What kind of Mash temp thermometer?

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Tmeister

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hey, im a all grain brewer with about 10 brews on my belt. I allways use a probe thermometer (the ones with the circular dial and probe) for checking mash temp, and strike water temp. I allways get worried with these because I feel like they aren't that accurate. I do calibrate my thermometer, but it just worries me.
My question is... how do you experienced AG brewers check strike and mash temp. ? Is there really nice thermometers to use or is what im using just fine.
I haven't had any problems with temp normally besides just slight variation, I just want to be exact.
 
I've always used one of the regular mercury lab thermometers they sell at the home brew store, but a few days ago I saw a digital thermometer with remote probe (and alarms and such) at Lowe's for $20, so I grabbed it. It was in the turkey/outdoor grilling section.

I haven't used it or checked it for accuracy yet, but the probe plugs in with a regular mono mini headphone plug, so my plan is to use a headphone splitter from Radio Shack so it can feed the display and some sort of op-amp circuit I could build to control a heater element at a given setpoint (using a trim pot to match whatever voltage the probe sends when the display says I'm at the right temperature).
 
411TTK6Y5TL._SL500_AA280_.jpg


Taylor 9842 Commercial Waterproof Digital Thermometer

Has survived a few drops into the wort
 
Tmeister said:
hey, im a all grain brewer with about 10 brews on my belt. I allways use a probe thermometer (the ones with the circular dial and probe) for checking mash temp, and strike water temp. I allways get worried with these because I feel like they aren't that accurate. I do calibrate my thermometer, but it just worries me.
My question is... how do you experienced AG brewers check strike and mash temp. ? Is there really nice thermometers to use or is what im using just fine.
I haven't had any problems with temp normally besides just slight variation, I just want to be exact.
Click to expand...

Any calibrated thermometer is good. Some of the digital thermometers may be off unless calibrated. A glass lab thermometer is the standard and the one I trust, and the one used to calibrate all the others to.
 
I use one of these. Inexpensive, relatively rugged, and accurate.

31Q3X4DHKVL._SS500_.jpg
 
babalu87 said:
411TTK6Y5TL._SL500_AA280_.jpg


Taylor 9842 Commercial Waterproof Digital Thermometer

Has survived a few drops into the wort
Click to expand...

I use this as well. Picked it up after breaking my third floating thermometer. Calibration is dead on and can be adjusted if necessary. I've dropped it into near boiling wort once with no problems. I think it was like $13 at local kitchen supply store.
 
I got a brand-new "digital wine thermometer" at the local Goodwill for $2.99. I took it out of the package, and discovered that the temp range was -40F to +300F, and I couldn't get to the front of the store fast enough!

I've calibrated it against three other thermometers in my house, and have a pretty good idea of just how spot-on it is. Best $3 I've ever spent!
 
Thanks a lot for all the suggestions, I like the waterproof Taylor one. Maybe il even buy a glass lab thermometer and throw that in the mash.
 
gturner6ppc said:
I've always used one of the regular mercury lab thermometers they sell at the home brew store, but a few days ago I saw a digital thermometer with remote probe (and alarms and such) at Lowe's for $20, so I grabbed it. It was in the turkey/outdoor grilling section.

I haven't used it or checked it for accuracy yet, but the probe plugs in with a regular mono mini headphone plug, so my plan is to use a headphone splitter from Radio Shack so it can feed the display and some sort of op-amp circuit I could build to control a heater element at a given setpoint (using a trim pot to match whatever voltage the probe sends when the display says I'm at the right temperature).
Click to expand...


Beware of those cheapies over the long haul. If you look at the tip of the probe you will likely see a seam between the point and the shaft, this is where liquid can seep in over time and absolutely bugger your thermo! Many of the cooking thermometers are not designed for immersion in liquids.

It will likely work for a period of time, but one day it will crap out, or worse it will read +20 or -20 and cause you a 5 gallon batch of headache.
 
Yuri_Rage said:
www.thermapen.com. You won't regret it.
Click to expand...


I want one of those so bad! Can't quite justify the expense, though... even though the original models are now down to $74.

The digital pen thermo I bought at Target for $10 works great, much better than any of the probe thermos that I've used. Just wish it gave a faster reading.

Those thermapens are basically instant-reads, aren't they?
 
the_bird said:
I want one of those so bad! Can't quite justify the expense, though... even though the original models are now down to $74.

The digital pen thermo I bought at Target for $10 works great, much better than any of the probe thermos that I've used. Just wish it gave a faster reading.

Those thermapens are basically instant-reads, aren't they?
Click to expand...

I've tried just about every consumer-grade thermometer, then finally gave up and got a Thermapen.
It reads almost instantly and I know that the reading is accurate.
The others were off by several degrees.
I still use the ones with the audible alarm, but I make sure the alarm goes off early, then check with the Thermapen.
 
UnderDogs said:
Has anyone else used this thermometer? It looks like the price is right so I just want to get some more opinions before I spend the money.
Click to expand...

I use the same one and it's great. It is fairly quick and can be calibrated. (I've never found the calibration necessary. It was accurate when I got it, and has never varied.)


-a.
 
The Williams thermo looks pretty interesting, and you are right, the price is certainly right...but I wonder how it can calibrate accurately using just one point:

"to calibrate, place it in a crushed ice solution, and press the calibration button. Within seconds, it has calibrated itself to 32° F. (the temperature of a crushed ice and water solution)."
even if it is a platinum RTD sensor and dead linear (as PRTDs are), one would think it needs a second point to accurately calibrate.

Ah, what the heck. I guess I am overthinking and trying to inject NIST-trace laboratory practice out of embedded habit.
 
UnderDogs said:
Has anyone else used this thermometer? It looks like the price is right so I just want to get some more opinions before I spend the money.
Click to expand...

I used that one and it seemed great for awhile...until the other day when it just seemed off somehow. I recalibrated it at freezing, but it remained off by several degress at the upper end. I calibrated it at boiling but it was off by several degrees at the bottom end. Previously it would be correct at both ends of the spectrum.

I tossed it and my Thermapen is on the Fedex truck Out For Delivery as I type.
 
I just bought (2) Comark DT400 thermometers.

+-1F and calibratable.

They were about $25 each and have long probes.

FWIW the $5 Taylor digitals that I bought years ago, are only off 1F at 32F and 1F at 210F...

I feel a little better having calibratable thermometers though. They also have MAX temp. memory so that you can go back and see how hot they have gotten since the last reset.

I will use one to verify my MLT temp. when running the HERMS, the other will be for yeast work and coffee making.

Calibrated at 32F in a 60% ice slurry, the (2) therms read .5F different at boiling.

DT400.jpg
 
I 'wort-proofed' and use a Taylor digital meat thermometer almost just like the one in this thread. One of the things I like about it is that I can easily use it for monitoring keezer/lagerator temps and just leave them attached to the side of the fridge/keezer (they have magnets on the back). And I can leave the probe in the water bath for fermenting lagers. Not calibrate-able though.

After many brews I decided to disassemble and clean. Upon reassembling I found it much easier to just carefully pull the thermocouple wire out of the stainless probe, slide the tubing over the wire, then put the probe back on and slide the tubing back over the end of the probe and o-ring ( I only use one, internal o-ring and it has never leaked).

I have a non-water-proof digital similar to the Thermapen but I end up just using it for verification. The probe just seems easier to use. YMMV.
 
Bigsnake said:
I use a Traceable Water-Proof Thermometer. After killing my digital kitchen thermometer just from heavy steam contact I decided I wanted to definately go water-proof. It's nice knowing I don't have to worry about getting it wet. http://www.control3.com/4039p.htm
Click to expand...
Got one of these, but have to agree with Evan!, I've Had it With These POS Traceable Thermometers! Mine is now totally unreliable also. It might be good for something, but doesn't stand up to brewing.
 
I went with a Taylor thermo, like others. Being an engineer, I got the specs --plenty accurage enough for mashing, so there is no need for anything more expensive. Mine was actually the digital wine themometer, but the water proof one would be better.

I see all these people willing to spend a bundle on a themopen or other such expensive device, but IMHO, it's not necessary today if you get a name brand and check the specs. That probably wasn't as true years ago, but digital thermos are pretty accurate today.
 
RichBenn said:
but digital thermos are pretty accurate today.
Click to expand...

You are insane - seriously. I even have a Platinum RTD that is reading off 5-10 degrees. In fact, I have FOUR RTD's by the same manufacturer and two of them read off by several degrees. I then have FOUR additional thermometers... two glass scientific, an instant thermopen, and the thermocouple from Ideal. Only four of these eight temperature sensors read the same.
 
Well,

I just made me a copper-constantan thermocouple today for my pot. Just open wires with solder (lead free I am sure) and calibrated it to use for steeping and PM batches. Should be fun and easy to use with a multimeter. I will be checking against thermometer at home, but I calibrated it to a lab one.

Thermocouples are fun :ban:

I may try to make a stainless steel thermowell in the future. Weldless I am sure.
 
JVD_X said:
You are insane - seriously. I even have a Platinum RTD that is reading off 5-10 degrees. In fact, I have FOUR RTD's by the same manufacturer and two of them read off by several degrees. I then have FOUR additional thermometers... two glass scientific, an instant thermopen, and the thermocouple from Ideal. Only four of these eight temperature sensors read the same.
Click to expand...

RTD's are not necessarily that accurate. It's old technology. I used to design interfaces for them for high speed data aquisition. They were liked, IMHO, because they produce a linear relationship between temperature and resistance, and they were rugged in industrial applications and you could do long, remote lead lengths with 3 and 4 wire systems. Easy to design for for most applications, where +/- 5 degree absolute accuracy is more than good enough. One can get better accuracy, but platinum is not cheap and 4 wire versions are a bit more pricy.

In my mind, thermocouples fall into the same category. are a bit cheaper for the device, but with more compensation circuitry needed.

The new "cheap" digital thermometers use thermistors. The device is anything but linear, and they are slow to respond(8 seconds) but the integrated circuits that compensate cost next to nothing today and are very accurate. The two I have are accurate to less than a degree at 32F (ice bath) and 212F (boiling water). The resolution is .1 degree F. Plenty good enough for my needs. If you look, it's not at all hard to find ones with .5 degree NSF accuracy, if you want one you can count on.

They aren't designed for industrial applications and don't really work well for remote applications(long wiring) But because of quantity, (the use in home medical thermometers and the like) the cost has gone WAY down and the performance way up. If they break, it's not much to replace them. Buy more expensive stuff if you like, but I won't.
 
RichBenn said:
. . . but they integrated circuits that compensate cost next to nothing today and are very accurate. The two I have are accurate to less than a degree at 32F (ice bath) and 212F (boiling water).
Click to expand...
It's nice to have comments from someone in the industry. This leads to the question, what two (make/model) are you referring to? What do you think of the Comark DT400 that Pol mentioned above?
 
RichBenn said:
RTD's are not necessarily that accurate. It's old technology. I used to design interfaces for them for high speed data aquisition. They were liked, IMHO, because they produce a linear relationship between temperature and resistance, and they were rugged in industrial applications and you could do long, remote lead lengths with 3 and 4 wire systems. Easy to design for for most applications, where +/- 5 degree absolute accuracy is more than good enough. One can get better accuracy, but platinum is not cheap and 4 wire versions are a bit more pricey.
Click to expand...

Huh? Not to be argumentative, but my experiences with PRTDs were quite different than yours. Like you, I designed and implemented DACs - for laboratories and manufacturing settings in situations where temperature knowledge was critical to our control processes.

The industry standard for platinum RTD's according to DIN IEC-751 is Class A or B, that is, a typical accuracy for Class A ±0.15°C at 0°C, and ±0.35°C at 100°C, with ±0.3°C at 0°C, and ±0.8°C at 100°C in a Class B setting. This is quite good when compared to the ±2.2°C of a standard Type J or K thermocouple. And as you state, the DFL - dead frakking linear.

You may recall accuracy:

Class A: Dt °C = ± ( 0.15 + 0.002 • | t | )
Class B: Dt °C = ± ( 0.30 + 0.005 • | t | )

where: | t | = absolute value of temperature in °C

As for two-wire versus four wire, the two wire setting is subsceptible to resistance changes in the lead wires and/or connections, whereas the resistor bridge in a four wire setting offsets and nulls that out. I never bothered with two wire setups, given the ease of implementing four-wire.

Another reason the PRTDs are well liked in industrial and laboratory conditions is that cycle to cycle differences normally can’t be measured and are considered lumped into stability specifications. Further, you can typically you can count on the probes to be almost totally non-reactive. Some J and K thermos were pretty weak in that regard and were not long lasting. Not only that, they tend to require relatively constant calibration in my experience.
 
ForRealBeer said:
Huh? Not to be argumentative, but my experiences with PRTDs were quite different than yours. Like you, I designed and implemented DACs - for laboratories and manufacturing settings in situations where temperature knowledge was critical to our control processes.

The industry standard for platinum RTD's according to DIN IEC-751 is Class A or B, that is, a typical accuracy for Class A ±0.15°C at 0°C, and ±0.35°C at 100°C, with ±0.3°C at 0°C, and ±0.8°C at 100°C in a Class B setting. This is quite good when compared to the ±2.2°C of a standard Type J or K thermocouple. And as you state, the DFL - dead frakking linear.

You may recall accuracy:

Class A: Dt °C = ± ( 0.15 + 0.002 • | t | )
Class B: Dt °C = ± ( 0.30 + 0.005 • | t | )

where: | t | = absolute value of temperature in °C

As for two-wire versus four wire, the two wire setting is subsceptible to resistance changes in the lead wires and/or connections, whereas the resistor bridge in a four wire setting offsets and nulls that out. I never bothered with two wire setups, given the ease of implementing four-wire.

Another reason the PRTDs are well liked in industrial and laboratory conditions is that cycle to cycle differences normally can’t be measured and are considered lumped into stability specifications. Further, you can typically you can count on the probes to be almost totally non-reactive. Some J and K thermos were pretty weak in that regard and were not long lasting. Not only that, they tend to require relatively constant calibration in my experience.
Click to expand...
I agree RTDs are better than thermocouples. The poster I was replying to was getting terrible results with his RTDs, which were probably either faulty or the resistance measurement circuit is bad, or ???

When I designed circuitry, it was such that it would have a margin of error good enough for the worst case component aging over a 5-10 year period and at a cost as low as possible while still meeting the needs. So even though the RTD itself might be highly accurate, the rest of the system might be far less, including the tolerances and aging of the resistors, transistors and capacitors used to measure the resistance to the thermal coupling of the RTD or thermocouple to the product being measured. But it depends upon the application. My products were in the turbo-machinery field, measuring case and bearing temperatures. A few degrees was good enough. Alot of process control requires much better accuracy than I would typically be required to deisgn for.

My point, and I was hoping to not get into much detail, was that cheap thermistors are OK for our application (home brewing, not professional process control), not to argue the merits of RTDs vs. thermocouples.

For 140-180 degrees, in the range where we mash, a thermistor device can very easily have .5 degree F resolution for $20. Here is one example here:

Taylor USA

although there are many more.
 
Rich, agreed about thermistors. Like I said, I absolutely am not trying to be argumentative, but as you might have guessed, electrical engineering and instrumentation are real passions of mine. You and I could probably have some very interesting discussions about these things between the two of us over a couple of our homebrews... but the average reader here would lose interest quickly. What the heck, use the best stuff you can afford, do it the best you can and enjoy the beer. It'll be good.

Also, please let me say I hear 100% about what you are saying about cost containment in your work. I was lucky in that in my company's heading days of Big R and little D for stuff coming out of blue sky, we tended to have bigger budgets and in the case of materials engineering we were doing, no corners were turned. Nowadays, we're as cheap as anyone and I am the curmudgeon in the corner saying "are you sure that what you measured is accurate?"

Anyhow, Happy Thanksgiving and look forward to talking to you about this some more sometime.
 
AnOldUR said:
It's nice to have comments from someone in the industry. This leads to the question, what two (make/model) are you referring to? What do you think of the Comark DT400 that Pol mentioned above?
Click to expand...

I'm using primarily a cheap Taylor wine thermometer, but have other cheap thermistor based products I use around the home.

The product you reference seems to have a 1 degree F accuracy. If the repeatability is good, then it seems good enough for me, although maybe not for others. The parent company of Comark is Fluke, which had a good reputation, AFAIK. But no experience at all with this product or Comark.

Hey, and for anyone else that wants to argue the merits of more expensive vs. cheap measuring devices -- this is my opinion and what works for me, a guy on a budget who likes deals. Alot of people have different values, like having the best, and I have little doubt the Thermopen is a better device.

Reliability? I think there are other threads here that one may want to peruse for user experiences with various devices.

Rich
 
ForRealBeer said:
Rich, agreed about thermistors. Like I said, I absolutely am not trying to be argumentative, but as you might have guessed, electrical engineering and instrumentation are real passions of mine. You and I could probably have some very interesting discussions about these things between the two of us over a couple of our homebrews... but the average reader here would lose interest quickly. What the heck, use the best stuff you can afford, do it the best you can and enjoy the beer. It'll be good.

Also, please let me say I hear 100% about what you are saying about cost containment in your work. I was lucky in that in my company's heading days of Big R and little D for stuff coming out of blue sky, we tended to have bigger budgets and in the case of materials engineering we were doing, no corners were turned. Nowadays, we're as cheap as anyone and I am the curmudgeon in the corner saying "are you sure that what you measured is accurate?"

Anyhow, Happy Thanksgiving and look forward to talking to you about this some more sometime.
Click to expand...

The same to you!:mug:
 

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