I have two digital thermometers and decided to check the accuracy of them, the question was how? Common sense told me to get a pot of water to a boil and see what they read. Good roiling boil and one read 210.5 and the other read 210.7. I know different sea levels affect the temp. of the boil and I'm only about 300 ft. above sea level, am I doing this right? How do you check yours?
Thermometer accuracy
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I've read most people read/calibrate using ice water. Fill a glass with ice, then add water. Let sit for 5-10 minutes, and your thermometer should read 32 degrees F.
This is how I calibrate.
Just to add to this, crushed ice mixed with water is really the way you want to do the cold side calibration. I also used the elevation calc on the ThermoWorks website and at 300ft above sea level water boils at 211.48F.
Rev.
Crushed ice with just enough water to fill but not float the ice. You really need to check both. You could be accurate on one end and way off on the other end. It would be nice to calibrate in the middle for mash temperature but there is no easy way.
Human body temperature. The typical average is obviously 98.6F though some people have slightly different temps. I'm always reading slightly lower. Good reference point though.
Rev.
Saw a headline a while back saying that 98.6 is not correct for body temperature. I didn't read the article though.. I would really like to know that I have very good accuracy between 148 and 156.
My oral thermometer reads 97.4 My digital thermometer reads 98.2
My oral thermometer reads 97.4 My digital thermometer reads 98.2
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isomerization
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https://www.wired.com/story/98-degrees-is-a-normal-body-temperature-right-not-quite/
Don’t forget that your temp rises during the day too.
"Hausmann and his colleagues found an average normal temperature in adults of 97.7 degrees"
Interesting, cause as I noted above mine always reads lower. I typically read something like 97.4 or something around there. Seems to concur with their findings. It can still help to use body temp as a near mid-point check though. If one thermometer is reading say 96.7 and the others 97.6 I would say the 97.6 one's were more accurate.
I went online looking at lab thermometers as I used to have an Alla France one. I figured I'd order one but reading further I found that even those aren't perfectly calibrated.
Rev.
That was it!
I was not having good luck getting a boiling temp reading and while a crushed ice bath seems easier and more accurate it is not very close to the mash temps that I care about. I decided that a $10 lab thermometer was accurate enough to use as a reference so I use that to calibrate my dial thermometer.
Unless that lab thermometer was certified, its no more a reliable reference than what you had. But you are right to make sure your working thermometers are calibrated in the mashing temperature range. Boiling or freezing temps are too far away.
Soulshine2
Well-Known Member
I know Ive seen a chart that takes altitude into consideration and a calibration . I cant remember where . I agree that take a pot of water , boil it and it should read 212 ....give or take 2 degrees. or find a couple cheap kitchen/candy thermometers and take an average. 2 degrees either way isnt going to make or break your brew.
Though honestly exact temps (within reason) are not that critical to me but having repeatable temps are. My dial thermometer had clearly drifted and it was noticeably effecting mashing. I am pretty sure the lab thermometer will stay stable for years.
But if they're OK at boiling and freezing temperatures it's likely they will be OK at mash temps.
RPh_Guy
Bringing Sour Back
Where are you sticking your thermometers?
I calibrated my thermometer in both ice water and rolling boil. It reads a couple degrees low at boiling and a few degrees high in ice water, which results in.... it reads perfectly at mash temperatures. Perfect.
Soulshine2
Well-Known Member
ice water isnt ice ...it'll read slightly above it. like 34*
Au contraire, it is possible for solid ice and liquid water to coexist at the same equilibrium temperature, which is 32 F regardless of atmospheric pressure or elevation. I gave my ice and water plenty of time, like 30 minutes, to equilibrate, and I ensured only enough water to cover the ice was used and that the thermometer was thus also in contact with ice when taking readings. Science.
lolRegarding boiling and freezing temps, 212 and 32 are in reference to distilled h2o. Any additives i.e. non-distilled will have a temp variance from the expected normal .
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