General Thermometer Inquiry

[awoitte]

I feel like there aren't a whole lot of options on brew sites for different thermometers, specifically those that fit on and attach to kettles for things like mash temp and such. I've purchased a few different kinds but it seems like even through calibration they get thrown off, or a little splash and they get water in them.

I've got a few fermentors favorites (no longer sold on NB I believe)... Even if I just flick the metal a little the dial starts to get out of sync.

Does anyone have thermometers or a brand they swear by? I'm looking into purchasing several for my up and coming all grain build. The last thing I want to do is spend a bunch of money on the same thermometer only to find out they are junk like the last couple I've purchased.

Cheers! =)

 

[gfarantes]

I use the thermoworks chefalarm. It seems pretty good and very well built.

 

[MaxStout]

Those brew shop dial thermometers are not accurate enough for mash temps. And the 3" dial thermometers that thread onto kettles are only good enough to get you in the ballpark, but again, not accurate enough for mash, IMO. You can't go wrong with Thermoworks. Their Thermopen is superb, but a little pricey, at around $80. For about $20, this is the thermo I use. It works well, is accurate and fast-reading.

 

[TLaffey]

^ +1 on the Thermopen--fast and very accurate digital thermometer. I didn't realize what I was missing until I got one of them. I have a Brewmometer on the HLT. Check the calibration (and actual mash temp) with the Thermopen. Thermopen also perfect for BBQ.

One day I dropped the thermopen into my BK. Fished it out, washed it off, checked calibration with ice. Perfectly fine.

 

[day_trippr]

I love my classic Thermapen, bought it for my smoker and kitchen years ago and then found it useful for brewing.
But it's not the right thermometer for the mash - the probe is way too short.
This is much more useful http://www.thermoworks.com/RT610B-24
One can easily probe to the corners of a 20g MLT to check for cold spots, etc.

fwiw, I do have a Brewmometer on each of my kettles, each one calibrated at the temperature of interest (152°F for the HLT and MLT, 212°F for the BK) using my Thermapen as the reference...

Cheers!

 

[fragged]

Those brew shop dial thermometers are not accurate enough for mash temps. And the 3" dial thermometers that thread onto kettles are only good enough to get you in the ballpark, but again, not accurate enough for mash, IMO. You can't go wrong with Thermoworks. Their Thermopen is superb, but a little pricey, at around $80. For about $20, this is the thermo I use. It works well, is accurate and fast-reading.

Have to check the brand on mine, but I've never had an issue with my 3". I check it every few brews against a thermocouple (.5 C tolerance; what I used before adding a thermometer to kettle).


Edit: I should mention I've been considering a thermopen, mostly for cooking meats, but it would make checking my dial considerably easier.

 

[fragged]

Quick update, my dial says northern brewer on ot, not sure who makes thiers, but it's dead accurate throughout its range.

 

[MaxStout]

Quick update, my dial says northern brewer on ot, not sure who makes thiers, but it's dead accurate throughout its range.

You got a good one! The dial thermo I got with my initial brew kit is off a few degrees. I still have it, but it's been relegated to kitchen use.

 

[fragged]

One thing that occurred to me when I bought a few digital thermometers for around the house years back. One thermometers accuracy is only as good as the nexts. I bought 5 and it wasn't until I put them all in the same spot that I realized two were likely inaccurate (other three read the same temp).

For those saying one is more accurate than another, I'd wonder if you have at least three for comparison.

If only comparing two thermometer, you have to assume one is accurate to assume the other is not.

Boiling water is another method, but I see many people use the 212F/100c metric on that, which is only accurate at sea level. You have to adjust for your altitude beyond that. Talking about dials, that still only ensures they are accurate at boiling, not entire range (though based on how a decent dial works, it being accurate throughout if accurate at boiling is a safe bet).

I use a couple b thermocouples when I want to double check a thermometer.

 

[gfarantes]

I think ice+water is the best way to calibrate a thermometer.
http://www.thermoworks.com/thermapen101_creating_an_icebath

 

[ancientmariner52]

It's even worse than you think. Boiling temp is totally indepedent of altitude. You could be on the moon, or the Dead Sea, and altitude wouldn't have the tiniest effect.

The actual variable is atmospheric pressure. At sea level, average pressure is 14.686 psia and boiling temp is 212 deg F. But let the barometer go up or down, and it changes.

So boiling temp. is out, and ice is tricky to get an even temp. So what to do? Get a glass lab grade thermometer and use it to calibrate the rest. My lhbs has 'em for a whole 7 bucks.

So heat some water to about the temp. you are most interested in, prolly around 150 deg F. Stir it up real good, and place the lab thermometer and one of the ones you want to check. If it can be adjusted, do so. If not make a note of the amount and direction of the difference: +1.5°, -4°, whatever. Repeat until you're done. Keep stirring the water so the temp. remains uniform.

So now the ones you could adjust are calibrated. For the non adjustable ones, apply a sticker with the correction factor needed. If the error was -3°, the correction factor is +3°. Just mentally apply the c.f. when you take a reading. If it's good enough for thousands of steam plants, ashore and afloat, it'll do for home brew.

 

[Qhrumphf]

You can have a thermometer be accurate at boiling, accurate at freezing, and off in mash range.

There are multiple factors to the accuracy of equipment. There's the precision (how fine it reads), the accuracy range (how far off the reading is from actual), there's the repeatability and reproducability- ie will it always read the same way every time.

The issue is that most thermometers, cheap kitchen ones especially (as well as the cheap brew shop ones), have a wide accuracy range, often by several degrees. For meat cooking this sufficient- a reading of 165 meaning 163 vs 165 vs 167 often won't make or break you. However, for mashes, it very well can.

I had a thermometer, that was allegedly a lab thermometer (I found out later it actually wasn't) that was accurate at freezing and boiling, but read 3 degrees high in mash range- 147 was actually 144, 153 was actually 150, etc. It read consistently in all its ranges, but it was consistently wrong. And it turned out that the tolerance was quite wide on it.

This is where ACTUAL lab thermometers are useful- that range is very small. The Thermapen served me well at home for many, many years, because it's +/- 0.7 degree accuracy. They also sell a calibration thermometer that's slower and more expensive, but is more accurate than most lab grade thermometers, at +/-0.07. As indicated above, get a REAL thermometer and calibrate with it. Granted, the $7 buck "lab grade" LHBS thermometers I've seen that are advertised as such are where I've run into problems with not actually being up to spec. I'd look for a thermometer that's specifically certified by NIST or the like. And that's the nice thing about the Thermapen- it's cheaper than some of your certified lab thermometers (although certainly far from all of them), but is NIST certified.

I've also used a high grade waterproof thermocouple thermometer from Taylor that was as almost as accurate as the Thermapen (don't recall if it was NIST compliant though, don't think so), but with a submersible probe that was more practical than the short probe of the Thermapen, but was also like twice the price. Eventually got trashed under use/abuse and haven't had the cash to replace it.

If you look to industrial cooking suppliers, you can get relatively inexpensive kitchen thermometers that, while not overarchingly accurate in general, are designed to be accurate specifically in the food-safe cooking ranges, which will include typical mash and strike water ranges.

 

[ancientmariner52]

You are absolutely right. I couldn't possibly disagree with a word of it. What I was describing was a way to get, if not wholly accurate measurements, at least consistent measurements. I have a traceable lab grade thermometer. It is so old the markings are barely legible, and the tiny mercury column is nearly invisible to my tired old eyes. So I bought a new (cheap, French, not traceable) glass thermometer with a big fat red column that I can see.

I'm all about practically. The cheap thermometer is probably off a bit. But it will be off the same amount for as long as it exists. So it becomes my standard for all the rest of my working thermometers.

Am I explaining this clearly? What I'm after is practical, reliable, repeatable measurement. I don't need to match numbers with some arbitrary standard in Brussels or DC, just hit my own arbitrary numbers every time.

I totally respect the points you make. I just don't believe it's that critical for the average home brewery. I know it isn't for mine.

 

[Qhrumphf]

You are also correct. As with just about everything else in homebrewing, accuracy to whatever standard doesn't matter as long as it's consistent- IBU formulas are a perfect example. If 152 on your thermometer is too fermentable, up it to 154. Doesn't matter what the actual number is. As long as it's reliable to your equipment.

To the OP, if you really feel like going fancy and want to build things in to your equipment, RTD thermometers are incredibly accurate, they just tend to be pricey.

 

[eric19312]

I really like this thermometer.
https://www.brewhardware.com/product_p/cdndtq450.htm

Cheap enough that I’ve got 2 or 3 around the house so I don’t spend much time searching for it on brew day (it sees plenty of kitchen/outdoor cooking activity too). Dependable, sufficiently accurate and responsive. I buy them as stocking stuffers for non beer making friends and family too.