Johnson A419, Freezer and Thermowell Help

Hi everyone. I'm hoping to find someone around here that has the same setup as listed in the title and pick their brain. I have a Johnson A419 controller, chest freezer and thermo-well for my fermentation chamber. I have the controller set to 1 degree difference and my temp @ 69. I'm experiencing problems with the freezer running for too long and once the desired temp is reached it shuts off but keeps cooling the beer.

Basically I'm experiencing temp swings of about 4-5 degrees every time it runs. What I'm wondering is why the differential can't be set to 0, so once the desired temp has been achieved the freezer will shut off. I had it set @ 69 earlier and it kicked on @ 68. Is there a setting that I'm missing or something I can do so I don't experience such a drastic fluctuation in temps? I really wanted to ferment ales @ the mid 60's range but unfortunately I can't because the actual temp will get down to the low 60's.

Any recommendations or feedback would be more than appreciated.

Don't put the controller probe in the thermowell. This causes too much lag. Mount the probe midway down the wall of the freezer. Use a separate thermometer to monitor the wort temperature. Adjust the controller until the fermenter thermometer reads the desired temp. Allow sufficient time for the wort temp to adjust and stabilize before making additional adjustments. This may take quite awhile. Several hours at least and maybe longer than that. Don't worry about the specific set point temperature. Set the differential to 3 deg F or more. One degree is too tight and will prematurely wear out the freezer compressor. You don't want it to cycle too frequently. I use an indorr/outdoor wireless digital thermometer to monitor my fermenter temp. This allows me to monitor the fermenter temp without opening the freezer lid.

Really? No thermowell in the carboy? I was really hoping to use that so I could get the most accurate temps possible. As it stands the freezer only cycles roughly once every 6 hours so premature wear shouldn't be a problem. Its just the temperature fluctuation is greater than what I anticipated. My whole premise of using the thermowell was for vigorous fermentations and controlling their temperature. I figured what better way to keep the temp where I want it than to take a reading from the center of the liquid. Was keeping the temp within 1 or 2 degrees completely unrealistic? I'm starting to think I should have gotten a refrigerator rather than a freezer?

I had something long written out here then noticed you have the a419, not the a19... oops

Anyway...I think your best bet would be to stick a probe type thermometer in your thermowell, the controller probe in the air in your freezer, monitor your fermentation temps and adjust the controller to maintain that.

I think you are missing the point. The reason that the freezer only cycles every six hours is because it takes that long for the wort to warm up enough to make the controller turn on. This is why you do not want the probe in the thermowell on the fermenter.

Place the probe in the air space of the freezer. Use a separate thermometer for the fermenter. Do it this way and your wort temperature will only fluctuate a degree or two at most.

You are trying to do two things with one instrument the way you have it now and it won't work. You should only be concerned with the average temperature of the wort in the fermenter and that is what you want to monitor. Don't worry about the air temperature fluctuations in the freezer. The air temp only very slowly affects the wort temperature.

The controller differential setting will only regulate the freezer air temp swing, not the wort temp swing.

A freezer is typically the better choice for most of our home brewing purposes. Refrigerators will work, but freezers work better and more efficiently for us.

Trust me on this (and MMW too). Change the probe as I suggest and your problem will be solved and your wort will stay at the temperature you want it to be.

1. Probe in the freezer air
2. Separate thermometer in the thermowell
3. Set the A419 differential to 3 deg. F or wider. and the set point to your desired wort temp.
4. Allow time for wort temp to stabilize before adjusting the controller further
5. Adjust controller as needed

Adjust the controller according to the thermometer in the thermowell, NOT according to the read out on the controller.

Just for another data point, I will disagree with Catt22 and MMW. Your goal is to control the fermentation temps. IMHO, it makes most sense to put the thermocouple or controller temperature probe in the thermowell. I use two chest freezers for fermentation. One is controlled with a Ranco and the other is controlled with a Johnson A419. The controller temp probes are in thermowells. I have the Johnson A419 set for a 1F differential just as you describe. I typically get a one degree overshoot on the cold end, especially if I am fermenting lagers. For example, if I have my temp set at 66F, the freezer will kick on when the wort temp hits 68F. It then chills to 66F and then shuts off. However the temp will often drift 1F to 65F. So instead of a 2F range it is more like 3F. I never get more than a 3F differential, even when fermenting lagers at 50F. I think this approach will be tighter than controlling the ambient temp inside the freezer.
I wonder if you have your A419 set up properly. You want it set up in the "Cooling, Cut-out mode". In this mode, when your temp is 2F (providing differential is set at 1F) above set point, the freezer will be turned on and when the temp cools down to the set point, the freezer will be turned off. Based on what you describe in your initial post, I think you may have it set up in the "Cooling, Cut-in mode", which according to the owners manual, is the factory default setting. Changing the mode involves changing some jumpers inside the controller. The owners manual describes the process well.
Good luck!

I was just going to start a topic on this and did an advanced search and found this thread.

I need to purchase another temp control unit. I have an analog (dial) type and thought I would try a digital with a Thermowell to get more accurate fermentation control.

They advertise the Thermowell for glass carboys. I assume they should work on a bucket or Better Bottle as well, right?

Is the Thermowell a good investment when coupled with the Digital-temp- control unit?

Pro's and Con's?

Rob

When i'm using glass or stainless carboys I use a long stainless tubing with a plug Tigged in the end for the thermal well with a LM34 temp probe potted in transistor thermal paste with the probe dead centered in the carboy. No temp delays instant readings, not like your temp swings of 75 degrees your just maintaining 1-2 degrees of control. A solid temp signal no matter the reaction in the carboy which will create different heat with different types of biers being fermented.

I agree that having the probe in the carboy will have too much lag time - due to the thermal mass of the liquid, by the time the probe sees a temp. change, the air in the freezer is way too cold. I don't think it matters at all whether the controller is set for cut-in or cut-out, except that one will operate just below and the other just above the set point.
I use a chest freezer with a A419. I have my sensor inside an empty White Labs vial (drilled a hole thru the plastic top) with a small round piece of cardboard with a hole in it to keep the sensor from contacting the wall of the vial. The vial is not in the carboy, but just out in the air. This provides enough lag to keep the freezer from cycling too frequently and keeps the liquid in the carboy at a constant temp. I use a differential of one degree and the fermometer on my carboy holds a rock solid steady temperature. You could probably achieve the same lag by simply putting the probe out in the air and setting a larger differential, though I haven't tried that.

DeafSmith said:

I agree that having the probe in the carboy will have too much lag time - due to the thermal mass of the liquid, by the time the probe sees a temp. change, the air in the freezer is way too cold. I don't think it matters at all whether the controller is set for cut-in or cut-out, except that one will operate just below and the other just above the set point.
I use a chest freezer with a A419. I have my sensor inside an empty White Labs vial (drilled a hole thru the plastic top) with a small round piece of cardboard with a hole in it to keep the sensor from contacting the wall of the vial. The vial is not in the carboy, but just out in the air. This provides enough lag to keep the freezer from cycling too frequently and keeps the liquid in the carboy at a constant temp. I use a differential of one degree and the fermometer on my carboy holds a rock solid steady temperature. You could probably achieve the same lag by simply putting the probe out in the air and setting a larger differential, though I haven't tried that.

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+10,000 I agree completely and I pretty much use the same method. My A419 probe is taped to the freezer wall at mid-keg level. I have a separate wireless thermometer sensor attached to the carboy. I adjust the controller Set Point according to the carboy monitor thermometer. The fermentation temperature is rock steady +/- 1 deg at most. IMO, using a thermowell & controller probe in the fermenter is the wrong way to do it. I don't understand why this is not obvious to everyone. It takes forever to change the temperature of 5 gallons of beer and with big temp swings inside the freezer it's unlikely the beer will be at a uniform temperature throughout.

BrewBeemer said:

When i'm using glass or stainless carboys I use a long stainless tubing with a plug Tigged in the end for the thermal well with a LM34 temp probe potted in transistor thermal paste with the probe dead centered in the carboy. No temp delays instant readings, not like your temp swings are 75 degrees your just maintaining 1-2 degrees of control. A solid temp signal no matter the reaction in the carboy which will create different heat with different types of biers being fermented.

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Beemer, I am a electronic designer, so i know exactly what you are saying. But how many folks on here do you think know what an LM34 is? Come on. WTF.

The walls in my freezer get pretty damn cold when the thing cycles on. For this reason, I always tape the temp controller sensor to the active carboy.

I think the thermowell is ideal.

Take this for what it's worth, but the best place for the controller probe is taped to the side of the fermenter with a moderate insulator on the outside like a 4" square of reflectix. You've found the problem with the thermowell. By the time the heat is pulled out of the center of a 5 gallon column, everything in the freezer is frozen and there's a ton of carryover. Taping to the side measure the outside perimeter of the beer which reacts quicker. Out in the open air isn't perfect either because it cuts off a bit too early.

passedpawn said:

Beemer, I am a electronic designer, so i know exactly what you are saying. But how many folks on here do you think know what an LM34 is? Come on. WTF.

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Thanks passedpawn; you understand where i'm coming from with my way of thinking on this matter of temp control.
The LM34 is no special secret rare item from NASA.

My reply adding my 2 cents worth is wanting to keep the fermenting chemical reaction temperture increase under control in the center core of the fermenter, this is a important temperture to me not to let go wild. Different biers will give off different heat BTU chemical reaction amounts. This is more important than the air temp inside the fermenting refrigerator's interior air in my book as it will stablize to a rather close temperture to the desired core temp inside the fermenter if the refrigerators temp control is set just below the fermenters center temp probe temp. I'm not making ice in the refrigerator. Stupid me for not knowing how slow the thermal conductivity of water or a liquid is vs air, wort or fermenting bier until this thread. I learned something new. That would also make 1,300 horsepower Porsche's that were air cooled more able to pull away more engine BTU heat than the water cooled Porsche's plus The harley "V" Rods also are all going the wrong way with their high horsepower motors going to water cooling vs air and just adding extra weight. (leave the EPA out of this reply). I wasn't aware air can pull more BTU's of heat energy away faster than a liquid?
What do I know just a dumb ass electrician and electronics hobby tinkerer that can let the smoke out now and then but I try?
I'll will still maintain my fermenting tempertures inside my fermenters central core during the temperture increase due to the fermentation temperture increase process. Call me all wrong as it's only me and my friends that drink my efforts in brewing and enjoy it without any complaints.
I must add that I received the used LM34 temp probes from another fellow brewing member Derrin some months ago so I can not take 100% credit or any credit at all for using then on my fermenter. Derrin was kind enough to ship me a pair of used ones for my use and learning. BTW thanks again Derrin as i'm enjoying and learning a lot from them, they are great allowing me to free up the BCS-460 on the brewer with the fermenters at the other house. I owe ya one bro, thanks Derrin for sharing your electronics knowledge. Carl.....

passedpawn said:

The walls in my freezer get pretty damn cold when the thing cycles on. For this reason, I always tape the temp controller sensor to the active carboy.

I think the thermowell is ideal.

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Yes, good point. I have four refrigerators and two freezers including one upright. The freezer I use for serving is the only one which has coolant lines in the walls, so I simply suspend the controller probe in the air for that one and for the others I tape it to a wall mostly to keep it out of the way.

Two of the refrigerators are dedicated lagering chambers kept mostly at 29 F for extended periods. Two others I use for fermenting ales. The upright I use for cold storage of my bottled beers and the chest is for serving kegged beers. This arrangement changes on an as needed basis. I'm using one A419 Johnson controller and five of the analog type. None using thermowells. The beers have been doing very well in recent competitions, so I must be doing something right.

Bobby_M said:

By the time the heat is pulled out of the center of a 5 gallon column, everything in the freezer is frozen and there's a ton of carryover. Taping to the side measure the outside perimeter of the beer which reacts quicker. Out in the open air isn't perfect either because it cuts off a bit too early.

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Bobby_M; why have the main freezer set to "freezer is frozen" with the freezers internal temp probe adjustment?
Why not have the freezer's temp probe set a couple degrees colder than your desired set temp you want in the center core of your fermenter plus use the deep well temp probe in the center core of the fermenter where the heat will be generated the most? With this center fermenter core temp probe in series with the freezers temp probe you will reach your frementers central core temp without having "the freezer is frozen" problem and still have full control of the fermenter's core temperature with the temperature you have set or want. Yes your freezer will be cycling until all temps including the fermenter's center core is reached, this will happen with just a in freezer temp probe or one taped to the side of the fermenter or carboy also. The conductivity of a glass carboy is lower than a stainless fermenter causing more freezer compressor cooling cycles alone.

Between reply #11 and 12 the Sponsored Add by THERM-X of California in Hayward is 15 miles away from me, I must check them out. Note to self, add to favorites. Thanks for that posting HBT forum..

What about having your temp probe in a glass jar of Star san like this? When I check the ambient temp inside and the temp in the glass jar after allowing time to equalize (so to speak) the temps are within 1 degree of each other. My Star San temp registers between 59 after it cycles off to a high of 62 and then it kicks on.

Bobby is it better to bubble wrap my probe to the side of the carboy than this method? I guess I need to remove the thermowell from my shopping cart? (still waiting to pull the trigger).

Yambor44 said:

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What are those white things sitting on top of your fermenters?

Catt22 said:

What are those white things sitting on top of your fermenters?

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EVA-DRY Mini Dehumidifier

Just another big +1 on Catt22's comments. It's really common sense when you think through the physics involved. Thermowells are for managing heat wraps in the Winter.

I use a thermowell in a chest freezer and it controls to +/- 2 deg of my setpoint. If I want a target SP of 53, I set the controller SP to 54. This way it gets to 54 and turns on. It may go up to 55, but never higher. It then cools to below 54, sometimes as low as 51.

Everyone is correct in that puting the temp probe on the outside of the carboy will control temp much more precisely, but it is only controlling to that specific location, not beer temp which could be warmer. (if you could measure the beer temp as well as control to the outside of the carboy, to see the difference, that may be best case scenario, but too much trouble for me to care about). The freezer will cycle on and off more often, leading to faster time to reach a steady state.

I however prefer reading the center temp in the carboy. The small fluctuations in temperature due to lag are not enough to bother me. I like constantly knowing the internal beer temp as opposed to the outside carboy wall temp.

$0.02.

Pangea

I have mine taped and covered to the outside of the fermenter. I don't sweat the temperature swings either way or method as I don't think it makes much of a difference. The beer is excellent, most who taste it want more of it and ultimately that is all that counts.

Catt22 said:

+10,000 I agree completely and I pretty much use the same method. My A419 probe is taped to the freezer wall at mid-keg level. The fermentation temperature is rock steady +/- 1 deg at most.

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This solved my problem too. My freezer is now right where I want it. Thanks everyone.

The idea in here to put the temp controller probe in the freezer rather than the thermowell makes sense. My question is how do you account for the significant temp increase inside the fermenter during active fermentation? I would guess you just have to keep a close eye on your thermowell readings for the first several days of fermentation and adjust accordingly?