Thermometer Hell

[iXanadu]

I'm in thermometer hell. I have two digital thermometers, neither agree on the temperature of my MLT water. Neither allow me to calibrate but oddly enough the both registered 32º in an ice slushy. When reading 180ish water they are off 5-6 degrees. When checking water bath surrounding primary fermenter they are off 2º.

I use these when I monitor my mash using this Cooler Thermometer Bulkhead bulkhead gadget so I would really like to know that the *REAL* temperature is.

Can any one recommend a digital thermometer that can be calibrated and will work in my bulkhead port?

 

[nebben]

I was in the same spot at you when I bought three thermometers and expected all to agree with each other.

Sure, two of them can be calibrated, but high temps would lead to fishy results. My glass "lab" thermometer registered a few degrees different than the Miljoco, which was different than the $9.00 dial thermometer. I eventually found a boiling water temperature calculator online, and plugged in my elevation+current relative air pressure to see what H20 should be boiling at. I got a nice pot of boiling water and saw that the so-called lab grade thermometer was showing 3-4 degrees hotter in the boiling water than should be theoretically possible while the other two were much closer to the alleged maximum boiling temp for my area.

YMMV.

 

[Scut_Monkey]

I know quite a few people around here use the thermapen. It's like $60-90 but takes 3 second readings and is very accurate. The cost inhibits me but I'm kind of in the same position as you. I recently found out the thermometer I was using in my mash tun was reading 5 degrees hoter than it should so I was mashing 5 degrees cooler than I needed for about 6 batches of beer. I found two lab thermometers (digital) and did a little comparison of all the thermometer I had which totalled 6 of them. I compared them all and determined that the lab thermometers would be my new mash tun thermometers. Good luck in your search..... quite a few people go on the same search.

 

[jldc]

+1 Thermapen. I actually have two of their thermometers and they always agree within 1 degree.

 

[Zen_Brew]

I got a nice pot of boiling water and saw that the so-called lab grade thermometer was showing 3-4 degrees hotter in the boiling water than should be theoretically possible while the other two were much closer to the alleged maximum boiling temp for my area.

YMMV.

Careful with lab grade glass thermometers. Many of them are designed to only read accurately at a specific level of immersion in the fluid. Others need to be fully immersed. Even If you had a partial immersion and had it immersed to the correct level it is possible that the air immediately above the boiling water threw the reading off as the air would have been quite a bit above ambient temperature due to the presence of steam which is actually hotter than the boiling water.

 

[Zen_Brew]

There are several really good threads on thermometers you might try a read through. Here is one.
https://www.homebrewtalk.com/f11/what-thermometer-should-i-buy-127318/

The Thermapen is always highly recommended. If you have the cash go for it. You'll also find there are plenty of opinions out there. I am currently using this thermometer from Taylor which I have verified the acuracy on to within 0.1 degree F. You can find it on the bay sometimes a bit cheaper.
Amazon.com: Taylor Connoisseur Digital Folding Probe Thermometer: Kitchen & Dining

 

[boredatwork]

I have also seen the thermocouples on thermoworks.com recommended. I have one on order. They are a bit pricey, but can be cheaper than the thermopen and more versatile since there are so many types of thermocouples.

 

[rico567]

There are several really good threads on thermometers you might try a read through. Here is one.
https://www.homebrewtalk.com/f11/what-thermometer-should-i-buy-127318/

The Thermapen is always highly recommended. If you have the cash go for it. You'll also find there are plenty of opinions out there. I am currently using this thermometer from Taylor which I have verified the acuracy on to within 0.1 degree F. You can find it on the bay sometimes a bit cheaper.
Amazon.com: Taylor Connoisseur Digital Folding Probe Thermometer: Kitchen & Dining

+++1 on the Thermapen. I read lots of threads, and it's the product that came through as a consistent winner. It is not cheap, but that's not the point here. It does the job, delivers accurate temperatures with super speed. I bought the new "splash-proof" model, for $104 delivered. It folds up and follows me around in my pocket (a great feature, the way I brew), and I couldn't be more satisfied.

 

[magnj]

I'm not sure what to do either, I like the new Thermapen on paper but that forces me to use it by opening the mash tun where as the thermocouple could be used by switching out probes that could be permanently installed in different places...

 

[c0bra]

Just fyi, Thermoworks has the old model thermapen on closeout for $74 (that's vs. $96 for the new splash-proof one).

 

[Scut_Monkey]

Just fyi, Thermoworks has the old model thermapen on closeout for $74 (that's vs. $96 for the new splash-proof one).

If someone was into this a group buy could be done as you can buy 6 of them at a time at approximately ~$80 each for the new and improved splash proof model. Rather than paying $96.

 

[Evan!]

Here you go.

This is the post you're looking for in that thread.

The thermapen is nice, but if you get the thermocouple indicator like mine, you can swap probes easily. I bought that 39" wire probe and use that to continually monitor my mash. For another $30 or so, you can get the attachment that is the very same probe that the thermapen uses...so essentially you get the same thing as the thermapen, but can swap probes. I know the thermapen gets a lot of love around here, but I really like the thermocouple indicator because of all the different probes you can buy for it. I'm looking into getting one for my smoker, too.

 

[Scut_Monkey]

Here you go.

This is the post you're looking for in that thread.

The thermapen is nice, but if you get the thermocouple indicator like mine, you can swap probes easily. I bought that 39" wire probe and use that to continually monitor my mash. For another $30 or so, you can get the attachment that is the very same probe that the thermapen uses...so essentially you get the same thing as the thermapen, but can swap probes. I know the thermapen gets a lot of love around here, but I really like the thermocouple indicator because of all the different probes you can buy for it. I'm looking into getting one for my smoker, too.

Do you happen to know which thermocouple the thermapen uses. I looked at them all last night but could not figure out if they offered it and I started to get frustrated and confused. Thanks for the links above. I thought havinga swapable probe would be a good idea when I have a larger brew system.

 

[Zen_Brew]

Do you happen to know which thermocouple the thermapen uses. I looked at them all last night but could not figure out if they offered it and I started to get frustrated and confused. Thanks for the links above. I thought havinga swapable probe would be a good idea when I have a larger brew system.

I can not say absolutely having never been inside of one, but I am pretty certain based on it's accuracy and response time that the Thermapen uses a thermistor sensor, not a thermocouple sensor.

The difference is the accuracy. Thermistors are typically spec'd to be accurate within a couple tenths of a degree. Thermocouples are generally about that accurate at the lower temperatures where brewers use them, however their spec'd error is allows for about 2-4 degrees F.
http://www.omega.com/techref/colorcodes.html

I work in calibration and have never seen one out that far that is not damaged, but it is allowable per specifications due to the wide temperature range of usage, and allowable impurities in the thermocouple junction.

I'm not trying to discourage thermocouple useage, they are in fact very versatile for the reasons Evan mentioned, and I have a Cole Parmer Digi-Sense type J thermocouple meter among my temp meters that reads to within a couple tenths across the brewing temperature range. I did set the cal factors to get it this close though.

 

[Evan!]

Do you happen to know which thermocouple the thermapen uses. I looked at them all last night but could not figure out if they offered it and I started to get frustrated and confused. Thanks for the links above. I thought havinga swapable probe would be a good idea when I have a larger brew system.

Indeed...

Click here. It's model #113-159, Plug-Mounted Fast Response Penetration Probe:

This plug mounted fast response probe is designed for measuring temperature very quickly. This is the same probe as we use on the Super-Fast Thermapen and Fast Response Penetration Probe. Max temp: 482°F (250°C).

 

[boredatwork]

Just because thermistor sensor has a tighter tolerance that doesn't mean that the thermometer does.

The thermocouples from thermoworks are rated at 1-2degreeF. I think that is as accurate as you can expect without spending a lot more money. And if you want to spend more, you can get a thermocouple down to 0.1degC (within certain ranges).

Either way it certainly beats the accuracy you are get from a $10 meat thermometer. Mine tells me that water boils at 190F.

 

[Zen_Brew]

Indeed...

Click here. It's model #113-159, Plug-Mounted Fast Response Penetration Probe:

Nice link Evan. I really figured the Thermapen was using a thermistor due to the limited range and higher accuracy. Now having read your link it appears they are using special limit of error type K, and they must be pre-qualifying them to beat the traditional spec of a special type K. Also not allowing use over the entire range probably helps keep the tolerance tighter as well because thermocouples used at very high temperature seem to develope more error than ones not used that high.

 

[stephelton]

Good info here. I've been in need of a thermometer that doesn't suck. I've gone through a couple digital thermometers because the probe gets submerged in my mash. How well do the thermopens hold up (both the "splash resistant" one and the original)?

On another note, I've been using dallas 1 wire thermometers. These claim to be accurate within +/- 0.5 degrees. Though it would be a bit of work, you could build a thermometer with these. I've got quite a few, I should see how they compare to each other.

 

[springer]

I have been using the the Thermopen for a few months now its holding up well. I have the original while not splashproof there have been no problems . I also have a Cole Palmer thermocouple that has a 3 ft cord with a PVC coated probe. It works well also but I use the thermopen most all the time as I don't feel the need to keep taps on the Mash temp . The igloo loses at most 1° over an hour. I stir the crap out of the mash let it sit 3-5 minutes and check in several spots if the temps are where I want them I just close it up .

I do have the Tel-Tue dial thermo that I am planning on installing in my MLT just my lazy ass never gets around to it

I like it because the dial is huge I can actually see the #'s and its dead on with the other 2 digital thermo's

 

[iXanadu]

Indeed...

Click here. It's model #113-159, Plug-Mounted Fast Response Penetration Probe:

K, Based on all the feedback, I'm leaning towards the ThermoWorks – MTC Mini Handheld Thermocouple and a couple probes. I'm having a difficult time understanding if the 113-159 will fit in my MLT bulkhead fitting. It works with 1/8" thermometers - can you check yours and tell me what the diameter of the probe is? The 113-225 (ThermoWorks – Thermocouple Immersion, General Purpose, and Air Probes.) looks like it will fit my MLT fine. (I'm thinking .12" is 1/8 if I'm doing the math right).

 

[BOBTHEukBREWER]

If you have a friend who works in a hospital laboratory you can get yours calibrated (on the quiet, of course) against a thermometer that is itself calbrated to national standards. My digital thermometer reads 67 deg c when the true temperature is 66 deg c .

 

[Evan!]

K, Based on all the feedback, I'm leaning towards the ThermoWorks – MTC Mini Handheld Thermocouple and a couple probes. I'm having a difficult time understanding if the 113-159 will fit in my MLT bulkhead fitting. It works with 1/8" thermometers - can you check yours and tell me what the diameter of the probe is? The 113-225 (ThermoWorks – Thermocouple Immersion, General Purpose, and Air Probes.) looks like it will fit my MLT fine. (I'm thinking .12" is 1/8 if I'm doing the math right).

Yes, .125" is 1/8". I don't yet have my 113-159. It's in the mail. If you can wait, I'll have it in a few days and measure then. But the 113-225 looks like it'd work well for your purposes. I don't have a bulkhead, so I just drilled a little hole in my MLT lid and then I feed the 113-372-T through that. I ordered the 159 because I want to be able to use it with cooking/grilling as well.

 

[iXanadu]

Yes, .125" is 1/8". I don't yet have my 113-159. It's in the mail. If you can wait, I'll have it in a few days and measure then. But the 113-225 looks like it'd work well for your purposes. I don't have a bulkhead, so I just drilled a little hole in my MLT lid and then I feed the 113-372-T through that. I ordered the 159 because I want to be able to use it with cooking/grilling as well.

Did you get the probe? If so, what is the diameter?

 

[magnj]

I ordered an MTC with 113-159 earlier this week, hoping it comes for the weekend and that it is more accurate than my dial meat thermometer.

 

[Evan!]

Did you get the probe? If so, what is the diameter?

Got it. It rocks faces.

The first 3/4" up from the tip of the probe is about 1/16", then it transitions to 1/8" caliper after that.

 

[shek]

david_42 had a good idea here
He says that if you boil vodka it will stay at 172 deg F until all of the alcohol is gone. I tihnk this could give a pretty good calibration point around mash temps.

 

[Saccharomyces]

ThermoWorks makes some great stuff. I won't buy a thermometer from anybody else.

 

[Zen_Brew]

david_42 had a good idea here
He says that if you boil vodka it will stay at 172 deg F until all of the alcohol is gone. I tihnk this could give a pretty good calibration point around mash temps.

This is a fascinating concept, but in reality I'm not sure it would provide a stable reference point. While Ethanol does in fact have a fixed boiling point, I believe that as it becomes diluted with water the boiling point rises. As you heat a vodka the alcohol will boil out of the mixture well before the water which is further dilluting the percentage of alcohol in the mixture, and I would think it is therefore changing the boiling point as it heats. I know the freezing point of liquor changes by a pretty big amount depending on the alcohol content. That is why you can stick a 100 proof liquor in your freezer and have it not freeze, but put a 40 proof one in there and end up with it freezing.

 

[shek]

This is a fascinating concept, but in reality I'm not sure it would provide a stable reference point. While Ethanol does in fact have a fixed boiling point, I believe that as it becomes diluted with water the boiling point rises. As you heat a vodka the alcohol will boil out of the mixture well before the water which is further dilluting the percentage of alcohol in the mixture, and I would think it is therefore changing the boiling point as it heats. I know the freezing point of liquor changes by a pretty big amount depending on the alcohol content. That is why you can stick a 100 proof liquor in your freezer and have it not freeze, but put a 40 proof one in there and end up with it freezing.

Boiling and freezing are very different though. I'll give this a whirl and report back. Maybe even try it with some 153 or 190. I've got a couple different thermometers and I'll take readings from all three until there is significant boil off. I'm guessing that it will stay at a plateau around 172 degrees for several minutes and then once the ethanol is gone the temp will rise to 212. If 172 truly is the boiling point for 40% (80 proof), for at least the first couple moments of boiling then I don't think there's much change in the boiling temperature until most of the ethanol is gone (<5-10%), the BP of pure ethanol is also 172.

 

[Zen_Brew]

Cool I'd be interested in the results. Make sure to use cheap Vodka, no sense boiling all the alcohol out of Grey Goose, Kettle One, or Chopin.

 

[Saccharomyces]

As long as it isn't under pressure it will boil at the BP of ethanol until most of it is gone, then the boil will slow and the temperature will rise.

I would avoid using over 100 proof for this because of the risk of fire.

 

[shek]

As long as it isn't under pressure it will boil at the BP of ethanol until most of it is gone, then the boil will slow and the temperature will rise.

I would avoid using over 100 proof for this because of the risk of fire.

That thought occured to me. I have a double boiler though. Although I think I'll just go the cheap vodka route. I'm at a whopping 43 ft above sea level too, so that shouldn't affect my readings. Will post results later (maybe tonight).

 

[iXanadu]

Got it. It rocks faces.

The first 3/4" up from the tip of the probe is about 1/16", then it transitions to 1/8" caliper after that.

Thanks for the reply Evan. I'll order it this week-end, be here in time for my next brew in 2 weeks!

Cheers