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Taking your mash's temperature

cmbrougham

Grandmaster Brewer
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Sep 30, 2003
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Location
Northern Michigan
After two flubbed AG batches due to a messed-up thermometer (it was reading about 30-40F higher than it should), I need to figure out a good way to measure the temperature of the mash/grain bed. The thermometer that went bad is one of those wire probe digital types. Apparently, moisture has gotten into the probe and is throwing off the reading. My mash tun is a 48 quart cooler setup. What do you use or recommend I use to check mash temps?
 
Colin,
  I use the cheap $6 floating thermometer from the brew store.  I have about three of them so I can have one in the mash, one in the hot water pot, one in the boiler, etc...

 You can always cross check them by putting a few in a glass of water and verifying that they are about the same temperature.

 Simple, and cheap....

Brad
 
You can also check how accurate your thermometers are by putting them in a glass of crushed-ice water -- they should read 32F/0C. Then put them in boiling water -- they should read 212F/100C (in Michigan, at least). From there you can adjust as necessary.

If you're adventurous, get a weldless thermometer thingee -- zymie's stuff is good. That might be a good way for you to go.
 
CJ,
Once again I concur with you -- ice/boiling water give you a clear reference point aside from the "relative" measure of the individual thermometers.

Just out of curiosity - what's a weldless thermometer thingee??

Brad
 
I did calibrate three dial thermometers in boiling water last night, when I discovered how far off my digital thermo was. There's those little hex nuts that let you set where boiling (212F) is. I'll also check them in the ice water... thanks for the tip!
 
I started with a 48 qt cooler.  My inexpensive solution was to purchase a long stem dial thermometer. The stem is 11 3/8 long. I calibrate it @ 155 degrees ( to cover mash range best) with the glass thermometer.
The I drilled a small hole through the top of the cooler to insert the stem through the top into the mash.

This works great. The thermometer accurately tracks mash temp when the lid is closed. When the lid id raised, the thermometer stem is out of the way for stirring etc.

Preston
 
I have:
*A $50 18-inch Mercury thermometer/Hygrometer  from Fisher Chem.
*A cute little  cheap-O  alcohol thermometer/hygrometer from  Midwest (its got a potential Alcohol scale I like)
*A really cheap-O Taylor Digital pocket type (I clip it to my Fermenter jacket)
*A $20.00 Polder thermometer with the long probe (http://www.amazon.com/gp/product/B000P6FLOY/ref=ox_ya_oh_product).
*A $15 Taylor Candy Thermometer ( yah a candy thermometer)  I clip it to the side of my boil & jam it deep in the middle of the Tun.

I like them all.  I use 'em all.
I sort of,  kind of, pretty much think that I should use the expensive mercury thermometer as  my gold standard.  
It is a Fisher  ( woo hoo )  And after all mercury is a haz-mat that means it gotta be better.

The Polder unit has that nice slender cable that I can slip  under the Tun top without losing much steam/heat.
If I had to make do with just one I think I'd keep the Polder.   It's got a timer and  an alarm for temp and time. Both of which I really like.

If you asked me what I wanted for Christmas it wouldn't be another thermometer.







 
CR Do you check all of them against each other and adjust them?

Sometimes I wonder if it is consistency within a range, rather than dead on.

Thoughts people?
 
I have a yellow glass thermo I trust, and two digitals.  Calibrated all three at 0F and in 150F water.  The new digital is slower to respond but it gets there.  I calibrate the digitals to zero and they get to within 0.2F in the 150F range.  (The new digital is backup since I dropped the other one.) 

I hold a digital in the mash while I'm stirring in the grains and getting it to the desired mash temp.  Then I have a disk of that pink insulation board that sits on the mash to reduce heat loss, and I poked a hole in that to hold the glass thermo, which I insert deep enough so that about 145F and up is showing.  I can look in there without disturbing much and verify the mash temp hasn't slipped much. 
 
Rep said:
CR Do you check all of them against each other and adjust them?

Yah I have.  Just like people every one is different  The Polder and the mercury are pretty close, the Digital Taylor is pretty close too.


Sometimes I wonder if it is consistency within a range, rather than dead on.

I should think so but only  so long as the range is in the ball park.
As you know, if you get the tun temp too high, you kill the enzymes, too low, and you get diddly.


 
BeerSmith said:
Just out of curiosity - what's a weldless thermometer thingee??

A way to get a thermometer probe to pierce a wall whether it's the Tun or the Kettle.  It relies on seals either polymer or metal to metal.
 
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