How to measure ACTUAL fermentation temp?

[dawalkertiger]

I’m a new brewer here. Have my first conditioning in the bottle (extract Kolsch-style that I got with my kit), and my version of the all grain BIAB Reapers Mild from azscoob in the fermenter (9 days in). I use plastic buckets to ferment in (typical 6.5 gallon size with drilled lids). Both were 5 gallon batches.

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My question is, with the weather finally starting to warm up around the country, I’ve been seeing a ton of posts on here regarding fementation temp. I understand the idea that ambient room temperature isn’t a great measure, or that ambient temp needs to be 5-10 degrees lower than what you want to be fermenting at, since the fermentation process produces its own heat. Short of opening up the bucket and sticking a (sanitized, of course) thermometer in the bucket. How can I really tell what the actual temp of my fermentation is? Do the aquarium style stickers work on a bucket, or just carboys? And does that even really measure what’s going on inside the fementation vessel?

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What I am doing now, is I have clipped my dial thermometer to the lid of the bucket. The probe goes right down beside the* bucket, probably ¼ to ½ inches away from bucket.




Am I getting a decent measurement here? When it was colder a few weeks ago, it was reading 64F pretty constantly, now it’s warmed considerably up in Missouri, so I’m getting a reading of about 68F.

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So, with my setup and the close proximity of the probe to the fermenter, am I getting the fermentation temp? Ambient room temp? Or somewhere in the middle?

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Thanks!

 

[phuff7129]

You need a Thermowell. Basically it is a bung that has a stainless steel hollow probe that goes into the fermenter. You then can slide your temperature probe into the thermowell to measure actual temp insider your fermenter. Here is an example. http://www.midwestsupplies.com/stopper-thermowell.html
This one if for a carboy but you could drill out the lid of your bucket to match the size of the bung.

 

[LLBeanJ]

+1 on the thermowell. I use one of these...

http://www.brewershardware.com/Straight-Wall-Thermowells/

 

[acidrain]

If you put the thermometer in contact with the bucket, and used some insulation over it, it would give you a better reading than the way you have it.
A thermo-well is best.

 

[dawalkertiger]

OK. 2 for thermowell. I've heard of those but not too often. Anything else? Are most people just adding a few degrees to ambient?
What about those stick on ones? Do they work?

 

[dryboroughbrewing]

I use a thermowell, however, for years I put my probe in a little insulated pocket (styrofoam) that was pressed directly to the side of my fermenter without issue. I've actually done some side by side testing and did not notice a sizable temp difference between the two methods. (I bungied the styrofoam to the outside).

 

[phuff7129]

OK. 2 for thermowell. I've heard of those but not too often. Anything else? Are most people just adding a few degrees to ambient?
What about those stick on ones? Do they work?

The stick on ones probably work better on a carboy.

Controlling fermentation temperatures is a very important component in brewing. I recently added a fermentation chamber so I can do just that and I think it has made a big impact on the quality of my beer. I have a temperature controller with it's sensor inside a thermowell in my fermenter so I am controlling my actual fermentation temperatures.

I started out fermenting in my basement which has a consistent temperature between 62 and 65 degrees. I fermented a lot of brews in that basement without any problems. I don't know what the temps inside my fermenter were but I knew they would ferment fine in those temps so I did not worry about it. I only made the switch to a fermentation chamber to take my brewing to the next level and to also be able to brew lagers and Belgians.

If you have an area where you have steady temps in the 60's you should be able to ferment most ales without any trouble. Then move up to a fermentation chamber when you can.

 

[dawalkertiger]

Yeah. The genesis of this thread is deciding to buy/build some kind of fermentation chamber now or wait.
I may look into using a swamp cooler for the time being.

 

[chungking]

Do these thermowells allow the airlock to be installed as well? Where does the airlock go if not?

 

[bacchusmj]

If you set the thermowell are you setting for the middle of the yeast temp range or a tad lower, as to allow for lag in the fridge?

For example, if you have a yeast strain with a range of 65 to 75, are you setting it at 70?

 

[i4ourgot]

I use the sticky thermometer and when I notice it starting to climb put some ice packs on the outside of my fermenter. This seems to work for me, I also leave my fermentor in the closet and the temperature doesn't change that much.

 

[phuff7129]

Yeah. The genesis of this thread is deciding to buy/build some kind of fermentation chamber now or wait.
I may look into using a swamp cooler for the time being.

Yeah I understand. I kept an eye out on Craigslist for a long time and finally found a little 5 cu. ft. chest freezer for free. It's was ugly but it worked. I cleaned it up a little and bought the STC-1000 temperature on Ebay, http://www.ebay.com/itm/110V-All-pu...798?pt=LH_DefaultDomain_0&hash=item2a275ea256
I added a small space heater and for around $40 I have a fermentation chamber.

 

[LLBeanJ]

Do these thermowells allow the airlock to be installed as well? Where does the airlock go if not?

The one I have from Brewers Hardware requires another hole if you want to use an airlock. I ferment with ale pails and slip the thermowell in the airlock hole/grommet and don't bother with an airlock. It would be a piece of cake to drill another hole in the lid and slip a standard grommet in it so that I could also have an airlock, but I wasn't concerned enough to bother with it since the fermentation takes place in a sealed ferm chamber.

I can't tell for sure, but it looks like the bung type thermowell/stopper for a carboy has a hole for an airlock.

 

[dawalkertiger]

Yeah I understand. I kept an eye out on Craigslist for a long time and finally found a little 5 cu. ft. chest freezer for free. It's was ugly but it worked.

Could you get 2 buckets in the 5 cu. ft. model?

 

[brokebucket]

Listening to the Brew Strong podcast, they recommend taping the thermocouple to the side of the fermenter and insulate it. Using this method, they claim to be within 1 degree of the temperature of the beer. I would imagine that using a thermometer in a similar manner would have the same effect.

This is what I do in my small fridge fermenting chamber and use a ferm-wrap for heat. Maintains temp +/- 1 degree.

the pic shows the setup with no insulation...fermwrap is around back, t/c taped to the side. I wrap it all up with insulation and let er rip.

 

[LLBeanJ]

If you set the thermowell are you setting for the middle of the yeast temp range or a tad lower, as to allow for lag in the fridge?

For example, if you have a yeast strain with a range of 65 to 75, are you setting it at 70?

Not necessarily. I'm setting it based on what flavors the yeast will produce at what temp. For example, I just brewed a milk stout this past Sunday using WLP001. Off hand, I'm not sure what the temp range for this strain is, but I know that it produces a clean profile at 65°, which is what I'm generally going for whenever I use it, so I set both upper and lower set points on the controller to 65°. I believe my controller is configured for a 1° differential and a 15 minute minimum cycle to prevent short-cycling of the compressor, so the beer/wort temp will fluctuate between 64 and 66.

 

[phuff7129]

If you set the thermowell are you setting for the middle of the yeast temp range or a tad lower, as to allow for lag in the fridge?

For example, if you have a yeast strain with a range of 65 to 75, are you setting it at 70?

I haven't found the lag to be more than a degree so it has not been an issue. Of course that may change depending on what I am trying to do.

I ferment most of my ales at 64 degrees so the temp may vary from 63 to 65 which is not a problem for most ale yeasts. The main reason I want a fermentation chamber is so I can ramp up temps on Belgian yeast strains. I might start a Belgian strain at 68 and then ramp it up to 78 or higher over 5 days.

 

[phuff7129]

Could you get 2 buckets in the 5 cu. ft. model?

Nope, just one bucket. The 5 cu ft model has a deep section and then a shelf. One bucket will fit on the shelf. The deep section is too small for a bucket. I could build some sort of stand to bring the deep section up to the same level as the shelf and then I could get 2 or 3 buckets in it.

 

[ScottG58]

I tried thermowell and temperature probe taped to the side of the fermenter with bubble wrap on to of it to insulate. In my unscientific study, both readings were the same.

 

[bruin_ale]

Agree with the tape it to the side folks.. I use 2 bungy cords to hold a reflectix insulation jacket around my carboy - then I stick the temp probe under the bungy so it's held tight against the carboy. I've measured versus the core temp of the fermentation and there was no difference. I'd rather not have to put a temp probe directly into the ferment if I don't have to, just another possible place for contamination.

 

[eric19312]

+1 tape with insulation over...


I use one of those plastic air pillows Amazon uses as packing material as my insulation. Important not to insulate the whole fermentor, else you will trap the heat and not be able to get rid f the excess heat from fermentation?

 

[bruin_ale]

nah, I have a jacket around the entire fermentor and it doesn't "trap" the heat all that much - I guess the top and bottom of the carboys are exposed, so it's not really the ENTIRE thing though.. It does take a little while to shed heat, but I keep the chamber much colder than needed and use heat tape warm each vessel to the exact temp I need. This way I can keep multiple carboys at different temps.

 

[brokebucket]

+1 tape with insulation over...


I use one of those plastic air pillows Amazon uses as packing material as my insulation. Important not to insulate the whole fermentor, else you will trap the heat and not be able to get rid f the excess heat from fermentation?

The thing is, if you have the t/c insultated along with the fermenter, you are getting actual beer temp, not a mix of air and beer temp. If you dont insulate, you are getting some kind of bastardized temp and not your real fermentation temp (which is what you really need to control).

My theory: The insulation will also help slow the rate of heat exchange so you are not getting alot of upward and downward spikes in your temp. With the controlled environment of the ferment chamber, you are also controlling it thru the whole process, so you dont get a whole lot of heat buildup to remove at once, it is a constant controlled process. Also, the ferm wrap is a gentle slow heating mechanism that would lose much heat to the chamber if it were colder than your desired temp, thus you would want to hold the heat to the fermenter.
The key is that you really dont care what temp the chamber is, as long as it maintains your fermentation temp correctly.

So no, insulating actually helps, not hinders the process.

 

[dawalkertiger]

This is helpful y'all. I have a solution until I get the chamber built. Hoping I can get my old freezer out of the room its in. It's so old and big and heavy, the room was kinda built around it! If I can, it will become the fermentation chamber using the STC-1000 and we'll get an upright freezer for food. That will leaver room for the eventual keezer for kegging.

 

[bruin_ale]

My theory: The insulation will also help slow the rate of heat exchange so you are not getting alot of upward and downward spikes in your temp. With the controlled environment of the ferment chamber, you are also controlling it thru the whole process, so you dont get a whole lot of heat buildup to remove at once, it is a constant controlled process. Also, the ferm wrap is a gentle slow heating mechanism that would lose much heat to the chamber if it were colder than your desired temp, thus you would want to hold the heat to the fermenter.
The key is that you really dont care what temp the chamber is, as long as it maintains your fermentation temp correctly.

So no, insulating actually helps, not hinders the process.

I concur.. I'll add that the fermwrap is sort of double sided, there's not a hot side and a cold side - so insulating around the fermwrap makes it more effective. Which was one of the main reasons I started insulating my fermentors in the first place.

 

[eric19312]

The thing is, if you have the t/c insultated along with the fermenter, you are getting actual beer temp, not a mix of air and beer temp. If you dont insulate, you are getting some kind of bastardized temp and not your real fermentation temp (which is what you really need to control).

Maybe you misunderstood me. I do insulate, but only the probe and about 3" in every direction from the probe. Am using stc to cause refrigerator to cool ambient when the insulated probe shows temp out of bounds. So I don't want to insulate the beer from ambient...else how would the refrigerator cool it... Am afraid if you insulate the fermentor in this situation you are asking for a runaway heat spike as the exothemic fermentation increases temp, accelerating fermentation, adding more heat....

Now if you can put some sort of chiller under your insulation, great, but then why would you even bother with the fridge?

 

[DPBISME]

I am brewing this weekend and the temp here in Virginia just leapoed from the 40s to the 80s.... I was looking for 60s to do a few batches.

My plan is to use the wet-towel/tee-shirt method to keep the beer cool the first few days...

AND

... once it starts bubbling to remove the airlock to allow some of the heat to escape with the CO2.

DPB

 

[eric19312]

... once it starts bubbling to remove the airlock to allow some of the heat to escape with the CO2.

DPB

Won't the heat escape with the co2 right through the lock?


Tee shirt should work well. You can also add a fan blowing on the shirt to pull off even more heat.

 

[scrambled]

Am I the only one who opens the carboy and sticks a sanitized thermometer into the wort? I don't do it alot but once or twice when fermenting gets going to see where my temps are settling and adjust my swamp cooler. After a couple days, I just monitor the temp of my swamp cooler water and figure I am within a couple degrees.

 

[BetterSense]

I think that the stickers are pretty accurate, certainly within +/- 1 degree C which is good enough for brewing purposes. I think a thermowell is overkill for fermentation.

 

[brokebucket]

Maybe you misunderstood me. I do insulate, but only the probe and about 3" in every direction from the probe. Am using stc to cause refrigerator to cool ambient when the insulated probe shows temp out of bounds. So I don't want to insulate the beer from ambient...else how would the refrigerator cool it... Am afraid if you insulate the fermentor in this situation you are asking for a runaway heat spike as the exothemic fermentation increases temp, accelerating fermentation, adding more heat....

Now if you can put some sort of chiller under your insulation, great, but then why would you even bother with the fridge?

I dont know who is more right, but I insulate the whole thing and do not have temp spikes. But if you need to raise temps, how do you do that?

 

[eric19312]

I dont know who is more right, but I insulate the whole thing and do not have temp spikes. But if you need to raise temps, how do you do that?

40W light bulb in the fermentation fridge. Had no issues in garage that got down to about 40 this winter. That's the beauty if the STC controller, it controls both the heater (light bulb) and the chiller (fridge coil).

Downside is I am only controlling temp of one fermenter. The other fermentor is sort of riding along. I always put the probe on the fresh batch as I think most of the potential damage from lack of control is in the first week when active fermentation is underway.

 

[balrog]

I have a little cube dorm fridge to cool, a little Lasko personal heater to heat, a 12v PC fan on a cellphone wall wort to circulate the air around a little stacked up 2" rigid foam board "chamber" with STC flashed with AlphaOmega's STC-1000+ firmware for °F and temp profile ramping. I set it to 1°F and during active ferm first few days I see the fridge cycling maybe 1.5 times per hour, 15 mins, to keep 63° in an ambient cellar 67° environment.

So it works great now. But will I be able to lager with this setup during the summer when cellar temp is 70 and I want to hold 50? Dunno. I've actually seen a thread somewhere on here where someone showed the dQ/dT calculation given 5G thermal mass and BTU fridge output but I just can't recall it.

I do remember reading that the temperature critical first few days of active fermentation is also during time when the yeast activity is roiling and boiling that wort, mixing it (and edge to center temps) quite well. Anytime other than that, you likely aren't trying to move temps very fast through that big 5G thermal mass anyway.