Different readings from IR Gun vs Rutland magnetic thermometer - which to believe ?

[Seastrike]

I placed the Rutland back in the opening at the top of the Jotul C550 insert where the heated air exits;
When measuring temp with the IR gun, I measure at same location.
The temps between the 2 units vary by nearly 150F.

Last night, with the C550 full of 2 yr split & seasoned Elm the Rutland was reading 575F and the IR gun 415F.
Before using the Rutland, I was always wondering why I couldn't get the stove over 425F...maybe I was there the whole time...but how to tell which is giving me the true reading (without purchasing another gun or thermo.

Thoughts ?

 

[Monkey Wrench]

Put the Rutland in the kitchen oven set at 300, than 400 etc and check it.

 

[Battenkiller]

Fill a pan with ice cubes, cover with water and let sit for about 10 minutes. IR gun should read a surface temp of about 32ºF.

Heat a pan of water up to a full rolling boil. Water boils at 212ºF at sea level (atmospheric pressure = about 30" mercury), but because of some evaporative cooling at the very surface, the IR gun should read about 200ºF (depending on atmospheric pressure).


If these two things aren't even close to the stated temperatures, your gun is off. If they are spot on, you might safely assume that the gun will be reasonably accurate at stove top temps.

 

[sunglider]

For what it's worth, I have Condar and AW Perkins stovetop thermometers. They agree with each other perfectly but both run about 150 degrees higher than my IR. I will check the IR as suggested above this weekend.

 

[Seastrike]

Thanks all. Your suggestions make perfect sense. Will try them tonight.

 

[Lighting Up]

Put the Rutland in the kitchen oven set at 300, than 400 etc and check it.

Just did this tonight and found my rutland magnetic thermometer is off by 100 degrees higher. Has anyone tried a oven thermometer in their wood insert stove or do the sell a better magnetic thermometer now then 2 years ago?
md

 

[wendell]

Not sure who makes it but the most accurate magnetic thermometer I have seen is the one Woodstock sells. It is always within a few degrees of my IR.

 

[bboulier]

Mine are usually pretty close - within 10 degrees of each other.

 

[Lighting Up]

Not sure who makes it but the most accurate magnetic thermometer I have seen is the one Woodstock sells. It is always within a few degrees of my IR.

Thanks Wendell,
what's the name of the store and location...when you goggle woodstock it's all concerts.
thanks again
md

 

[Danno77]

I have two thermometers. One for the stove top and one for the stove pipe. One was reading higher than the other one when placed on the same spot, When I got my IR thermometer it matched one perfectly. I immediately took the wrong one off and forced it to read correctly for the temps I was running at the time (like 500 or something).

It's now off at low temps (like <250-300) but is right on with the higher temps, which is all I really care about.

One is a rutland and one is another brand. Can't remember which one was off. I'll post later. Unless, of course, I forget. lol.

 

[joefrompa]

It'd be interesting to find out how many stove owners are running their stoves well under the operating temperature they expect.

For example, I'm using a Rutland stove-top and recently it's been shooting up to 700 quite easily when I stuff the box full of semi-seasoned wood on top of a hot coal bed and a 425 start point. My fan is blowing on high and my air is choked to about 30%, but the power of it is drafting like crazy and I'm getting secondaries out the wazoo. I love it!

But am I really only at 575-600? Is this actually how I should be running my stove, rather than trying to get it to cool back down to 600?

From a fire standpoint it's roaring/gates of hades, secondaries are looking phenomenal, wood is being consumed very slowly, and I'm actually air washing my glass....but because my Rutland says 700 (or above), I try to make sure it quickly cools down by 75-100 degrees.

 

[Danno77]

It'd be interesting to find out how many stove owners are running their stoves well under the operating temperature they expect.

yeah, I guess I didn't say it, but that's what was happening to me. i was freaking out because I thought I was overfiring, but I was really running about 150 degrees cooler than the thing was reading.