Poll: Fermentation chamber temperature probe placement

[liljimmynorton]

I actually tape mine(with insulation) to an extra keg of just water that I keep in the fermenter. This temperature remains contstant and does not swing like a fermenting beer would. I then adjust my temperature slightly lower the first few days of fermentation to counteract the heat being put off by the fermenting beer.

 

[vincemash]

I've tried about every method mentioned and finally settled on what I think is the ideal configuration:

1. Installed a muffin fan to circulate the air in all of my freezers and fridges. I run the fans continuously.

2. Controller probe placed so that it is in the air or attached to the side of the fridge if the cooling coils are not in the walls. IOW, not in contact with cooling surface.

3. I use a separate digital indoor/outdoor type thermometer to monitor the fermenter temps with the probe attached to the side of the fermenter and covered with a small piece of insulation. This traps the heat radiating from the fermenter and approximates the internal temperature while isolating the probe from the air temperature in the chamber. The single exception is my serving keggerator where I have the controller probe mounted directly in the air stream of the fan. I adjust the controller based on the temp of the poured beer out of the taps. No need for the separate thermometer in this case. I can't directly sample the beer in the fermenters, but I can do so out of the taps.

4. The analog Johnson controllers have a preset differential which IIRC is about 3 degress F and that works just fine. I set the digital one to a 5F differential and that also works just fine.

5. The fermenter temps are very stable with this method usually varying less than one degree F. I have found it necessary to dial the controllers down well below target temps during the first few days of fermentation when the high activity is generating a lot of heat. I then raise the temperature over several days once the activity slows. I have found that it is best to cool the wort well prior to pitching as once the high activity begins it is much more difficult to bring the temperature down.

I'm getting excellent results with this configuration. I have no controller probes in a containers of water. I have no controller probes inside the fermeter (with or without a thermowell). I've come to the conclusion that using the controller probe to regulate the air temp and also to monitor the fermenter temp is not the best way to do it, but according to Bobby, he is having success doing it that way so you might want to give it a try.

Thanks Catt, this makes alot of sense

 

[Catt22]

Vince,

It's very easy to test out the various possible configurations and decide for yourself what works best. The best thing I did was install the muffin fans to keep the air circulating. Most, but not all, refrigerators already have fans in them to move the cold air from the freezer compartment to the refrigerator section. Those are typically wired to run when the compressor is running. Some are also wired to run for a certain duration whenever the refrigerator door is opened. This works OK as is for fermentation purposes, but I prefer to hack the wiring and make the OEM fans run continuously if I'm using them for lagering.

 

[vincemash]

I have done some testing on this the past few days, I have a fan wired into my cooling and heating circuit so whenever cooling or heating is called on by the controller, the fan runs also, so here are my observations....large unresized pic here:

Scenario 1
I hung the probe in the air and put a separate thermometer probe insulated against the carboy and set the controller for a 4 degree difference, with this setting the compressor was attempting to come on before my compressor delay(10 minutes). The carboys were staying within .2 degrees F with this setup.
Advantage: carboys temp most stable
Disadvantage: Compressor was running every 10 minutes. During fermentation you would have to manually adjust the controller to compensate for heat produced in fermenting wort.

Scenario 2
I hung the separate temperature probe in the air and placed the controller probe insulated against the carboy, I set the controller for a .3 degree C (that was the lowest it would go) difference, with this setting the compressor was cycling at a much longer interval (maybe 30-40 minutes). The air in the chamber was varying upwards of 10 degrees F during the cycles.

Advantage: you can set and forget and the controller will control the temp of the fermenting wort. Less cycling of the compressor, longer life of freezer and most likely more economical for power consumption.
Disadvantage: Large temp swings inside the compartment, although due to the large thermal mass of the wort this doesn't seem to be a problem

I brewed an Oktoberfest last night (with Kolsch WLP029 yeast) and set the controller to 63 degrees with a .3 difference and insulated the probe against the fermenter wall.....I will report back tonight once fermentation takes off and I see how things are performing.

 

[Catt22]

Vince,

Try Scenario No. 1 again, only keep the fan running continuously and set the differential to 5 degrees. Set the Asd to the max 12 minutes. Keep everything else the same. I think you will find that the fermenter temp will vary less than 1 degree F. The compressor on/off cycle will vary considerably with the ambient air temperature. You might want to do the same with Scenario No. 2 and see what happens. You could probably approximate Scenario No. 2 if you used Scenario No. 1 by increasing the differential setting to maybe 10 degrees.

With any of these tests, you really need to run them for at least 48 hours. It will probably take that long for everything to stabilize when making adjustments. The fermenter temp takes a very long time to change much. Longer than you might guess.

Good show and good information!

 

[Layne]

I tape the probe to the outside of the fermenter, with a small folded piece of papertowel between the tape and the probe to keep the probe from getting sticky.
Note: Now that I ferment in corneys, I am getting a truer reading, than with carboys. Thermal transfer and all

 

[vincemash]

Vince,

The compressor on/off cycle will vary considerably with the ambient air temperature.

agree....it has been ambient-ly hot as hell this summer.....and my freezer resides in the "non climate controlled " garage

 

[Catt22]

Note: Now that I ferment in corneys, I am getting a truer reading, than with carboys. Thermal transfer and all

And you know this how? I would think there would be little difference if any at all between the two.

 

[SankePankey]

Lets look at it from a pro's perspective. They all use thermowells inside their fermenters (+ usual disclaimer for speaking in absolutes). Most do not care about the air temp in the ferm room and if so only to take some load off the glycol system.

They do however have jacketed cooling systems that are wrapped directly around the tank and are not trying to gleam relative temp from the atmosphere while worrying about overshoot.

So, I think that suggests that if you have a ferm chamber that fits your primary "Like a Glove" (-said like Jim Carrey), then a thermowell is great. My converted Sanke is in a 7.2 cu chest freezer w/ not much more room for anything else. I don't experience much overshoot than 1 degree at times and can program my LOVE to take care of that. Certainly easier than screwing with bungee cords.

 

[Layne]

And you know this how? I would think there would be little difference if any at all between the two.

Maybe more asumption than fact. But I assume that the stainless corney would transfer the temp better/faster than the glass carboy.
I guess it probably is very little difference anyway.

 

[Catt22]

Maybe more asumption than fact. But I assume that the stainless corney would transfer the temp better/faster than the glass carboy.
I guess it probably is very little difference anyway.

I kind of figured it was mostly a hunch. Yeah, the differences in the thermal conductivity of the containers probably makes little difference once the temperatures stabilize. There might be some lag difference when ramping up or down though, but I suspect it would be rather small and insignificant.

 

[Catt22]

Lets look at it from a pro's perspective. They all use thermowells inside their fermenters (+ usual disclaimer for speaking in absolutes). Most do not care about the air temp in the ferm room and if so only to take some load off the glycol system.

They do however have jacketed cooling systems that are wrapped directly around the tank and are not trying to gleam relative temp from the atmosphere while worrying about overshoot.

So, I think that suggests that if you have a ferm chamber that fits your primary "Like a Glove" (-said like Jim Carrey), then a thermowell is great. My converted Sanke is in a 7.2 cu chest freezer w/ not much more room for anything else. I don't experience much overshoot than 1 degree at times and can program my LOVE to take care of that. Certainly easier than screwing with bungee cords.

IMO, our relatively very small fridge and freezer fermentation chambers have almost nothing in common with the very glycol cooled jacketed professional fermenters. Your fermenter is still surrounded by air, just like those most of us use. I was not aware that you could program a Love controller at all. I thought they were just "dumb" controllers much like the Ronco and Johnson digitals. Screwing around with a thermowell is much more of a hassle than a bungee ever could be.

 

[SpanishCastleAle]

Screwing around with a thermowell is much more of a hassle than a bungee ever could be.

It may be a tiny bit more hassle but I use a thermowell and it's almost as easy as using a plain ole airlock. Carboy cap, thermowell in the 'straight' port, blow-off tubing on the 'angled' port (it all fits perfect, this is all assembled while in the Starsan bucket), put on carboy, stick the wires down into the thermowell, done. Other than the Starsan soak time it takes all of about 30 seconds.

 

[wildwest450]

I've tried it all of those ways and having the controller probe touching the wall of the fermenter is the best compromise.

Bingo, end of story, we have a winner. Just tape it to the side, couldn't be easier.

 

[bwiens]

I use the thermowell in my fermenters, which are 15.5g sanke kegs. My chamber is a stand alone cabinet that is ducted to my keezer. My controller runs a fan that pulls the cold air into the chamber from the freezer.

After 2 weeks in the sanke I move the beer to corny kegs and leave them in the chamber for 2 more weeks, during this time, if there are no other sankes in the chamber, the prob hangs free in the air.

I use a 1 degree set point when in the thermowell and a 2 degree when in the air. The keezer is set to 33* and it functions as my cold conditioning and serving location.

 

[Catt22]

Bingo, end of story, we have a winner. Just tape it to the side, couldn't be easier.

+1 Tape, bungee or even Velcro FTW. I'm in the process of upgrading to Velcro attachment for all of mine. Just shot two Velcrows this morning. Now I just got to skin the prickly little suckers.

 

[Catt22]

It may be a tiny bit more hassle but I use a thermowell and it's almost as easy as using a plain ole airlock. Carboy cap, thermowell in the 'straight' port, blow-off tubing on the 'angled' port (it all fits perfect, this is all assembled while in the Starsan bucket), put on carboy, stick the wires down into the thermowell, done. Other than the Starsan soak time it takes all of about 30 seconds.

Sounds an awful lot like a small hassle to me and might be a double hassle if using both carboys and plastic bucket fermenters which is what I have.

 

[SpanishCastleAle]

Sounds an awful lot like a small hassle to me and might be a double hassle if using both carboys and plastic bucket fermenters which is what I have.

If you were to write out a step-by-step procedure I can assure you using a bungee along with an airlock would seem like a small hassle. Like I said, it takes all of 30 seconds...and it would take 20 seconds if it were just a 3-pc airlock (not even including the bungee futzing).

The thermowell/cap assembly takes the place of an airlock, which you still have to deal with when using the bungee. It's no more hassle, really.

 

[Catt22]

Well, just the fact that it requires a a thermowell moves it into the more hassle realm for me. I'm still not convinced that the probe in a thermowell is the better configuration. I'm getting excellent results with the controller probe in the air and the thermometer probe attached to the outside of the fermenter. Often I don't even attach the probe to the fermenter. Instead, I use the carboy handle to hold it in place or just lay it on top of the bucket fermenter lids. I do cover them with the bubble foil insulation whichever way I do it though. This is so easy and effective, I see no advantage in doing it any other way. IMO, a fan in the freezer is the key to success when using them as fermentation chambers.

 

[SpanishCastleAle]

Well, just the fact that it requires a a thermowell moves it into the more hassle realm for me. I'm still not convinced that the probe in a thermowell is the better configuration. I'm getting excellent results with the controller probe in the air and the thermometer probe attached to the outside of the fermenter. Often I don't even attach the probe to the fermenter. Instead, I use the carboy handle to hold it in place or just lay it on top of the bucket fermenter lids. I do cover them with the bubble foil insulation whichever way I do it though. This is so easy and effective, I see no advantage in doing it any other way. IMO, a fan in the freezer is the key to success when using them as fermentation chambers.

The point is that it's redic easy using any number of methods; some of which are comparable in terms of simplicity, others not so much. Maintaining ferm temps just isn't that hard. KISS rule ftw.

I only use a chest freezer for serving/conditioning and obv don't need a fan in there for that. I suppose a fan could be necessary in a chest freezer for fermenting but it's def not necessary in a fridge and just adds complexity. Still not sure why you need a fan.

 

[ILOVEBEER]

How about using a piece of pottery sponge (the green stuff they use to hold fake flowers up in a pot) It is very porous, easy to penetrate and cheap?

 

[SankePankey]

It is very porous, easy to penetrate and cheap

like a ... a.....oh nevermind.

 

[ILOVEBEER]

haha I knew it!

 

[Catt22]

IMO, having a fan in a serving freezer is a major improvement. The air in the freezer will be much warmer near the top where the beer lines and taps are typically located. The temperature differential can be as much as 10-15 deg F from top to bottom. I get much less foaming when I keep the beer lines and taps chilled. I think a fan is more important in a serving freezer than in a fermentation chamber, but they work very well for both. Most fridges have already have a fan to move the air from the freezer compartment to the refrigerator section. Not all, but most do. Without a fan, the only air movement would be through convection currents. When a freezer is used as a freezer, the entire box is usually at sub zero temps so the air circulation is of no concern. It's a much different situation maintaining uniform temps at fermentation, serving or even lagering temps which are considerably above zero. I was never happy with my serving freezer performance before the fan installation. It was a very big improvement. I'm surprised that using a fan this way is not universally embraced. It's a dramatic difference.

 

[Catt22]

How about using a piece of pottery sponge (the green stuff they use to hold fake flowers up in a pot) It is very porous, easy to penetrate and cheap?

Yes, that would probably work, but for best results you only want to insulate the side away from the fermenter. IOW, you would only half embed the probe. I've used lots of different stuff including a piece of cardboard, a wash cloth, bubble foil insulation and styrofoam. Just about anything will work to some degree. I settled on the bubble foil stuff as it is impervious to moisture, insulates well, it's cheap and I had some laying around.

 

[ILOVEBEER]

So the best place to put the probe is taped to the side of the freezer, but insulated between the probe and the freezer wall?

 

[Catt22]

So the best place to put the probe is taped to the side of the freezer, but insulated between the probe and the freezer wall?

No. That does not work well as the cooling coils are embedded in the wall of the freezer. Attach it to the side of the fermenter or mount it away from the walls in the air. I have mine mounted in the air and use a separate thermometer to measure the fermetner temp. I cover the thermometer probe with some insulation (any type will work. Foam rubber, bubble foil, etc). I don't cover the controller probe with anything at all. You can also do it Bobby's way with similar results by attaching the controller probe to the fermenter and covering it with insulation the same way.

 

[RDWHAHB]

Haven't visited the thread in a while. Cat22-Yes, I do have real experience. I have a ferm chamber that fits 2 carboys. I use a thermowell. Over shoot isn't too much of a biggie for me because the thermal capacity of air (6ft^3?) is so much less than 5 gal of beer (~.7ft^3). Even if I shut the glycol pump off when the chamber (air) is overshot by 20*F, and the thermal xfer between beer & air was perfect, the beer would not overshoot much (1*F?). If interested, I'll run some actual calcs. Those numbers are a guess. I also do industrial controls for my day job.

I am looking at a rebuild which will log both carboy & ambient temps. I am excited to see that.

Cheers, Jeffro

 

[Catt22]

Apparently you have a rather unique fermentation chamber with the glycol chilling etc. I'm sure that it operates much differently than a chest freezer would. With your expertise, I would think that your numbers would be more than just a guess. With the freezers, it's not so much the thermal capacity of the air inside as it is the thermal capacity of the freezer walls and evaporator coils which continue to cool the air for quite a while after the compressors shut down. IMO, the lag in the response time of a thermostat would increase with a probe in a thermowell and this would result in wider temp swings of both the air and the wort. I suppose this could be mitigated if you maintained a very tight differential, but I suspect the swing would exceed the one degree variance I am able to maintain with the controller probe in the air. I don't care what the air temps in the freezer is or how much it swings. I am only interested in maintaining stable fermentation temps and plus or minus a couple of degrees is plenty good enough for my purposes. I actually have my controller set to a fairly wide 5 degree differential. The compressor typically runs about 1/3rd of the time. This is with the fan running continuously. I think I could improve the efficiency a lot by adding some insulation to the inside of the wooden collar and the lid. I'm not sure what kind, if any, insulation is inside the lid behind the plastic liner. I know for sure the 2 X 6 wooden collar has a low R value and it's a major source of heat gain.

 

[patrck17]

Sorry to bring the thread back from the dead but...

I wish somebody would get something like this and do some profiles. Would be interesting to see some comparisons of the wort temp vs thermowell temp vs chamber air temp etc etc etc. Tempted to buy one myself but I don't want to have to drill anymore holes in my keezer.

http://www.pcsensor.com/index.php?_a=viewProd&productId=29

(I link this product cause it seems far more affordable than the alternative thermocouple DAQ's I've seen which typically range into the hundreds.)

 

[vincemash]

Sorry to bring the thread back from the dead but...

I wish somebody would get something like this and do some profiles. Would be interesting to see some comparisons of the wort temp vs thermowell temp vs chamber air temp etc etc etc. Tempted to buy one myself but I don't want to have to drill anymore holes in my keezer.

http://www.pcsensor.com/index.php?_a=viewProd&productId=29

(I link this product cause it seems far more affordable than the alternative thermocouple DAQ's I've seen which typically range into the hundreds.)

I just brewed a hefe on saturday and wanted to keep it at 65, I have my controller probe insulated against the fermenter wall, and a separate temp probe in the air. I probably should have written down the readings daily but I did take note that during the first couple days of aggressive fermentation the air temperature was around 52 to keep the fermenters at 65....the air temperature slowly goes up as fermentation subsides....today its hovering around 61

 

[patrck17]

I just brewed a hefe on saturday and wanted to keep it at 65, I have my controller probe insulated against the fermenter wall, and a separate temp probe in the air. I probably should have written down the readings daily but I did take note that during the first couple days of aggressive fermentation the air temperature was around 52 to keep the fermenters at 65....the air temperature slowly goes up as fermentation subsides....today its hovering around 61

This is very informative feedback. Thanks for the info. I currently have my probe mounted between a paper towel and the carboy wall. I don't imagine the insulation is as good as it could be but I imagine it is getting the job done.

 

[mthompson]

I voted for "insulated on the side of fermenter", and here is why...

I set up my fermentation chamber with a Ranco controller (b-day present) and put in the first batch on Jan. 1. I set the controller to 65*F with 1*F differential and made an insulated 'pouch' for the thermistor out of a few layers of cotton roll and a paper backing, then loosely duct taped it to the side of the bucket, as to not squish the cotton and reduce insulation properties, with thermistor in direct contact to bucket.

I have been tracking temps in each of four locations with two of these traceable thermometers -

1. ambient air temp as soon as I open door,
2. inside tub of sanitizer next to fermenter for blow-off tube,
3. inside the fermenter (sanitized from second measurement, remove air lock, test, replace lock),
4. inside the insulated pouch next to the thermistor

Today, at the height of fermentation (judged by the copious amounts of CO2 continually bubbling in the sanitizer and the fridge cycling on once every 20-30 minutes), the four measurements read (as soon as cycle turned off):

1. ambient air temp - 58.2*F,
2. inside sanitizer - 64.1*F,
3. inside the fermenter - 65.7*F,
4. inside the insulated pouch - 65.2*F
5. Ranco controller - cycles on when it displays 66*F and turns off when it displays 65*F

**each thermometer read the same temperature each time at each location

I will test the same temperatures after fermentation subsides a bit more....and maybe other can take similar readings using the various methods and post up the results. It's the only real way to settle on the "best" way to measure and control fermenter temperatures

 

[SpanishCastleAle]

I think it's worth mentioning that any container full of liquid, whether it be a carboy/corny full of beer or a jar with water in it, will always tend to be more towards the outside temp than the middle of any 'differential'. So if your controller turns ON at say 64* F and OFF at 68* F and the temp outside the fridge is significantly warmer than that; the middle of the differential is 66* F but a container of liquid in the fridge will be warmer than 66* F. The reason is because as soon as that controller shuts OFF at 64* F, the temp immediately starts to rise (and relatively quickly). As the temp gets closer to 68* F, the temp is rising quite a bit slower so the container of liquid spends way more time above 66* F than below it.

I only mention this because not all of the increased temp inside a fermenter is always due to the heat of fermentation, some of that is often just due to what I described above.

 

[Randar]

Not to restart the debate, but I originally voted for the thermowell option. Since that time I have seen the light and taping to the side of the container works marvelously for me. It is not really measuring ambient air temp. Since I ferment in Sankes there is some decent thermal conductance so while the center of the keg may be a couple degrees warmer during highly active fermentation, I can choose to adjust for this (or not) and control the temps very accurately, even in a shoddily-insulated fermentation chamber. I think this is also very similar to a glycol jacketed fermentor. The thermowells in 30 BBL fermentors do not reach to the perfect center of the tank, nor would that give extensive benefit (since the wort/beer closest to the walls that is absorbing the thermal transfer from the glycol system could be many degrees cooler).

 

[EarthBound]

Thanks to all for the tips. I was about to install a thermowell and was immediately stopped dead in my tracks after reading this thread.

"Insulated against the fermenter wall" for me!

 

[hollywoodbrew]

I'm using a thermowell for my controller probe. I get a swing of about 3-4 degrees every 8 hours or so. The freezer turns on 3 times a day so I like how its really easy on the compressor, and uses less electricity.

Is a variation of 3-4 degrees okay or will that make off flavors?

 

[Salmonhouse]

I believed that the air was the most appropriate place for the temp probe when i first hooked up my controller and was shot down by opinions in the 'ebay diy controller' forum. I then went to a thermowell. Now that i have a thermowell i find that my heater does overheat the wort to where my compressor has to kick in. I don't think i should be needing my compressor at all since its colder outside than in my chamber. Maybe my chamber is too well insulated or my heater is over sized.

I think i'm going to try to use the thermowell initially for active fermentation and then use the air. Either that or use the air entirely and monitor the temp in my thermowell with a separate thermometer and compensate my controller accordingly.

 

[Catt22]

Either that or use the air entirely and monitor the temp in my thermowell with a separate thermometer and compensate my controller accordingly.

That's exactly how I do it. I also have a muffin fan running continuously which circulates the air around the fermenter cooling it more effectively (or heating). I use an ordinary indoor/outdoor digital thermometer with min/max memory. The min/max readings tell you what the actual temp swing is. Running with a 4 degree differential the min/max variance is only 1.3 degrees.

 

[Salmonhouse]

I think i'm also going to play with adjusting the thermostat on the heater.