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Old 07-11-2007, 01:58 PM   #1
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Default Thermometer calibration

Anyone else really distrust their thermometer?

Here's an easy way to gauge (I know precision is what we seek, but lets get serious shall we? ) the reasonable accuracy of your thermometer.

I read this info off of a "How not to kill your baby" pamplet - you know what I mean.

Household hot water is (In toronto at least, I imagine it's pretty typical) ~60C.

I have an analog thermometer that tells me it's 50C. It will soon be run through my new corona mill out of spite Seriously though, I have a radio shack digi therm and it read right out at 59.7C

That one is a keeper.

Anyone have any input? Anyone want to flame me for poor scientific method ?

Just a little test if you have some concern about not hitting your temps right...

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Old 07-11-2007, 02:07 PM   #2
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My Local homebrew store sells calibration thermometers. Seems like I paid about $6. It's fragile but I only used it to test the accuracy of my digital unit then wrote down what the indicated readings actually are. I also used it to calibrate the thermometer in my Hot Liquid Tank to the most frequently used temp.

IMHO it was money well spend.

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Old 07-11-2007, 02:53 PM   #3
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Yes, look for something called a lab thermometer (same thing as a calibration thermometer). They are usually alcohol thermometers that are accurate to within a degree.

The other option is to use a glass of ice water and a pot of boiling water to calibrate your thermometer. Since you are a Foreigner we can use those easy metric numbers: thermometer should read 0 in the ice water (ice cubes made from distilled or RO water is best), and 100 in the boiling water (may need to adjust for elevation).

Just be sure to check that your thermometer is safe at this range of temp (e.g., most glass alcohol lab thermometers will burst at 100 degrees C).

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Old 07-11-2007, 03:04 PM   #4
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I have a dial and a digi that I use on my brews and every so often I will put them both in a glass of water...if they both read the same...I call that calibrated. I think the odds of them both being exactly the same amount of would be pretty low.

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Old 07-11-2007, 03:25 PM   #5
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Most of the mechanical dial type thermometers (like those that come with turkey fryers) have a nut on the back of the dial where the probe attaches. You can use a wrench on the nut to adjust the calibration. I did an ice bath (let it sit for a couple minutes) and adjusted it to 32 F and then tested it in boiling water boiling water.

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Old 07-11-2007, 03:55 PM   #6
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If you have a digital thermometer for checking your temperature, like the one that goes under your tongue, you could test it (assuming you are healthy) on yourself 98.6*. Then prepare a bowl of luke warm water, and use it to calibrate your brewing thermometer.

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Old 07-11-2007, 04:52 PM   #7
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No, you can't use your tap hot water as a gauge. I can adjust my hot water temp across a wide range. I currently have it set to 135F but can change it to 110 or 145 anytime I want.

I know you can also take other liquids with known boiling points to calibrate at a temp closer to your desired range such as mash temps. For example, Bromine boils at about 59C or 138F at sea level. Not sure if it's safe or not. Pure Isopropyl alcohol boils at 82C.

You could also calibrate your thermo to 72C by boiling water on top of Mt Everest.

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Old 07-11-2007, 05:00 PM   #8
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Wow, lots of interest.

I wasn't claiming that this is an excellent way to do it, just a little fun test

It is of course based on the same theory as most of the other posts, which is a known temp against which to compare.

so, IF (note big IF) I know the temp of my hottest possible tap water, why worry about it?

I understand the desire for precision, but I'm happy + or - 2 to 3 C

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I try not to drink anything harder than Gin before breakfast - W.C. Fields

Primaries: Ed's Haus + Munich, Ed's Haus + medium crystal

Secondaries: suck :)

Bottles: Chili Stout, Dry Irish Stout, Bitter Ass IPA, Headstrong Munich Lager clone, Lawnmower ale with chocolate and munich malt

Bulk Aging: Wildberry Sweet Mead - Orange Vanilla Dry Mead

Up Next: Orfy's Old Speckled Hen and an IPA of some kind

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Old 07-11-2007, 05:03 PM   #9
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http://www.professionalequipment.com...-thermometers/

Problem solved.
Comes with a NIST cert. Samples 1/sec and displays in .1° F increments.
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Old 07-11-2007, 05:07 PM   #10
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Quote:
Originally Posted by olllllo
Samples 1/sec and displays in .1° F increments.
Very cool! But hey, my all-grain equip is coming along nicely. Sometimes you just need to be a cheap ass, you know :P
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I try not to drink anything harder than Gin before breakfast - W.C. Fields

Primaries: Ed's Haus + Munich, Ed's Haus + medium crystal

Secondaries: suck :)

Bottles: Chili Stout, Dry Irish Stout, Bitter Ass IPA, Headstrong Munich Lager clone, Lawnmower ale with chocolate and munich malt

Bulk Aging: Wildberry Sweet Mead - Orange Vanilla Dry Mead

Up Next: Orfy's Old Speckled Hen and an IPA of some kind

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