mag. thermometer

I'm not sure a magnetic stovepipe thermometer will respond the same when baked in the oven as it does when stuck on a stovepipe. On the stovepipe, it has at least some convection cooling, whereas in the oven it's totally immersed in the hot environment. I have two mag thermos (different brands), and when I put them side-by-side on a stovepipe, there's about a 50F difference between them. I haven't baked either of them in the oven. In any case, I think it's fair to say that these are not precision instruments. Rick

...In any case, I think it’s fair to say that these are not precision instruments. Rick

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- agreed. Mag thermometers give you a general idea of your stove's temp. Just be sure to place them on your stove or stack per your manufacturer's requirements and you should be good to go. If you want to be absolutely sure, you could get an IR thermometer or internal probe but it's not absolutely necessary. Careful observation of your stove and environment over a long period of time help make up for the mag's shortcomings

I have discovered with my mag. therm. that I have to pick it up now and then and rewind that metallic band on the bottom. Meaning I wind it up tight and let it spring and go boing,boing!! Then the miserable piece of metal will begin to give a sensible reading again.


Don`t know why this works? but it seems to do the trick. ;-)

They're also prone to the little pointer getting stuck on the face. Sometimes a little gentle pry with a knife blade will free it back up. Rick

I use mine on the top of the insert. Bought a new one last week as I had baked the paint right off my first one (anyone want a polished aluminum trend indicator?) - found that the new one read 300*F higher than the old one, which meant I was at over fire 10 mins after kindling light off. I was able to adjust it my twisting the magnet on the back - essentially rotating the entire spring mechanism separate of the face.

I also discovered that a good grill surface thermometer is half the price of a magnet mount unit marketed for a stove - so I'm off to the local restaurant supply house soon to get one. It might even be accurate.
Here is one I found for less than 10 bucks - http://www.amazon.com/gp/product/images/B0009XBILS/ref=dp_image_0?ie=UTF8&n=286168&s=garden

Confucius says, "A man with two watches never knows what time it is" I suppose the saying would extend to thermometers as well. But from what I've seen it's not uncommon for the magnet thermos to be off by 100º or more. It's not uncommon for home ovens to be off by nearly as much! So, you're definitely in the ballpark!

I just got my IR thermometer today and it confirmed what I've suspected all along - my magnetic thermometer is off by a substantial amount. When the mag reads 150, so does the IR. When the mag reads 775, the IR reads 590.

I've got an alcove installation so the only place I've been able to put a mag. therm. is on the stovetop and I've been constantly worried about how hot it reads. Now that I've got the IR and can get an actual read on the liner pipe, I'm a whole lot less concerned. When the IR was reading a stovetop temp of 590, the liner temp was 225. The back of the stove as far back as I could aim the laser was only reading 425. This in a stove whose manual says that a medium burn is 600 and a high burn is 800. No wonder I haven't been able to get this thing to throw as much heat as I expected.

Are you shooting at a stainless steel liner? If so, that will throw the IR gun off by a considerable amount. The emissivity of stainless steel is ~ .59 ish while most guns are calibrated for a flat black surface of around .95

To figure the difference, you would be looking at 775F/.95 = X/.59 so X ~ 480F, so if the pipe was truly 775F, you'd read around 480F on your IR gun. If it is black pipe, or you put a squirt of flat black stove paint on it and aim the gun at that, then you're probably reading close to the proper temp.

Was the oven still on when you pulled the mag thermometer out? If it was Electric oven that Element down below gets hotter the 350F, it turns off and then back on to maintain that temp. I would shut the oven off and let it sit for about 1 min before pulling the thermometer out, I bet it might be a little closer.

I also agree with Cozy Heat, I have had an IR gun since 2001, (got it for automotive use) and Anything shinny and it gives you a very bunk reading. Also if you hold it down and move it left to right I bet you will see a difference of temp as well. They are good for a quick idea of the temp, but don't think its any more accurate then the mag thermometer.

cozy heat said:

Are you shooting at a stainless steel liner? If so, that will throw the IR gun off by a considerable amount. The emissivity of stainless steel is ~ .59 ish while most guns are calibrated for a flat black surface of around .95

To figure the difference, you would be looking at 775F/.95 = X/.59 X ~ 480F, so if the pipe was truly 775F, you'd read around 480F on your IR gun. If it is black pipe, or you put a squirt of flat black stove paint on it and aim the gun at that, then you're probably reading close to the proper temp.

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Oh! Thanks for letting me know!

Yum . . . nothing better than fresh baked magnetic thermometers fresh out of the oven . . . slather a bit of butter or blueberry jam on them and wow . . . you would think you have died and gone to heaven.

I discovered, on a -10 degree night (which seems to have the effect of doubling my draft, and giving me no control over the stove) that my Rutland thermometer will read 700 while my IR thermometer reads 750...775...800...luckily it leveled off at 800!

The needle wasn't stuck, I can push it with my finger. It just doesn't go above 700 in reaction to heat. Nice, huh? The thermometer is pretty accurate the rest of the time (although it does lag behind a lot if I heat the stove up quickly) Makes me wonder about a certain Hearthstone stove that was accused of being overfired. Could've been my thermometer's little brother on that stove.

put it in boiling water that way the 212 degrees known to be true will always be accurate as a test

The thing that disturbs me most about this thread is the fact that you have to eat T.V. dinners

Does anyone have a link to any other type of stove top thermometer that would be more accurate that the magnetic spring type? I suppose an IR is more accuate but you cant just leave it on top of the stove and all those gas grill types don't go up high enough. There's got to be something better out there.

lexybird said:

put it in boiling water that way the 212 degrees known to be true will always be accurate as a test

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Well, now, at Standard Temperature and Pressure, that's the accepted value, but it depends on your particular conditions. Right now at my house the boiling point of water would actually be 206.398F. Rick

http://www.csgnetwork.com/h2oboilcalc.html

The converse side is...why does it really matter. If the room is cold, I'm going to burn my stove hotter and if the room is hot, I'm going to burn the stove colder. As long as the top isn't glowing and I've got some type of secondary burn going on (or warming up to it, or cooling off from it) I don't really care what the stove top temp is. Within ~100º, I could probably hold my hand up and tell what the temp is - That's as close as I care about. I've got an IR 'stat and a little flat black patch painted on the liner and stove top for some semi-accurate readings. But I probably zap the 'stat at the stove ~10 times a season just for the heck of it more than anything.

Whatever. I have mag thermos stuck on my single-wall stovepipes and I like having them there. If I had a hand-held IR thermometer, I'd probably just forget where I put it. %-P Rick

Wess999 has the ticket right here. Thermometers with an alarm you can set to overfire temps or reload.
https://www.hearth.com/econtent/index.php/forums/viewthread/32390/