Lesson learned: Buy an accurate thermometer

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dmbsteve

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Other than the obvious essentials - mash tun, big pot & propane burner - an accurate thermometer should also be at the top of the list for must-have's when brewing all-grain. I learned this the hard way.

I have two dial thermometers. I assumed both were accurate, so I have used both interchangeably since I went to all grain a few months ago. But I discovered during my last batch, that one of my thermometers reads about 12-15 deg low. I first noticed this after I had brought my sparge water to a boil (I had left the room for a while and left the burner on high), but the thermometer was only reading about 200 deg. I don't live in the mountains or anything, so I know my water boils at 212. I then realized that my mash temp must have been way too high, because I had overshot it to begin with by a couple of degrees, and if the thermometer was reading low, then the mash temp theoretically could have been as high as 170 deg. That was a week ago and I've been worried about it ever since. The airlock bubbled for a couple of days, but didn't seem as vigorous as usual. I'm concerned that I will have very low ABV and possibly some astringent flavors. But I will let it roll and see how it tastes.

My next purchase will be an accurate thermometer, but I don't want to spend a fortune on one. Walmart and Target sell the instant read digital thermometers (like you use for meat and such) for about 10 bucks. Would one like this be OK?

http://www.walmart.com/ip/Taylor-TruTemp-Digital-Instant-Read-Thermometer/16541966
 
For what its worth, I go low tech with a floating thermometer like this one and it works great. Accurate and convenient.

thermometer.jpg
 
Even a cheap thermo will work as long as you have some way to calibrate it.

I've been fine using a $10 cheese thermometer calibrated at mash temps using lab grade instruments at my job.

Even the expensive thermos need calibrated every now and then. Unfortunately, the only way for most to accomplish this is to send it out to the manufacturer, or find a local calibrations company.
 
mcaple1 said:
thermapen.....'nuff said!
Click to expand...

THIS. When I went AG, I had read enough threads on this forum to convince me I didn't want any bargain digital thermometers. I got a Thermapen, an have never looked back. It's also useful in other applications (I bake a lot), and is worth the $100 just because of how fast it delivers an accurate reading.

The closest analogy is optics, where you just -can't- get results with cheap glass. Get a $75 set of cheap no-name binoculars. Then pick up a $250 Pentax binocular- you will go "wow." Then pick up some $1000 Steiners, you will think you're looking at another world.
 
I'd recommend anything by Thermoworks. I went with this one:

RT600C-Mock_489x275.jpg


I got it from Amazon for ~$25 and it works great. It's much cheaper than a Thermapen, but made by the same company so the quality is still there.
 
Pappers_ said:
For what its worth, I go low tech with a floating thermometer like this one and it works great. Accurate and convenient.

thermometer.jpg
Click to expand...

this is not accurate enough, especially when 5 degrees can make a big difference in your mash
 
I use a Fluke handheld with probes mounted in my mashtun and water tank. I send it out with the ones at work at regular intervals to be calibrated. Very accurate down to tenths.
 
I like to brew with at least two, for a spare, to check different areas of the mash, and as a check on your other thermometer. That is the way i figured out that my really nice thermometer quit working right and was reading 15 degrees hot.
 
This is super cheap at the moment. Not as fast as Thermapen, but it is accurate.
 
Last edited by a moderator:
Samc and Flabyboy -

Do you happen to use a pot clip with your thermometer? If so, where did you find that as well?

Thanks!
 
Cdn quick read all the way. The Pro Accurate. $15.approx. No way I'd pay $100+ for something I could drop and break like the thermapen.
 
I've killed 2 $15 digi quick reads from walmart and target. Now I'm getting a cheap probe thermometer from the LHBS ($25) should be much harder to break.
 
+1 for thermapen. it's kind of absurdly expensive for a thermometer... I know... but after you've used it for 6 months and experienced the difference between a cheapie consumer digital thermometer and a seriously professional tool... I think you'll feel justified in the expense, even if your significant other doesn't get it... lol
 
thegerm said:
+1 for thermapen. it's kind of absurdly expensive for a thermometer... I know... but after you've used it for 6 months and experienced the difference between a cheapie consumer digital thermometer and a seriously professional tool... I think you'll feel justified in the expense, even if your significant other doesn't get it... lol
Click to expand...

I got one as a gift and I couldn't go back. If it breaks I'll buy myself a new one. It's seriously that much better. I actually trust it to be correct within a couple seconds.
 
I am sending back my second CDN DTQ450X ProAccurate.
Bought on amazon. First one didn't make it thru my first brew and stopped working. The Temp would start at room temp and then count down and never stopped.
The second one after several calibrations was completely inaccurate above 140 deg and stayed about 15 deg below boiling when the water was clearly boiling in the kettle.
I bought the CDN because of the great reviews here. But so far they have been completely unreliable.
I can't justify spending $100. But 20 to 30 is acceptable if it is accurate and I can calibrate it.
 
nate456789 said:
I am sending back my second CDN DTQ450X ProAccurate.
Bought on amazon. First one didn't make it thru my first brew and stopped working. The Temp would start at room temp and then count down and never stopped.
The second one after several calibrations was completely inaccurate above 140 deg and stayed about 15 deg below boiling when the water was clearly boiling in the kettle.
I bought the CDN because of the great reviews here. But so far they have been completely unreliable.
I can't justify spending $100. But 20 to 30 is acceptable if it is accurate and I can calibrate it.
Click to expand...

That sucks. I calibrated mine in a glass of slushy ice water and it has been super accurate and fast. Sorry it didn't work for you
 
EarthBound said:
I believe the most critical part of homebrewing is maintaining accurate mash temps.

That being said... Thermapen, FTW!
Click to expand...

At which you cannot calibrate in cold or boiling water. Thermometers are not always linear, so its false to assume that a thermometer calibrated at roughly 32 is also accurate at 150.
 
I got my thermapen about 5 months ago for brewing and bbq. After going through about 5 different brewing thermometers in the last couple years I am so happy to have the thermapen. Before that I used a $5 lab thermometer from my LHBS. Accurate but not fast and it was also made of glass (I broke one of them)
 
After some erratic results with the past brews, I discovered my Candy Thermometer believed water boiled at 195F. Time to upgrade I suppose...
 
Agent said:
After some erratic results with the past brews, I discovered my Candy Thermometer believed water boiled at 195F. Time to upgrade I suppose...
Click to expand...

It may be accurate if you are in the mountains
 
Spot on thegerm.
It probably didn't help that I usually mash in the mid to upper 150's.
New thermometer tells me water boils at 204 Degrees. I'm looking forward to trying it out this weekend.
 
thegerm said:
2 quick google searches say gillette is at 1402 meters, and that the boiling point at that altitude is 203.7.
Click to expand...

So much for that idea. Lol
 
After reading the posts, I went with the CDN quick read..$11 bucks on Amazon!

Love it! Quick..accurate, consistent, and durable...I've already dropped the thing twice on the porcelain tile kitchen floor. Each time I was pissed because it had slipped out of my pocket (was wearing gym shorts with really shallow pockets) and was sure I had broke it. But it fired right back up and still read perfectly. Note to self: do not wear those shorts anymore while brewing...
 
I have the CDN as well, been using it for about a year with absolutely no problems. Quick and accurate. Bummer that some have received lemons :(
 
I just epoxied where the probe and wire meet on my digital thermometer from wallmart. seems to have done the trick as i know of others who complained about thermometers going bad after getting wet where wired at probe
 

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