Trouble calibrating my thermometer

[Starkman]

Okay, so I've got one of those inexpensive skinny meat thermometers with the dial on the end, which can be adjusted by moving the nut underneath the dial. Here's the problem.

I calibrated it by inserting it into ice water (seemed to be what a lot of Web sites suggested) until it read 32 degrees. So far so good.

Now, I'm at 4000 feet above sea level, so I'm assuming I'll need to keep in mind about a one-degree drop per five-hundred feet, about eight degrees less than sea level.

Well, I then boiled some water and tried the thermometer, and it came out at about 190 degrees, which is twenty-two degrees less! What's going on here? Any ideas what I should do with this fool thermometer?

Thanks,

Starkman

[Kerry Beal]

If it's a meat thermometer the calibration is probably important in the 100 plus range and is not particularly accurate at lower temperatures. It's a one point calibration - so I'd calibrate for boiling water and ignore the reading it gives you at room temperature.

[Starkman]

AAAAAAAH! (Thanks much, Kerry. I'm just frustrated trying to figure this out.)

Well, my step-dad, who's a native of this area, said that he heard that water boils around here (4000 feet above sea level) at about 191 degrees F. I thought, But that's a 21-point drop from 212 degrees F.!? How's that possible (unless my cooking notes about adjusting for elevation are incorrect (subtract 1 degree per 500 ft).

Well, it's just at about 191 degrees that my meat thermometer is hitting when I boil water. So, I'm really confused now!

I discovered this whole issue when I was roasting a chicken this evening. It read 170 degrees F., but it was still not done. That's what got my attention. So I'm really not sure what to do at the moment about this fool thing. (If...if I can just get the kitchen window open, and throw the thing...)

Starkman

Edited October 22, 2010 by Starkman (log)

[Kerry Beal]

Looks like at 4000 ft the boiling point of water is 206.8 Table here . There is also correction for barometric pressure.

[Porthos]

Now, I'm at 4000 feet above sea level, so I'm assuming I'll need to keep in mind about a one-degree drop per five-hundred feet, about eight degrees less than sea level.

That altitude adjustment is approximate but useful. The barometric pressure also affects the boiling point. but something close to 204 degrees F is what you should be seeing.

You can google water boiling point altitude to get more detailed info if you wish.

[Starkman]

Now, I'm at 4000 feet above sea level, so I'm assuming I'll need to keep in mind about a one-degree drop per five-hundred feet, about eight degrees less than sea level.

. . . but something close to 204 degrees F is what you should be seeing.

Yup, that's what I thought, and that's what I had it set...until I checked the chicken and it registered 170 degrees in the thigh area, but was still bleeding and a tad raw.

So my notes are correct, and...the thermometer really does need to go out the window!

Thanks all,

Starkman

[Kerry Beal]

Now, I'm at 4000 feet above sea level, so I'm assuming I'll need to keep in mind about a one-degree drop per five-hundred feet, about eight degrees less than sea level.

. . . but something close to 204 degrees F is what you should be seeing.

Yup, that's what I thought, and that's what I had it set...until I checked the chicken and it registered 170 degrees in the thigh area, but was still bleeding and a tad raw.

So my notes are correct, and...the thermometer really does need to go out the window!

Thanks all,

Starkman

Yup - sounds like a bum thermometer. Time for a TruTemp.

[budrichard]

These simple dial thermometers are probably not more than +- 20F degrees in accuracy anyway.

Put in boiling water and adjust to 204. It should be okay for the upper range of meat and chicken. What is more important is repeatability of the reading.

If you demand precision than decide on what precision you want and then read the manufacturers specifications on accuracy and repeatability. The more precision you want the more you pay.-Dick