Thermometer for AG = lots of (easy) questions - feedback needed

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julian81

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I've been reading through the forums for hours and hours, maybe days combined and I have a ton of questions that I just can't seem to find the answer for...or if I do I keep going in circles. Really hope you guys can steer me in the right direction.

Basically, I want accurate/temp and hydrometer readings. Here's my dilemma. My glass 12"+ cheapo thermometer seems to be off. I froze distilled water and then put the broken up chunks in a glass of distilled water and waited for it to equalize before taking a temp reading, and it came in at 36-37F, so I'm gonna round up and say about 5F off. I hate having inaccurate equipment and having to factor this into my calculations, especially since I'm a newbie.

I'll be brewing my first AG batch this coming weekend and I'd like to have accurate temp readings while mashing and fermenting and well to gauge the HLT water too. I've heard of people using cheapo temp sensors from Walmart, Target, etc or even using those nifty Thermapens. So many questions though...how do you measure the fermentation temp with a thermapen?

I read another thread suggesting to get a K type thermocouple, which I think I like the idea of better than a thermapen, since I can attach various K type probes. This seems easier for taking fermentation temp, since I can just dangle a probe through the carboy cap for quick easy temp readings. This could be used just as easily for taking water and mash temps.

I was looking at the following options: http://thermoworks.com/products/handheld/index.html

What would you guys recommend?

What kind of K probes would you recommend for reading strike water temp, mash temp and fermentation temp?

Another option, that I kind of like is wireless thermometers like this:

http://www.oregonscientificstore.com/oregon_scientific/product.asp?itmky=70477

I could use this for monitoring fermentation temps by dangling the probe into the carboy and leaving it there to monitor the temp while in another room.

I'm really looking for something accurate, priced right (I don't mind paying more for features that simplify my life) and versatile for brewing.

(additionally, my hydrometer is off by 4 points. i.e. it reads 1.004 in distilled water @ 60F. I'm not sure this is so much of a problem since I can offset easy enough for the few times I'll need to take gravity readings, AND I just purchased a nifty refractometer off ebay from hong kong. WIN!)

Anyway, point me in the right direction guys...I am brewing this weekend for the first time and will use what I have, but would like to have some better/digital stuff on order for the next batch (cuz it won't be long till I wanna brew again..probably the week after!)

thanks!
--julian
 
You should be able to calibrate the thermometer, have you taken readings of boiling water? I usually calibrate at boiling (because its closer to mashing temp) and check accuracy with freezing.

If you are brewing your first batch AG you should be ok with a thermometer. I probably wont be working with thermocouples until I build some sort of heat exchanger where I could very accurately control my mash temp.
 
I have not yet tried the thermometer in boiling water, but if it was already off by 5F in cold water, it would probably be off by 5F in boiling water, right?

I can't see how you determined your current thermometer is 5 degrees off: since it was a mixture of warmer water plus however much ice, the only thing you can infer is that the actual temperature of the sample was above 33 degrees. Did you measure what the volume and temperature of the water was, as well as what the mass of the ice was? That would be the only info I think you'd have to go by to be able to figure out what the temperature of the sample was.

For simplicity sake, it is easier to measure the boiling point of distilled water (the only factor with that is figuring out your elevation compensation).
 
I have not yet tried the thermometer in boiling water, but if it was already off by 5F in cold water, it would probably be off by 5F in boiling water, right?

Yes,exactly!

And like Bheher said, you are more interested in the upper temp ranges. So if you determine you are 5 degrees off at boiling point, so be it. Just make note of that fact and know you are 5 degrees off and compensate. No big deal, is it ?
 
Yes,exactly!

And like Bheher said, you are more interested in the upper temp ranges. So if you determine you are 5 degrees off at boiling point, so be it. Just make note of that fact and know you are 5 degrees off and compensate. No big deal, is it ?

That makes sense. I'll definitely be testing at boiling tonight, before I drop another $100 on more equipment. Cheers!
 
Google CDN for a thermometer. Just got one from amazon and love it. Cost $14 and is very accurate. I found the best way to get a really accurate 32 degrees was to put a bunch of snow in a cup and add water. Makes a slushy. Calibrated this to 32. Also, remember to check what the temp is supposed to be for a boil at your elevation. I am in MN and water boils at 210 at 1200 ft
 
I would not assume that a thermometer that is x degrees off at boiling or freezing is also x degrees off at 150. I checked my collection before I got my thermapen and did not find the shift to be the same across the scale.
 
So...I just checked the local news station's website for elevation stats around Seattle. My neighborhood apparently has an elevation of 50-150. Pretty low...which it should be considering I can see the water from my place.

I just boiled in a stainless steel cooking pot, some distilled water. I held the thermometer in there by hand for a few minutes. It shot right up instantly, but took a bit longer to reach it's peak.

Looks like distilled water is showing 212F on my thermometer. So I would assume then that my thermometer is OK? If so, what's the deal with not seeing 32F on my ice/water test?

Another thing, holding this thermometer over the liquid/area I want to take the temperature of is annoying, and it's slow. I think for convenience and efficiency sake, I'll be investing in a quick response digital thermometer/thermocouple. I like technology.
 
A good fast thermometer comes in handy.

Ive got this one
http://www.amazon.com/gp/product/B00064BCPM/?tag=skimlinks_replacement-20

I have a PID and RTD sensor in my boil keg and will be adding others where they will come in handy but for the last year I have used this pen to get accurate, quick readings down to the decimal point. It is one of my most used tools on brew day.
 
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Photopilot:

Have you had any issues with this? Does this just sit on the top of your mash? Or is it so quick you can just hold it for a few seconds? Same with the water in the HLT? Do you use this to check the temp of your fermenter? it doesn't look long enough to fit down a carboy neck...
 
Thermoworks Thermapen. That's all I have to say.


But let me add more: I love mine, seemingly the best single piece of equipment I have by far. As for how to use it, swing the probe out, put in mash, or wort, or water bath, or whatever you want to measure (like beef on the barbie), wait about 3 to 4 seconds while it quickly arrives at a temp in tenths of degrees... and you get a certificate that says it's uberaccurate. Without a doubt it's worth it considering that temp is one of the, or maybe the most, important variables in brewing.
 
Frodo, yeah I've been looking at all the Thermoworks products. A brewer friend of mine has the thermopen and swears by it, but I'm actually looking at getting something like a thermocouple with K type probes, cuz then I can pretty much customize and attach any type/size/length of probe, including the one the thermopen uses. I could use the thermopen straight K type probe for mash/water temps, and then get a longer one for inserting into the carboy for fermentation temps.

Any thoughts on this? I posted a few links to possible products a few posts back.

--Julian
 
I don't know anything about the k type probes, including cost... the temps I'm most concerned with are mash temp and fermentation temp. I use a cooler for mashing and every 15 minute or so I open up the cooler, stir the mash (especially using an "up" motion with my huge spoon) while having the thermapen inserted in the top of the mash so the grains are sort of flowing over the probe to get a good average, and measure the pH at least the first time. With a probe and not mixing as often, I'd be worried about cold or hot spots in the cooler... On the other hand, if you're recirculating with a pump in a converted keg that may be a different story? Maybe not I dunno.

As far as fermentation temps I find the Fermometer strips to be good, I've had many and they all seem to be reading the same (and have ruined a few by getting too much water on them - I finally learned to not attach them permanently to the carboy but instead use tape so they can be pulled off for cleaning). Anyway, those strips seem to be good at measuring the temp INSIDE the fermenter without 1) causing a possible infection by pulling off the airlock/bung to stick some probe down into the wort, and 2) disturbing the CO2 layer. Once I put the bung on the carboy and the airlock on, it's there to stay for at least 3 weeks, unless I have to replace the airlock with a blowoff tube in the rare instance for a couple days during a particularly vigorous fermentation in a 6.5 gal carboy.

I really didn't check out your links though... I just wanted to say how much I like my Thermapen! I can even walk around the house and find the "hot" and "cold" spots it's so sensitive.
 
+1 for the thermapen. I got sick of soaking Target brand digital thermometers and bought one.

Assuming that a 5deg difference @ freezing equals a 5deg difference @ boiling is not generally valid. This implies that the thermometer response is linear, which is not the case over such a large temperature range. Electronic thermometers can be more linear than glass, but you're still going to have a larger variation at higher temperature.

If you wanted to be superanal, you could calibrate the thermometer across multiple known temps from freezing to boiling and construct a calibration curve. I don't think this is necessary for any homebrewing application though. Just measure the difference at boiling and use that as a rule of thumb for mash temperatures.

Incidentally, Thermapen validates the linearity for you:

http://www.thermoworks.com/blog/2010/11/is-one-calibration-point-enough/
 
Photopilot:

Have you had any issues with this? Does this just sit on the top of your mash? Or is it so quick you can just hold it for a few seconds? Same with the water in the HLT? Do you use this to check the temp of your fermenter? it doesn't look long enough to fit down a carboy neck...

Here is how i use it.

I have an element in my HLT but no thermo-sensor. I heat most of the water in my keggle then pump it up to the HLT. I have a 3 tier. So i step up the ladder and place the thermometer in the HLT to see where my temp is. I turn on the element to bring it up to temp.

I drain the water into my MLT. Check the temp for my strike temp. I add more hot or cold water to get to my strike temp and volume. I then add grains and mash it. I stir it well and then take a temperature in a few places to see where I am at. I then shut the lid and walk away. I know from experience I won't loose more than a degree or 1.5 unless I keep peeking and taking measurements. I will use this thermometer to get my strike water up to proper temp, then again to double check my wort during cool down.

As far as fermentation I'm with Frodo, fermometer works fine. I figure the fermenting wort will be at most 4-5 degrees over room or whatever temp during the most vigorous part of the process. I've got a fermenting freezer now with a controller that I used for my last brew, but that's a story for another episode.

It usually only takes 2-3 seconds to get a reading, which it seems fairly fast unless you are perched on a sketchy ladder over 180+ degree water. The higher end ones in which you can change out the probes would be very nice in letting you add a waterproof probe and tossing it into my HLT and observing from a safer local without steaming my hand.
 
The thermapen is great, I'm sure, but I couldn't budget spending 80 bucks on a thermometer. So I got the RT600C from thermoworks, the same company.

http://www.amazon.com/gp/product/B002GE2XF8/ref=oss_product

Check it out, 42 5-star ratings. Also, it was ranked the best by some culinary magazines. It just gives readings a bit slower than the thermapen, but it's extremely accurate and only costs 25 bucks.

Every other thermometer I've looked at in the same price range had some bad reviews or problems, but not this one. Get it. Seriously.
 
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The thermometer I use and love is a type k thermocouple with a built in infrared. I bought a bunch of probes, so what I do is place and leave a probe in my boil kettle, MLT, and HLT. Then as I want to check anything, I just plug in the probe and take the reading. I also have the option of just "shooting" it with the infrared to get a ballpark. Not bad for the 45 bucks or so that I paid for it especially since the emissivity is adjustable.
 
Thanks all for your feedback, I REALLY appreciate it. Given the high praise, and popularity, I jumped on the Thermopen bandwagon. I just bought one and had it shipped 3 day. I plan on using this to measure strike water temp, sparge water temp, mash temp, and the cooled wort temp. I'm going to stick to the fermometer strips on my carboy for now to measure fermentation temps. This should do me perfectly until I can build a fermenting chamber with a dual stage temp controller (down the road).

Thanks guys!
--Julian
 
I am very happy with my CDN proaccurate thermometer. Get a very accurate reading in 5 secs. Cost $85 less too
 
Another plug for thermapen. I have used taylor and other instant type thermo's and while nice, just don't measure to the thermapen. Plus that thing is great for general kitchen use if you cook a lot.
 
Thing I don't grasp in this thread is the value placed on speed--few if any of the substances we work with in homebrewing have critical time windows affected by the temperature changes possible with the density and amounts of mass in play. The enzyme reactions don't happen so fast across the volume of mash that a correction can't be applied. Likewise alteration of a volume of water that large is slow enough that constant readings would seem more useful than spot readings. I guess the multiple probes system is the closest for that--though sticking a long cheap dial thermometer into your containers is going to be just as easy, possibly cheaper too. Easier, maybe as you can spot check knowing that what you're looking at is the result of ongoing measurement rather than waiting, even for an 'instant read' thermometer to come up.

I don't mean to sound old fashioned or too RDWHAHB about it, but at these masses (measures in quarts, tens of pounds, and gallons!) the urgency of speed in spot checking seems over rated. And expensive!
 
for fermentation temps I use my digital kitchen one that you use to temp a roast in the oven. It has a probe on the end of a wire , you lower it into the beer and just jam in the stopper with your blowoff-airlock and leave the unit outside Works great
Available at kitchen stores probably 25 bucks or less
 
I find that the temperature of my mash can vary by as much as a +-1F depending upon where I place the probe in the cooler. So it seems kind of pointless to get a thermometer more accurate than 1F since you're really only taking a localized measure anyway. You can average over multiple locations but having the cooler open during the procedure results in more heat loss, which defeats the purpose. I use a cheapo Maverick brand remote digital roasting thermometer primarily so I can monitor the temperature with the lid closed. I calibrated it against a glass lab thermometer over the entire range of 32F to 212F and it's accurate to 1F.
 
Thing I don't grasp in this thread is the value placed on speed--few if any of the substances we work with in homebrewing have critical time windows affected by the temperature changes possible with the density and amounts of mass in play.

For me it wasn't apparent how nice the speed would be until I experienced it... I got my Thermapen for accuracy, not the speed, but I've found I really appreciate the speed too.

I mash in a cooler, so each time I open the lid to check temp I lose some heat. If I can grab the temp and get the lid back on quicker I lose less heat. I can also give my mash a quick stir while the temp probe is in it (takes a little coordination) and by observing the temp swings on the Thermapen I can see that there are hotter and cooler pockets; when the Thermapen stabilizes at a certain temp 1) I know the mash is now uniform in temp, and 2) I know what that temp is and if I need to add a bit of boiling water to get it back up a couple degrees. Also quick temp readings actually save me quite a bit of time throughout a brew day if each temp reading only takes a few seconds, rather than a minute or so each time.
 
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