What Thermometer can i trust?

I currently have two thermomters. Your basic Thermoworks and a CDN Quicktip.

I calibrated the CDN in crushed ice with water and tested them both and they both read 32. Today I brewed and measured the mash temp, the Thermo read 156 and the CDN read 153. later when i tested the OG of the wort, i took another reading and the Thermo read 68 and the CDN 67.

I guess these aren't that far off, but im not sure which thermometer to trust and im not sure if i mashed at 153 or 156. I was really hoping to nail down my process and the temp of the mash seems to be a variable.

Any ideas or should I just RDWHAHB?

Ethanol and water boils at 172F at sea level and you're probably close. A much better calibration point for mashing.

get a lab thermometer. They are only $6 at my LHBS but its the only thing I trust anymore. I broke it the other day while transporting my brew gear, but at $6, its nothing I am going to loose any sleep over.

I just got one of these at TJ Maxx for $13.00 http://www.oxo.com/OA_HTML/xxoxo_ib...=10062&item=75056&minisite=10024&respid=53057

I tested it in ice water and it was spot on.

Both of mine seemed spot on in ice water too. Are the floating thermometers as reliable as the lab thermometers? I have one of those.

I guess ill test them both again with boiling water. im only about 500 feet above sea level.

I have three Taylor's They are almost perfect, I have one that reads 1 degree high and one that reads 1 low. I put all thee in ice water and brought it to a boil they stayed consistent through the entire time 0-212 with the other two reading 1 high and low across the entire range

Ice bath temp should be 34F as it is changing phase.

Ice bath temp should be 32F as it is changing phase.

david_42 said:

Ethanol and water boils at 172F at sea level and you're probably close. A much better calibration point for mashing.

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+1. All of you ice calibrator folks should keep this in mind. Why focus the precision near freezing? Mash is at 150 or so. If you don't do ethanol and water, boiling water calibrations are still closer to intended mash temps.

What mixture of ethanol and water would one use? Also, how would you figure in altitude to the 172°F?

jamesnsw said:

What mixture of ethanol and water would one use? Also, how would you figure in altitude to the 172°F?

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and can you drink it after?

jamesnsw said:

What mixture of ethanol and water would one use? Also, how would you figure in altitude to the 172°F?

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That's a good question. I calibrate with boiling water. But, I've read that ethanol, not a water mixture of it, boils at 172F. As for the mixture of ethanol and water, perhaps David_42 can chime in again.

cpbergie said:

Both of mine seemed spot on in ice water too. Are the floating thermometers as reliable as the lab thermometers? I have one of those.

I guess ill test them both again with boiling water. im only about 500 feet above sea level.

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I have found the floating thermometers to be extremely inaccurate. Mine reads at least 5 degrees wrong all the time and sometimes more. It's a useless piece of junk that screwed up many of my mashes until I realized this.

Thanks. And just for the record, I was calibrating at freezing because that was the only option for that particular thermometer.

jmo88 said:

That's a good question. I calibrate with boiling water. But, I've read that ethanol, not a water mixture of it, boils at 172F. As for the mixture of ethanol and water, perhaps David_42 can chime in again.

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Basically what happens is the boiling point changes depending upon the concentration of ethanol in the water. That's how distillation works. Pure ethanol boils around 172F, but a mixture is going to boil at a higher temperature, and as it vaporizes that temperature will change.

jmo88 said:

That's a good question. I calibrate with boiling water. But, I've read that ethanol, not a water mixture of it, boils at 172F. As for the mixture of ethanol and water, perhaps David_42 can chime in again.

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I was actually curious about this so I dug around a bit. If you can get 192 proof, then it will boil at 172 deg F. If you're something less concentrated then the boiling point starts to rise, and eventually approaches 212 deg F with 0% alcohol. According to this:
http://www.biofuelvaportechnologies.com/files/Azeutruic_distillation_of_ethanol.pdf
I think you might be able to get away with cheap 80 proof vodka (40% alcohol by vol), which should have a boiling point of 183.2 deg F. However the boiling point will start to rise once the ethanol begins to boil away (bc/the concentration of alcohol will start to go down) so I'd guess that once you see bubbles, do your calibration quickly.

Here's a calculator for reduced pressure, but it's only good for water, pure alcohol and an azeotrope mix.

jmo88 said:

That's a good question. I calibrate with boiling water. But, I've read that ethanol, not a water mixture of it, boils at 172F. As for the mixture of ethanol and water, perhaps David_42 can chime in again.

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How do you calibrate at boiling?

How do you calibrate at 172F?

I have only seen thermometers that calibrate at 32F in a 60% slush 30% water meduim.

I am sure you can see how far off they are at say boiling or 172F, is that what you mean?

cpbergie said:

Thanks. And just for the record, I was calibrating at freezing because that was the only option for that particular thermometer.

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That is the only option I have seen for ANY thermometer... ?

The expensive Thermapen allows for calibration at both 32F and 212F. But at close to $100, it should also be able to wash my car. :cross:

jeffmeh said:

The expensive Thermapen allows for calibration at both 32F and 212F. But at close to $100, it should also be able to wash my car. :cross:

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So you can calibrate at 212? That is awesome, except wouldnt youd have to calibrate it at SLP too for it to be accurate??

The Pol said:

So you can calibrate at 212? That is awesome, except wouldnt youd have to calibrate it at SLP too for it to be accurate??

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I am pretty close to sea level, lol. Actually, you can calculate the boiling point at your altitude, and calibrate it to that temperature. It has two calibration screws for using two reference points, but I do not know whether it would support using the upper one to calibrate somewhere around mash or hlt temperature.

I would expect it to be highly likely that if it is accurate at 32F and 212F then it would be accurate within that range, but it is certainly possible that there could be some variation.

I know you can find #s for what temp you are boiling at, at your elevation (pressure)... but if I hit the calibration button and it calls it 212F and I am only boiling at 210F (due to elevation and pressure), then the calibration is 2F off.

I calibrate mine at 32F in a 60% ice 30% water slush, and at BOILING (not 212) they are .5F off.

The Pol said:

That is the only option I have seen for ANY thermometer... ?

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This is the first I've heard that you can't calibrate at boiling. Why? I calibrated mine in a water and ice mixture and it showed I was boiling at 202F. So I calibrated it so I was showing boiling at 212F. I really don't understand the problem here.

jmo88 said:

This is the first I've heard that you can't calibrate at boiling. Why? I calibrated mine in a water and ice mixture and it showed I was boiling at 202F. So I calibrated it so I was showing boiling at 212F. I really don't understand the problem here.

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Are you using a digital?

The thermometers that I see most people using, when you push "calibrate" it sets that temp. to a constant. Typically 32F for a slush solution.

So if I place it in a glass of ice water press "calibrate" it calls that ice water 32F. I can place it in a glass of 40F water and press "calibrate" and it calls it 32F too.

If a Thermapen (mentioned above) calibrates at 32F and 212F... well, if my water is boiling on the stove, it isnt 212F... because I am not at sea level. SO if I place the thermometer in that boiling 210F water, press "calibrate", it will call that temp. 212F, which it is not. It is 2F off.

32F is not affected by pressure, so it is a pretty good #. 172F for the boiling of ethanol is great too, but wont work for a digital thermometer that most people use because you cannot calibrate to 172F

You are thinking analog, I am thinking digital

Simple.

jeffmeh said:

I am pretty close to sea level, lol. Actually, you can calculate the boiling point at your altitude, and calibrate it to that temperature. It has two calibration screws for using two reference points, but I do not know whether it would support using the upper one to calibrate somewhere around mash or hlt temperature.

I would expect it to be highly likely that if it is accurate at 32F and 212F then it would be accurate within that range, but it is certainly possible that there could be some variation.

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Oh, so it calibrates at ANY temp? I dont get it. Do YOU choose the temp, or does it just calibrate at say 32 and 212?

If I boil at 209F, can I have it call MY boil 209F then?

jeffmeh said:

The expensive Thermapen allows for calibration at both 32F and 212F. But at close to $100, it should also be able to wash my car. :cross:

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This is what confuses me...

Most thermometers with a calibrate with a push button. When you push that button, it calls whatever that temp. it is sensing, say 32F. I cant tell it to call it 40F.

So, if I boil at 209F, can I place it in a boil and calibrate it to 209F, or will it call it 212F?

EDIT: I have been trying to research how the Thermapen calibrates, and all I have found is that it uses a calibration trim button to fine tune at a single temp. (thier example was ice bath)

This may be useful if it is a TRIM, you could place it ina boil, if you know you boil at 209F, then trim the reading to that... that would work.

EDIT: That is how the Thermapen works, it has a ZERO and SPAN screw. Placed in ice water you adjust the ZERO trim to 32F. Placed in BOILING water you then adjust the SPAN to (212F) or whatever temp. your water boils.

I like the trim idea, that is nice. For $100 though, I will keep the ones I have as they are only off .5F at boiling and dead on 32F for $28

The Pol said:

This is what confuses me...

Most thermometers with a calibrate with a push button. When you push that button, it calls whatever that temp. it is sensing, say 32F. I cant tell it to call it 40F.

So, if I boil at 209F, can I place it in a boil and calibrate it to 209F, or will it call it 212F?

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These have two calibration screws. Lets say that I know the water is at 209F. Then I would turn the upper range calibration screw until the digital display reads 209F.

jeffmeh said:

These have two calibration screws. Lets say that I know the water is at 209F. Then I would turn the upper range calibration screw until the digital display reads 209F.

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Yah, see my edit above.

I use the Thermapen in the kitchen, as I do not have the new splash proof model, and it started to get a little flaky when I was using it for brewing.

I ended up getting one of these http://www.thermoworks.com/products/handheld/mtc.html for brewing with their 113-372-T type K wire probe. I have been very happy with it, and there are a huge variety of type K probes available. On Thanksgiving, it was certainly much more accurate with the oil in the turkey fryer than the analog that came with it. The handheld will go up to 1999F, but the probe is only good to 482F, lol.

The Pol said:

This is what confuses me...

Most thermometers with a calibrate with a push button. When you push that button, it calls whatever that temp. it is sensing, say 32F. I cant tell it to call it 40F.

So, if I boil at 209F, can I place it in a boil and calibrate it to 209F, or will it call it 212F?

EDIT: I have been trying to research how the Thermapen calibrates, and all I have found is that it uses a calibration trim button to fine tune at a single temp. (thier example was ice bath)

This may be useful if it is a TRIM, you could place it ina boil, if you know you boil at 209F, then trim the reading to that... that would work.

EDIT: That is how the Thermapen works, it has a ZERO and SPAN screw. Placed in ice water you adjust the ZERO trim to 32F. Placed in BOILING water you then adjust the SPAN to (212F) or whatever temp. your water boils.

I like the trim idea, that is nice. For $100 though, I will keep the ones I have as they are only off .5F at boiling and dead on 32F for $28

Click to expand...

I agree that if it works at that price then by all means go for it. I bought the thermapen before I started brewing, as I had gone through 5 $25-$40 digital thermometers and I was getting tired of replacing them. Cooks Illustrated gave the thermapen top reviews, so I figured I would spend a little more for something that presumably would not be junk. How long have you been using yours? I plan on converting a couple of coolers to go all-grain, and maybe I will give these a shot.

My thermoworks came with a calibration certificiation from NIST. My thermoworks pen exactly matches my lab thermometer, so... I trust my thermowork.

This web page shows 90-100% Isopropyl Alcohol boils at 180*F or 82*C

http://www.jtbaker.com/msds/englishhtml/i8840.htm

This would be much cheaper than boiling consumable ethanol

A mixture of 50% or greater alcohol to water is flamable and boiling alcohol over an open flame is extremely dangerous.

http://en.wikipedia.org/wiki/Ethanol

this wikipedia site show ethanols boiling point at 173*F

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItemVersion&item=300344845981&view=all&tid=385695517020

what do you guys think of this thermometer? it has 3 ft long waterproof sensor cable which could be inside the mash tun.....

I'm worried about 2% deviation. Is it too much?

I use the Taylor 9842



and it has a calibration screw with a relatively small range. IOW, not all digitals that have calibration do it via a fixed temp calibration "button".

I was thinking I'd prefer the CDN version because it does have an auto calibrate but I can see the problem there. I just with the taylor had a hold button.

I picked up this one for the Turkey as my thermapen was missing I found it the as I was brining the Turkey
I checked it with the Thermapen and its really dead on in all ranges . $14.95 at Lowes was cheap so I am going to keep it.

Hello everyone,
With all this talk about calibration of thermometers I went out and found a few tools that might be helpful to everyone:
Current barometric-pressure map
and this
Calculator
be mind full you will need to know your current elevation to get accurate results at the time of calibration.
Also note that the boiling point of water changes almost daily/hourly due to the current barometric pressure in your area, sometimes this can be as much as 2º F. To get the most accurate temps. for your mash, it would be a good idea to calibrate your thermometer about 30 min to 1 hr before your start your mashing.

Blindguardian said:

Hello everyone,
With all this talk about calibration of thermometers I went out and found a few tools that might be helpful to everyone:
Current barometric-pressure map
and this
Calculator
be mind full you will need to know your current elevation to get accurate results at the time of calibration.
Also note that the boiling point of water changes almost daily/hourly due to the current barometric pressure in your area, sometimes this can be as much as 2º F. To get the most accurate temps. for your mash, it would be a good idea to calibrate your thermometer about 30 min to 1 hr before your start your mashing.

Click to expand...

Good point!

The adage that water boils at 212*F at sea level and can simply be adjusted for altitude does not take into account that:

The 212*F boiling point at sea level also includes standard atmospheric pressure of 29.92 inHG

That's why I just got a $6 lab thermometer and calibrate the thermometer I'm using in the MLT for mashing temps or the thermometer in the HLT for strike water temp.