Poll: Fermentation chamber temperature probe placement

[Catt22]

With due respect, I couldn't disagree with you more as to how to control fermentation temp. The ONLY thing you can directly control is the air temperature within the chamber. Keeping that as near to your set point temp is the only way to minimize the ferment temp swings which is the primary thing you want to avoid anyway. With the probe monitoring the fermenting wort the control will not kick on until there is a warming of the wort and then a big delay until it once again falls to the set point temp. However, with the control probe monitoring the chamber temperature the wort has a much greater chance to remain stable as the chamber quickly returns to set point temp.

+1 IMO, you have it right. This is also the reason I suggest attaching a separate thermometer probe to the side of the fermenter and insulating it from the chamber air. The controller probe in the air will register fairly wide temperature swings, but without the separate thermometer you can only guess at what the average fermenter temp might be. I can maintain a very steady fermenter temp using this method.

 

[vincemash]

+1 IMO, you have it right. This is also the reason I suggest attaching a separate thermometer probe to the side of the fermenter and insulating it from the chamber air. The controller probe in the air will register fairly wide temperature swings, but without the separate thermometer you can only guess at what the average fermenter temp might be. I can maintain a very steady fermenter temp using this method.

that is my plan....hang the probe for the controller in the air, and then attach a separate thermometer to the fermenter.....then I can check the fermenter temp daily and adjust accordingly

 

[Bensiff]

I have one in the beer and one in the air. The beer probe controls heat and the air probe controls cold. I set the heat to kick on 1 degree below desired ferment temp and set the cold to keep the ambient air temp a few degrees below desired ferment temp the first few days of fermentation to help push down temp during the high exothermic phase and then put at desired temp the rest of the time.

 

[Catt22]

I have one in the beer and one in the air. The beer probe controls heat and the air probe controls cold. I set the heat to kick on 1 degree below desired ferment temp and set the cold to keep the ambient air temp a few degrees below desired ferment temp the first few days of fermentation to help push down temp during the high exothermic phase and then put at desired temp the rest of the time.

That's the oddest method I've heard of so far, but I would bet there are some others out there somewhere that might top it. There just have to be.

 

[Catt22]

1) PID doesn't kill cooling equipment, short cycly times do. Short cycles should be avoided with t-stats as well.
2) PID is not overkill if you are experincng wild over/undershoots with your temp control. A good PID can be had for the same $$ as a ranco/johnson.
3) you want to cntrl the fermentation temp, not the air temp. Measuring anything other thanthe fermenting beer's temp introduces error.

Do you actually have fridges or freezers that you control with a PID or are you talking in theory only? You'll be the first that I've heard using a PID for this if you do. I'm kinda wondering why this is not more common if the costs are a push and the performance so much better.

 

[bendavanza]

Cat22:
Not mine, but:
info on PID - fridge - freezer.
https://www.homebrewtalk.com/f51/how-wire-auber-syl-2362a2-pid-fridge-157513/

 

[Catt22]

Cat22:
Not mine, but:
info on PID - fridge - freezer.
https://www.homebrewtalk.com/f51/how-wire-auber-syl-2362a2-pid-fridge-157513/

Yeah, I now I do remember that thread. Taking another look at it I notice that basically the Auber PID parameters were selected to make it operate essentially just like the digital Johnson's, Ranco & Love's. IOW, there's not much in the way of Integration or Differentiation going on if you keep those in the null mode. That would be the "I" & the "D" part of PID IIRC. Looks to me like only a setpoint, a temperature differential and an anti-short cycle delay were used and nothing else. I can do all of that with my digital Johnson and it's plug and play. Perhaps I'm missing something.

 

[vincemash]

I've tried it all of those ways and having the controller probe touching the wall of the fermenter is the best compromise. It is affected by both the inside air as well as the fermenting wort. If it's in the center of wort in a thermowell, you'll undershoot the temp. The fridge will become a brick of ice before 5 gallons reacts. Putting the probe in a glass of water is the worst because it is as isolated from the wort temp as you can get. If the ferment is very active, it will be hotter than you want and take a long time for that heat to register in the satellite liquid.

Bobby

So with your method you just have the probe touching the fermenter wall but do not insulate it from the surrounding air?

 

[Catt22]

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.

 

[Bobby_M]

Sorry I wasn't clear, the probe goes against the side of the fermenter and is held there with a bungie cord. I slip a 3" x 3" piece of reflectix between the cord and probe as primitive insulation. I suppose you could use a piece of bubble wrap or even a kitchen sponge.

The main purpose for me is to make sure the probe senses any heat coming from an aggressive fermentation but also have it react quickly. A deep thermowell would account for the first goal but not the second. An alternative is to have a thermowell in the wort but very close to the outside wall. Same effect.

Once the ferment subsides, this is less important. Dangling in the open air would be fine for that as long as you don't open the door many times a day.

 

[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.