Magnetic Stack Thermometer Vs Probe Type

I installed one of the probe type thermometers on the stack of my coal stove this evening. It also has the magnetic one still on it. How much of a difference should there be between the two of them once the fire settles in for the burn?

During start up the probe one got up to 1150 at the peak while the magnetic one only got to 500. It was burning pretty good at that point. Now that the burn is established and it is settled in for the night, there is 375 on the probe and 200 on the stack with a 325 stove, .05 on the draw, and the manual flue damper is completely closed. Does this sound about right? I would guess that the gases inside the stack are hotter than the actual metal of the stack, but do these numbers sound about right?

sounds pretty good

hows the heat? nice and toasty?

Probe type would be a more accurate reading of exhaust temps, since its inside the pipe and directly in the exhaust path. Your magnetic will be much lower, since its on the outside of the pipe and gets room air around it and NOT directly against the pipe.

I have both on my stoves and there is a huge difference in temps if monitoring the same point.

I have both on my EFM. I usually see 300-325 on the probe and 150-160 degrees on the magnetic thermometer.

Now that was a good question and good answers. I have wondered about that, but never thought to ask while I was visiting this site. Thanks to all.

I use Ashcroft probe devices, more of an industrial use thermometer. Use a few of them I bought off of Ebay over the years. I thread a .25" male npt x .5" f npt pipe fitting adapter directly into the stack flue pipe. Thermometer screws into this adapter. Far more accurate than a magnetic.

I too have both a probe and magnetic thermometer on the exhaust flue of my furnace, and before my baro draft damper. As stated the probe is more accurate being directly in the path of the flue gases, and my probe registers about twice what my magnetic one does. So not a bad rule of thumb. Your temps sound right (to me) as my furnace has a nice sweet spot and seems to be happy when my probe temps are between 500-600degF. I have a whole house wood/coal furnace, and where we live in the U.P. of Michigan it cranks out a lot of warmth at those temps. Wife has even gone so far as to say a coal fire only when the daytime temps aren't going over freezing, since use of "windowstats"' are required if it warms up above freezing during the day! On "warmer" days we just use wood, and less of it during the day. Isn't coal great??

Cap wrote:I use Ashcroft probe devices, more of an industrial use thermometer. Use a few of them I bought off of Ebay over the years. I thread a .25" male npt x .5" f npt pipe fitting adapter directly into the stack flue pipe. Thermometer screws into this adapter. Far more accurate than a magnetic.

I'm sure it is far more accurate but for me its only a relative measurement. On my cookstove, I use the oven door gauge and on the cylinder a magnetic on the top of the barrel. In both cases the stack temps are much less than half of the stove surface temps so I know they are burning efficiently. Niether stove ever runs much hotter than 500 degrees so I'm not pushing anywhere near the limits, so a cheap magnetic provides all the information I need.