Beavdowg
Well-Known Member
What's a good way to calibrate your thermometer?
Thermometer calibration?
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Scooby_Brew
Well-Known Member
I do it this way: ice water full of ice in the fridge for 10 min, it should read 32F or 0'C.
jkarp
Well-Known Member
Boil temp is too variable. Comparing to others is useless unless one is a NIST traceable lab thermometer. Fortunately, they're pretty cheap.
boredatwork
Well-Known Member
So basically the answer is buy a calibrated thermometer.
While you could check the 32F temp with ice water, that is not an exact method. And you cannot check boiling temp because although water boils at 212F, boiling water can certainly be hotter than that.
So you are left with one unreliable calibration point (32F) - but as far as I know thermometers are not uncalibrated linearly. In other words, just because it is accurate at 32F doesn't meant it will be accurate at 212F or 150F, etc. This is why calibrated thermometers are tested at several points.
So I really think the only way to calibrate a thermometer is to buy a thermometer that you can trust is already calibrated.
While you could check the 32F temp with ice water, that is not an exact method. And you cannot check boiling temp because although water boils at 212F, boiling water can certainly be hotter than that.
So you are left with one unreliable calibration point (32F) - but as far as I know thermometers are not uncalibrated linearly. In other words, just because it is accurate at 32F doesn't meant it will be accurate at 212F or 150F, etc. This is why calibrated thermometers are tested at several points.
So I really think the only way to calibrate a thermometer is to buy a thermometer that you can trust is already calibrated.
If you heat a 40% alcohol solution (aka vodka) in a water-bath, the temperature will plateau at 172F until the alcohol is mostly gone. Most useful for mashing.
This will be off if your elevation is extreme, but for 95% of the USA; it's good.
This will be off if your elevation is extreme, but for 95% of the USA; it's good.
SpanishCastleAle
Well-Known Member
That's a great tip David.
I have a calibrated thermometer (similar to a thermopen) but I hate to use it because it's my Sunday best and I want to have it around for when I really need it. It's also only in Celcius and I still don't have a good 'feel' for Celcius...I still 'think' in Farenheit.
Crushed ice in an insulated cup with just enough water to cover = 0.3 C
Boiling water in a teapot (lid off, spout open) = 100.1 C
That's @ almost exactly 36' above sea level.
I always use the teapot because I boil water in it every morning anyway.
I have a calibrated thermometer (similar to a thermopen) but I hate to use it because it's my Sunday best and I want to have it around for when I really need it. It's also only in Celcius and I still don't have a good 'feel' for Celcius...I still 'think' in Farenheit.
Crushed ice in an insulated cup with just enough water to cover = 0.3 C
Boiling water in a teapot (lid off, spout open) = 100.1 C
That's @ almost exactly 36' above sea level.
I always use the teapot because I boil water in it every morning anyway.
JVD_X
Well-Known Member
To add to this... depending on how much you want to spend (and although this may not be practical) you can send any thermometer out to get calibrated. You can even specify the points at which you want calibration. However, all thermometers drift so over time you would need to get them calibrated again.
Generally speaking though... I depend on my RTD to give the most accurate temperature.
I can think of a way that you could calibrate at 98.6 F as well...
I think it rhymes with "shove it up your ass".
Buy a lab thermometer for about 7 bucks.....Then put it and your digital one in a coffee travel mug with water arouing 170 degrees....Then as the temp drops, compare and keep notes on the difference betwqeen the two.....Usually if your digital is off by 1 degree, it will always be....
You want to calibrate it at those temps, 150-170, because thoses are the important temps to hit when doing your mash, sparge, ect......
You want to calibrate it at those temps, 150-170, because thoses are the important temps to hit when doing your mash, sparge, ect......
SpanishCastleAle
Well-Known Member
My understanding is that most people do not have that exact internal temperature...I know I don't.
MajorTom
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That's right... I have run about 97.5 for years... So if I find myself at 98.6 it means I'm sick! I always knew I wasn't normal.
bakins
Well-Known Member
My RTD/PID setup was off by 8 degrees. I used my lab thermometer to calibrate and still check at least once during each mash. It seems accurate at all temps, everything was just shifted by 8 degrees. Had the same with my other thermocouplers.
bakins
Well-Known Member
Not sure if the story is true, but supposedly 100 degrees F was Mrs. Fahrenheit's rectal temperature.
JVD_X
Well-Known Member
I imagine this being extremely rare - I would have returned the RTD. Maybe it was the same ones they used to test the new Boeing 787
BTW - have your checked the positioning of your RTD in the mash? Sounds like a positioning issue.
