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General Category => Yeast and Fermentation => Topic started by: Herminator on October 23, 2013, 09:52:06 PM

Title: Fermentation Temp Measurement
Post by: Herminator on October 23, 2013, 09:52:06 PM
I recently brewed up a belgian dubbel and pitched Wyeast 1214.  Fermentation took off in about 12 hours and has been rather active.  Smells like someone is baking banana bread in the fermentation chamber.  Anyways...I have the chamber at 72 ambient temp, but am a little concerned about fermenting too high with fermentation action inside.  Based on what I have read, that could reach 10 degrees higher....which would put me at much higher than suggested temps.

So, my question.  What do people do to measure the actual temp. of the wort? So, what are other people doing besides just a temp sticker on the side?  Anyone have good luck with thermowell?

Thanks. 
Title: Re: Fermentation Temp Measurement
Post by: morticaixavier on October 23, 2013, 10:10:07 PM
thermowells are great but I have always been happy with the stick on fermentometer. I will say that 72 ambient is a bit too high already. I like to keep my ferm chamber around 64 for the beginning of most, if not all ale ferments. Some, like kolsch I will actually go lower.

With Belgians, big beers, and saisons I will bump the temp up to 74 after the first 3-4 days and turn off the temp control (or turn on heat) at the very end aiming for 78ish. some saison strains obviously like it a lot warmer but I often get a fusel headache when I drink homebrewed saison and I suspect the 'wisdom' of the high ferment temp.
Title: Re: Fermentation Temp Measurement
Post by: Herminator on October 23, 2013, 10:21:13 PM
Thanks for the suggestion.  I know that wyeast suggests 68 degrees at the lowest for this strain and thought I was doing alright with keeping it at middle range (68-75), but then became concerned about the active fermentation temp inside.  Hopefully I haven't pushed this too high (80) active fermentation temp. I think i may just have to tape my probe to the side and see what it says. 

Thanks. 
Title: Re: Fermentation Temp Measurement
Post by: morticaixavier on October 23, 2013, 10:24:19 PM
Thanks for the suggestion.  I know that wyeast suggests 68 degrees at the lowest for this strain and thought I was doing alright with keeping it at middle range (68-75), but then became concerned about the active fermentation temp inside.  Hopefully I haven't pushed this too high (80) active fermentation temp. I think i may just have to tape my probe to the side and see what it says. 

Thanks.

take those suggestions from the lab with a grain of salt. especially the low end. but even if you want to keep it in the suggested range, aim for the low end.
Title: Re: Fermentation Temp Measurement
Post by: HoosierBrew on October 23, 2013, 10:45:58 PM
Thanks for the suggestion.  I know that wyeast suggests 68 degrees at the lowest for this strain and thought I was doing alright with keeping it at middle range (68-75), but then became concerned about the active fermentation temp inside.  Hopefully I haven't pushed this too high (80) active fermentation temp. I think i may just have to tape my probe to the side and see what it says. 

Thanks.

take those suggestions from the lab with a grain of salt. especially the low end. but even if you want to keep it in the suggested range, aim for the low end.
For sure.  I've used 1214 many times and I think that pitching at ~ 64F , holding for 2-3 days, then slowly ramping up until completion gives by far the best results. That comes after fermenting it too warm a time or two and getting giant banana bombs. +1 to taking the fermentation temp ranges (low end especially) with a big grain of salt.
Title: Re: Fermentation Temp Measurement
Post by: Joe Sr. on October 24, 2013, 02:01:04 PM
As far as temp measurement, the stick on thermometers are pretty accurate.

No need to over think it.

FWIW, if you ferment too high and get fusels it is possible that they may age out.  If you have the space and can store the beer it would be worth it.

I've had a couple batches in recent years hit the mid to upper 70s on fermentation temps  and did not experience any excessive fusel production.  It is/can be very yeast dependent.
Title: Re: Fermentation Temp Measurement
Post by: corkybstewart on October 24, 2013, 02:47:40 PM
I use a thermowell in my conical and love it.  I will say that the stick on thermometer usually is about 4 degrees higher than what the digital readout on my temp controller says.  Maybe I'm wrong but I trust the digital more than the $2.00 stick-on.  The thermowell and temp controller are much more precise than me constantly having to read the thermometer and adjust ambient temp as fermentation activity peaks and then subsides.  Set it and forget it!!!
BTW I made my thermowell from the diptube of an old rusted out keg that someone gave me so it was essentially free.  I just folded the bottom end over a couple of times and beat it with a hammer so that it's completely watertight.
Title: Re: Fermentation Temp Measurement
Post by: a10t2 on October 24, 2013, 03:14:05 PM
I will say that the stick on thermometer usually is about 4 degrees higher than what the digital readout on my temp controller says.  Maybe I'm wrong but I trust the digital more than the $2.00 stick-on.

I'm the opposite... There's much more that can go wrong with a digital thermometer.

Either way, I think you need to calibrate them both.
Title: Re: Fermentation Temp Measurement
Post by: denny on October 24, 2013, 03:22:44 PM
Thanks for the suggestion.  I know that wyeast suggests 68 degrees at the lowest for this strain and thought I was doing alright with keeping it at middle range (68-75), but then became concerned about the active fermentation temp inside.  Hopefully I haven't pushed this too high (80) active fermentation temp. I think i may just have to tape my probe to the side and see what it says. 

Thanks.

Forget what they recommend and trust your senses and experience.  I've found that if I run that yeast above 65F, I get so much bubblegum and banana from it that I can hardly drink the beer.  Your tastes may be different, but trust yourself, not what the yeast companies say.
Title: Re: Fermentation Temp Measurement
Post by: hubie on October 24, 2013, 06:04:07 PM
Based on what I have read, that could reach 10 degrees higher....which would put me at much higher than suggested temps.

I keep hearing that 10 degrees, and sometimes it is 5 degrees, but it always anecdotal.  I suppose at some point I will set up my own experiment, but with all the agitation going on in the fermentor from thermal gradients and CO2 production, during active fermentation I can't see how there is going to be significant differences in temperatures anywhere in the beer.  The difference in temperature between a thermowell and something on the outside of the fermentor will strongly depend upon the type of device and how it is mounted.  A hard cylindrical temperature probe (like from a Ranco controller) makes horrible physical contact (almost no surface area contact) with the cylindrical wall of the fermentor, so it is important to cover them well with an insulator (bubble wrap) and lots of tape because the probe will measure the temperature of the air around it better than it will measure the temperature of the fermentor.  A stick-on thermometer makes great contact with the fermentor via its adhesive, but you're relying on something that has one side exposed to the air and the other side that has a thermal insulator (glass/plastic) between it and a large thermal mass (beer).

As Sean says, if you really want to know, you need to calibrate them, but make sure you calibrate them like you will use them because you might find the stick-on ones have one offset when on a glass carboy, and another when on a plastic carboy or bucket.  The good thing about all of this is that if you set everything up the same, you'll get consistent results.  You need to keep in mind that if someone says they get great results fermenting at 64F, not knowing how they are measuring temperature and what their offsets are, that might not be the same 64F to you. (Yeah, I know, I hate those "it is different from system to system" answers too...)
Title: Re: Fermentation Temp Measurement
Post by: morticaixavier on October 24, 2013, 06:28:52 PM
Based on what I have read, that could reach 10 degrees higher....which would put me at much higher than suggested temps.
[...]
I keep hearing that 10 degrees, and sometimes it is 5 degrees, but it always anecdotal.  I suppose at some point I will set up my own experiment, but with all the agitation going on in the fermentor from thermal gradients and CO2 production, during active fermentation I can't see how there is going to be significant differences in temperatures anywhere in the beer.  [...]

I think the 10 degree variance in questions is the one between the beer (as you say, anywhere in the beer) and the ambient temperature of the fermentation chamber.

Other than that +1 to your points.
Title: Re: Fermentation Temp Measurement
Post by: Herminator on October 24, 2013, 08:22:23 PM
All really great feedback.  Thanks everyone.  This is my first attempt at a Belgian and knew I could maintain the higher temps...but then spaced on the fermentation temp increase.  This might end up being a brew that would have better inside where it is a little cooler.

Either way, I have learned a lot with this brewing and fermentation process.  While I am a fan of bananas...not sure if I want a bottle of them.  Oh well, only time will tell. 

Thanks again everyone.  I will have to figure some stuff out in my fermentation chamber. 

Title: Re: Fermentation Temp Measurement
Post by: Jimmy K on October 24, 2013, 08:33:34 PM
My thermometer has a probe and an infrared reader. IR is more of a toy than truely useful in brewing, but it does read the temperature of beer through a glass carboy pretty well. I've been using it for that a lot.
Title: Re: Fermentation Temp Measurement
Post by: klickitat jim on October 24, 2013, 09:06:07 PM
Another way is to figure out what ambient temps work for you and stick with them. I know that I've been slowly lowering my chamber temps to hit what I like. Currently I brew with 1056 at 62° ambient. Probably about 65 ish actual
Title: Re: Fermentation Temp Measurement
Post by: a10t2 on October 24, 2013, 09:55:03 PM
I keep hearing that 10 degrees, and sometimes it is 5 degrees, but it always anecdotal.

If you do the stoichiometry for how much energy is released during fermentation, transferred over the surface area of a 5 gal bucket or carboy in air, it works out to a 3-6°F average differential over 72 hours of fermentation, depending on fermenter material, humidity, airflow, etc. 5-10°F at high krausen seems totally reasonable to me.
Title: Re: Fermentation Temp Measurement
Post by: cornershot on October 25, 2013, 12:00:40 AM
 I have a Johnson digital controller on my fermentation fridge. I tape the probe to the side of the carboy or bucket and insulate it with a handful of fiberglass insulation in a zipper bag. The controller always reads the exact same temperature as the stick-on fermometer.
Title: Re: Fermentation Temp Measurement
Post by: tschmidlin on October 25, 2013, 06:10:27 AM
I keep hearing that 10 degrees, and sometimes it is 5 degrees, but it always anecdotal.

If you do the stoichiometry for how much energy is released during fermentation, transferred over the surface area of a 5 gal bucket or carboy in air, it works out to a 3-6°F average differential over 72 hours of fermentation, depending on fermenter material, humidity, airflow, etc. 5-10°F at high krausen seems totally reasonable to me.
The other thing to keep in mind is that the warmer it is the faster it ferments, so the more it warms up.  So if ambient is 65 the beer could be 68, but if ambient is 75 the beer could be 85.  It will depend on all of the things above, including the yeast strain.
Title: Re: Fermentation Temp Measurement
Post by: Herminator on October 25, 2013, 12:28:18 PM
All really great feedback.  Learned a lot with this batch.  I turned off the heater and the chamber has dropped down to a 65 ambient temp.  Obviously missed the crucial time, but live and learn.  Thanks again for all the feedback and suggestions.  Time to switch up some things. 
Title: Re: Fermentation Temp Measurement
Post by: hopfenundmalz on October 25, 2013, 01:51:21 PM
Based on what I have read, that could reach 10 degrees higher....which would put me at much higher than suggested temps.

I keep hearing that 10 degrees, and sometimes it is 5 degrees, but it always anecdotal.  I suppose at some point I will set up my own experiment, but with all the agitation going on in the fermentor from thermal gradients and CO2 production, during active fermentation I can't see how there is going to be significant differences in temperatures anywhere in the beer.  The difference in temperature between a thermowell and something on the outside of the fermentor will strongly depend upon the type of device and how it is mounted.  A hard cylindrical temperature probe (like from a Ranco controller) makes horrible physical contact (almost no surface area contact) with the cylindrical wall of the fermentor, so it is important to cover them well with an insulator (bubble wrap) and lots of tape because the probe will measure the temperature of the air around it better than it will measure the temperature of the fermentor.  A stick-on thermometer makes great contact with the fermentor via its adhesive, but you're relying on something that has one side exposed to the air and the other side that has a thermal insulator (glass/plastic) between it and a large thermal mass (beer).

As Sean says, if you really want to know, you need to calibrate them, but make sure you calibrate them like you will use them because you might find the stick-on ones have one offset when on a glass carboy, and another when on a plastic carboy or bucket.  The good thing about all of this is that if you set everything up the same, you'll get consistent results.  You need to keep in mind that if someone says they get great results fermenting at 64F, not knowing how they are measuring temperature and what their offsets are, that might not be the same 64F to you. (Yeah, I know, I hate those "it is different from system to system" answers too...)

At the 2011 NHC, Terence Sullivan of Sierra Nevada said that they had a multiple probe sensor made and put in an 800 barrel fermenter. They found an 8 degree difference in temperature. Big fermenter, but there you go.
Title: Re: Fermentation Temp Measurement
Post by: Herminator on October 26, 2013, 02:49:06 PM
Found an interesting estimate graph at the following link.  They estimate fermentation temp rises based on OG/SG.  Kind of interesting. 

http://homebrew.stackexchange.com/questions/5563/can-we-estimate-the-temperature-rise-in-the-primary-due-to-fermentation/5564#5564 (http://homebrew.stackexchange.com/questions/5563/can-we-estimate-the-temperature-rise-in-the-primary-due-to-fermentation/5564#5564)

Title: Re: Fermentation Temp Measurement
Post by: klickitat jim on October 26, 2013, 04:21:05 PM
That makes some sense to my pea brain. And it works with my thought of adjusting ambient temps. Instead of just lowering my ambient temp hit and miss, I think I'll drop it 1°f for every 10pts OG. Then raise it to the target temp after krausen drops, or roughly a week into fermentation. So if I want my 1.050 beer to ferment at 65°, I'd start it at 60 and after a week gradually walk it up to 65. I buy the earlier argument too that the internal temp rise is related to how high the ambient temp is. IE a 70° ambient would raise more than a 60°. But for low tech guys like me, I think dropping ambient 1° per 10pts wouldn't' hurt.
Title: Re: Fermentation Temp Measurement
Post by: repo on October 26, 2013, 05:01:03 PM
Jim, if I ferment a beer at 65, it will start at an ambient of 67ish, and then after fermentation begins,  I will slowly drop the ambient down to keep the beer at 65. After it is pretty much done I will raise the beer to 68-with an ambient of 70ish. My goal is to keep the beer at an actual temperature, not allow it to vary over time.  In your example the beer would start at 58ish and then if it took off climb into the 60s somewhere. But you would be fermenting it over several degrees as opposed to 65.
Title: Re: Fermentation Temp Measurement
Post by: klickitat jim on October 26, 2013, 05:10:07 PM
Now I'm confused. I thought internal temp would be higher than ambient.
Title: Re: Fermentation Temp Measurement
Post by: repo on October 26, 2013, 05:45:34 PM
It will during active fermentation, and only for a few days usually.  As fermentation slows you will need to raise that ambient back up or the beer temp will drop. The yeast experts say the first 2-3 days is where temp control is most important.
The goal is to keep the beer at a desired temperature during peak fermentation.
Title: Re: Fermentation Temp Measurement
Post by: klickitat jim on October 26, 2013, 07:15:39 PM
Ok, maybe what I wrote was confusing. When I saw you say my beer would go down to 58° I was wondering how it would go below my ambient temp.

Title: Re: Fermentation Temp Measurement
Post by: phunhog on October 26, 2013, 08:01:14 PM
So kind of a related question....where do breweries measure their fermentation temp? I assume they use some sort of thermowell...but where do they place it?  Since heat rises wouldn't the upper half of the fermenter be warmer than the bottom half?  I also know that they are all glycol jacketed fermenters. So wouldn't the beer that is nearest the cooling jacket be dramatically cooler than say the beer in the middle of the fermenter?  Or is the mixing action of fermentation enough to overcome any heat stratification? What about when fermentation is winding down?    Is that enough questions? ;)
Title: Re: Fermentation Temp Measurement
Post by: a10t2 on October 26, 2013, 08:17:20 PM
Found an interesting estimate graph at the following link.  They estimate fermentation temp rises based on OG/SG.  Kind of interesting.

Interesting, but incorrect. He both misplaced a decimal (the graph should run from ~0-60°C), and totally neglected heat loss to the fluid around the fermenter.

Here's a copy-paste from an NB topic about four years back:

Quote
I went ahead and did the math. Fermentation of glucose (I couldn't find the free energy for any disaccharides) releases 235 kJ/mol. Assuming a 20 L batch and 10% drop in sugar (about average, I think, for a 1.060 beer) that's about 2600 kJ total. Without any heat being removed, that would raise the temperature of the 20 L of water by 31°C.

You can try to estimate how much of that heat will get removed by the air, but there are a lot of assumptions involved. Assuming the heat gets released at a constant rate over 72 hours, that's a steady state release of 14 W. Just eyeballing, a bucket has a surface area of about 0.55 m^2. I'm just going to use Newton's law of cooling for simplicity, with a coefficient of 10 W/m^2-K; that could be off by as much as half. Anyway, it works out to a differential of 2.5°C, about 4.5°F.
Title: Re: Fermentation Temp Measurement
Post by: a10t2 on October 26, 2013, 08:20:42 PM
So kind of a related question....where do breweries measure their fermentation temp? I assume they use some sort of thermowell...but where do they place it?

Most tanks I've worked with have the thermowell set up on a TC about halfway up the height of the tank, and maybe 8-12" long to get it away from the jacket.

http://www.glaciertanks.com/Thermometer_Thermowell-Thermowell_9_x_1_2_NPT_Female_SS304.html