with an error margin less than 5%. If placed closer than 18-inches from the top of your stove or furnace, the thermometer will read slightly higher. Creosote on the stem of the thermometer will have little effect on the readings. When used on horizontal stovepipes, add 6% to temperature readings due to lower heat transfer. Before cleaning your flue pipe, remember to remove the thermometer.
Guidelines for Probe Thermometer Temperature Readings Consult your stove manufacturer's manual for precise temperature recommendations. See below for approximate guidelines, if the FlueGard is installed properly on the flu pipe. Note that flue gas readings are approximately 50% higher than surface temperature readings:
100°F to 400°F: Temperature too low. Incomplete combustion, causing smoke, soot and hazardous creosote. Open draft and/or add dry fuel.
400°F to 900°F: Safe operating temperature. Complete combustion and best efficiency.
900°F to 1200°F: Wasting energy, possibly overheating. While high temperatures are often reached on initial firing, should not be maintained for normal operation. Reduce draft.

HDRock said:

From what I gather from the instructions( the first sentence in red) the probe can be installed on SW or DW pipe ( second sentence in red ) ,the magnet and the eyelet hold it in place , I think ? But , I could wrong about this

Click to expand...

I wondered about that too and I emailed the company that question. They told me that the probe-type FlueGard is not good for single wall. They just couldn't make it accurate enough.

Ok , I read a bunch of info on the FlueGard and , I was wrong, and I will stick to the surface mount Thermometer for my SW pipe and stove top , as a good general guide running my stove .

I anyone wants to read some of the extensive info , It starts here
https://www.hearth.com/talk/threads/is-this-flue-temp-probe-full-of-it.46304/

And continues here, https://www.hearth.com/talk/threads/condar-temp-probe-vs-the-thermocouple.46978/

Sprinter said:

They told me that the probe-type FlueGard is not good for single wall. They just couldn't make it accurate enough.

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+1 Same thing they told me, Their magnetic ones have worked the best for me on single wall comparing with the IR gun.

Todd 2 said:

+1 Same thing they told me, Their magnetic ones have worked the best for me on single wall comparing with the IR gun.

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So you have been able to compare. Does the Fluegard agree with the IR well? Or how much variation is there?

For just a few dollars more than a magnetic mount thermometer, you could get one of these:
http://www.ebay.com/itm/Digital-Tem...167?pt=LH_DefaultDomain_2&hash=item3a724cecdf
and a probe type thermocouple inserted into the pipe( I wouldn't use a ring mt), you could have a nice setup.

I've been eyeing this.
http://www.auberins.com/index.php?main_page=product_info&cPath=17&products_id=292

I also installed the Condar Fluegard in my double wall pipe in addition to my stove top temp gage. Being new to burning wood it has helped me understand how to monitor my new stove at safe temps.

Sprinter said:

So you have been able to compare. Does the Fluegard agree with the IR well? Or how much variation is there?

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The Fluegard (probe) reads with in 10 deg. +/- in the 300 to 600 range with my oil furnace flue probe tester. But when the furnace flue tester reads 800 deg the FG reads 950 deg. so at the top of its range it does read higher than it is but in the middle of its range, what I consider the operating range it reads very accurate. Never tested the lower side of 300.
I remember the back of the package said to replace yearly or so many hrs if I recall correctly. ?

I have 3 of the condar magnetic ones, 2 of them are on the money with the IR from 200 - 700 deg. the other one reads about 50 deg. to hot side give or take a few but it has been torchered a few times back in the day….

I have been told to get a thermometer that its intent range of use favors the middle of its range for best accuracy, seems to be true for the condar probe. I like it, keeps her from melting my new stove and it is accurate in the cruse range.

Todd 2 said:

The Fluegard (probe) reads with in 10 deg. +/- in the 300 to 600 range with my oil furnace flue probe tester. But when the furnace flue tester reads 800 deg the FG reads 950 deg. so at the top of its range it does read higher than it is but in the middle of its range, what I consider the operating range it reads very accurate. Never tested the lower side of 300.
I remember the back of the package said to replace yearly or so many hrs if I recall correctly. ?

I have 3 of the condar magnetic ones, 2 of them are on the money with the IR from 200 - 700 deg. the other one reads about 50 deg. to hot side give or take a few but it has been torchered a few times back in the day….

I have been told to get a thermometer that its intent range of use favors the middle of its range for best accuracy, seems to be true for the condar probe. I like it, keeps her from melting my new stove and it is accurate in the cruse range.

Click to expand...

Thanks. It's good to know that they all match pretty well. Were you able to test the magnetic surface Condar with your internal furnace flue tester to see the relationship between the surface temp and internal? I'm told that it's about 2 to 1 but never heard any actual measurements. BTW, what is that furnace flue tester?

Sprinter said:

what is that furnace flue tester?

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Its an older Bacharach stem dial thermometer that I used when I serviced and installed oil furnaces, it came in a kit and it has a range from 200 - 1200 deg. The service guys told me the newer ones are crap and if i ever wanted to sell it…..

Sprinter said:

Were you able to test the magnetic surface Condar with your internal furnace flue tester to see the relationship between the surface temp and internal?

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Sure haven't they IR'd super close on the out side and used the 2 to1 theory myself. I bet its close from what Ive read on here.