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Old 03-23-2013, 04:49 PM   #1
PackerfaninSanDiego
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Default Thermometer Discrepencies

I have 3 thermometers and they all read different temps. I have the two "stick" types that clip on to the rim of the boil pot and the type that screws in to my pot. Any advise on purchase of a thermometer that is 100% accurate?


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Old 03-23-2013, 04:54 PM   #2
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I bought a digital one that was on Amazon that has a calibration screw. What ever one you end up buying, make sure you can adjust it.


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Old 03-23-2013, 04:54 PM   #3
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I've been using a floating thermometer lashed to one of the BK/MT handles with good results. I just bought a clip on as well,but haven't gotten to use it yet. I understand that the dial types need to be conditioned first to get them to read acurately. First into boiling water & see what it reads. Then into ice water. I noticed cooking thermometers need this too to get the needle to sweep correctly. I 1st learned of this from my daughter,who is a chef.
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Old 03-23-2013, 05:11 PM   #4
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All measurement tools are accurate until you have more than one.

My advice (that I seem to have to repeat a lot to friends) is to pick the one closest to accurate (check via ice bath and boiling water) and hide the other two. Having more than one thermometer will serve to do nothing but mind-eff yourself.

The least expensive way to get yourself a new thermometer that you could trust (IMHO) is to hop on eBay and pickup up a PT100 RTD from the China-land (if this makes you feel dirty, go to your local micro and support local business afterwards) then pick up something that can read the PT100 and display a calibrated value (like a PID) and slam it all in a project box or small electrical enclosure. This little bit of work would result in an accurate thermometer for a fraction of the cost of a lab thermo.

In my experience, stay away from the two wire (thermocouple) sensors like you find on walmart style kitchen thermometers or the kind that will plug into some multimeters. These will tend to shift their reading with time, but it occurs slowly enough that you generally don't catch it until you are mashing 5*F off.

Yatta yatta yatta, you can also just hunt down industrial/lab thermometers on eBay, but they tend to go for a premium unless you grab something that has been through hell and back.
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Old 03-23-2013, 05:50 PM   #5
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^solid advice. I too have three thermometers that are all about 6 degrees off at mashing temps. One of them is a pretty pricy calibrated digital unit, one is a dial thermometer, and the third is a cheapo glass lab thermometer. You have to measure them all in boiling water and ice water to see which one is most accurate. Now I use that one for critical temp measurements and use the others for guideline type temps. Ironically, the most accurate thermometer I own is the standard $3 red alcoho glassl lab thermometer. Sometimes the simplest option is the best.
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Old 03-23-2013, 06:00 PM   #6
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Quote:
Originally Posted by tjpfeister View Post
All measurement tools are accurate until you have more than one.
Bingo!
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Old 03-23-2013, 06:01 PM   #7
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buy a thermopen and be done with it forever.
Its pricy but I LOVE it.
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Old 03-23-2013, 06:22 PM   #8
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if you know what temperature they show in boiling water, then just offset your mash temps. it's not that big a deal, and you don't have to buy new equipment all the time. we used to set offsets in my lab at least once a month depending on the thermometer and the impact to quality. I'd find the offset every time you brew if you are finding it a problem.
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Old 03-23-2013, 06:24 PM   #9
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bottom line, even a thermocouple has to be calibrated regularly, and they will do it exactly the same way: boiling stuff.
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Old 03-23-2013, 06:49 PM   #10
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My mechanical would not calibrate at both freezing and boiling but my digital would. I calibrated the mechanical at 155f according to the digital.


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