Variability in a stovetop thermometer?

[SonOfEru]

I have a stovetop thermometer that we got when we bought a VC Defiant Encore 30 years ago. It says "Vermont Castings" on it, of course.

Just replaced the stove with another Encore from the same period [but only burned a few years so it's not very "old"] and wanted to see how it performed so I was taking temperature readings on the top and then on the slanted surface of the cat chamber on the back. I got kinda tired of moving it from one place to the other so I wanted a second thermometer, figuring I would start them both out on the griddle then move one to the back side. That way I could compare them and see how close they were so I could figure an offset temp if I had to.

I looked online for another of the same "Vermont Castings" kind, but was startled to see them at $39 each, while other brands were $10 to $15. I figured the VC thermometer must be very high quality. But I balked at the price.

Instead I picked up a Rutland thermometer today at Home Depot and it's really disconcerting. I took numerous readings, starting from a cold stove, and by the time the VC reached 700, the Rutland was only up to 500. And all the way up the readings were pretty consistent - the Rutland always very close to 70% of the VC.

Would the Rutland be a cheap instrument and just way way off? Or could the VC have gotten badly worn out over the years and be reading high by a consistent percentage?

Is there a lot of variability in stovetop thermometer brands? If so is there one that is recommendable?

If I want to flip the damper to run the cat, at ~450, I want to know I am somewhere close to right about it.

Thanks

 

[HomeinPA]

I wouldn't say a VC thermometer is any better or worse than one you'd buy a HD or Lowes. They just don't say Vermont Castings on them. Do you have an IR thermometer you can use on the surface to see which one is closer? Or buy a third one and put all three on and whichever 2 match or are closer, use them. If the first one you got is bad then you can return it.

 

[Mark8]

I wouldn't say a VC thermometer is any better or worse than one you'd buy a HD or Lowes. They just don't say Vermont Castings on them. Do you have an IR thermometer you can use on the surface to see which one is closer? Or buy a third one and put all three on and whichever 2 match or are closer, use them. If the first one you got is bad then you can return it.

If two of the thermometers are off but close you could be discarding the good one. I have eight tire air gauges and they all read different air pressures, ubelievable, now how do you know what one is correct.

 

[HomeinPA]

If two of the thermometers are off but close you could be discarding the good one. I have eight tire air gauges and they all read different air pressures, ubelievable, now how do you know what one is correct.

If 2 out of the 3 match or are close then I'd go with the odd of the third one being bad. In the case of the thermometers. Or you could have bought 2 crappy ones.

Your pressure gauges....depends how much they're off from each other I guess.

I guess in the end...Does anyone really know what time it is?? Does anyone really care?

 

[Mark8]

If 2 out of the 3 match or are close then I'd go with the odd of the third one being bad. In the case of the thermometers. Or you could have bought 2 crappy ones.

Your pressure gauges....depends how much they're off from each other I guess.

I guess in the end...Does anyone really know what time it is?? Does anyone really care?

Exactly, I ponder this kind of crap too much, was it the chicken or the egg that came first. Or do we really even know if it's 2018. I really think it's the Matrix.

 

[RobbieB]

My Rutland is more accurate than my Inferno but it does read about 10% low (400F actually 440F by infrared laser) and the Inferno read high.

 

[xman23]

All the ones I've had over the years have been very close to the same reading. I had an old one that the BI metal coil was cooked out of shape. I didn't notice it for some time. it put a small scuff mark on the stove top.

 

[bholler]

You guys do know unless you spend quite a bit on an ir thermometer they can be pretty inconsistent as well

 

[bholler]

But to the origonal question the old one is probably off. They do wear out. And as far as saying vc i am sure they just had someone like rutland print vc on them. And if they did make it i am sure it would look great but it probably wouldnt work very well and would need fixed every few years lol.

 

[SonOfEru]

Thanks all.

I thought of verifying with an IR but I dont want to buy one if I dont have to.

It looks like there is a lot of variability in bimetal thermometers. Probably even for those from the same manufacturer.

My hunch is that the old one has wandered away from reality. When it's cold it settles down to around 100 on the dial. But what was interesting was that the differences were not a consistent 100 degree offset. As they got hotter, the VC kept getting further ahead at a rather fixed rate. Every 100 degrees hotter on the Rutland, the VC got 140 degrees hotter.

I could get another Rutland but I didnt notice when I bought it that it doesnt have the thin wire loop for picking it up off the hot stove. I rigged my own with a thin wire from my toolbox, clunky but it kind of works. I would rather not end up with 2 Rutlands, but I dont really want to try a third brand. Bummer.

The potatoes are relatively small here, but I do hope to get reasonably accurate readings

 

[HomeinPA]

But to the origonal question the old one is probably off. They do wear out. And as far as saying vc i am sure they just had someone like rutland print vc on them. And if they did make it i am sure it would look great but it probably wouldnt work very well and would need fixed every few years lol.

Yeah, and when you went to fix it the damn bolt would break and you'd have to drill it and tap it and then special order the part to fix it and then throw in all the time and labor you spent and in the end you could have bought 3 brand new ones that would work better than the one you just fixed.

 

[begreen]

I have the original, glass covered SandHill thermometer that came with our VC Resolute I stove. Although I've read that it should get more inaccurate with age, so far it is doing great. I have verified this with an IR thermometer. This is after being on 5 different stoves since 19080 and occasionally pushed well past it's range. . I don't know what they did, but I really like this old thermometer. It is accurate, durable, easy to read and simply attractive. Too bad they stopped making them.


For modern thermometers the Condar stovetop seems more consistently accurate than Rutlands. For better accuracy get a TelTru.

 

[SonOfEru]

Well, I found a friend of mine has an IR thermometer. I presume it's closer to accurate than the bimetals.

Turns out the IR reads close to halfway between them.

So I am putting one on the top and the other on the shoulder in the rear, and I have taken a number of readings of each, paired with the IR reading. So I have a table of "conversions" that I can refer to.

So I think I'm set. Thanks for the inputs

SonOfEru