keezer temp probe?

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brewQC

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Over the weekend I finally 'finished' my keezer. It only seems to keep the temperature between the setpoint and differential of the temp controller for about 10 minutes, then it cycles back on. Is the temp probe supposed to be submersed in water or dangling in air? It seems like you'd want it to not read just the air temp since that would change faster.

I have a johnson digital temp controller with the probe taped to a water bottle on the compressor 'hump' with the setpoint at 40, 3 degree differential and a 8 minute anti-short cycle delay.

Taking suggestions from threads about this I already insulated the collar with 3/4 blue foam insulation, and have a computer fan mounted to some L-brackets drilled into the collar. The wood collar is a little cooler than the freezer body, the lid is by far the coldest outside part.
 
Hi

Try taping it to the wall of the freezer about half way between the top and bottom of the wall. Bump the differential up to about 8 degrees. You indeed do not want it hanging in air. A "large" differential on the wall still means a small differential in the keg since the keg averages out the temperature swings.

If it's a small freezer, the freezer is empty, and the room is warm, it will cycle a bit. Even more so if one of more sides has poor airflow.

Bob
 
Hi, Thanks for the reply! I'll try that out tonight when I can sit around and monitor the temp/times. What would be a good amount of running time vs not-running time?
 
i have found the best results for me was taping it to the side of one of my kegs. The large volume of the kegs doesnt fluctuate like the air temp, and besides its measuring the temp of the beer which is what i want to control anyway.
 
I would recommend attaching the probe to one of the kegs under some insulation. Monitoring the temperature using an item with a large thermal mass is the best way to control the temperatures. It helps even out fluctuations caused by door opening and temperature stratification. And isn't it the beer temperature that we're trying to control in the first place?

I would think attaching the probe to the freezer wall would result in very short cooling cycles if directly adjacent to a cooling coil. Using the temperature differential to then average out the beer temperature, while it may work, seems like a round-about way of temperature control when a more direct method can be used.
 
Hi

The idea is to control the temperature *before* it hts your beer. The keg will indeed average the temperature out, but that's not what you want in a controller. You want the control loop to respond quickly to changes and to "control" them out. Put another way, you don't want the beer to change temperature at all.

If you put the probe about half way down the wall, you are well away from any cooling coils on normal freezers. The cycle rate is actualy a bit slower than the originaly designed cycle rate on the freezer.

Bob
 
....The idea is to control the temperature *before* it h(i)ts your beer.....
This might be YOUR idea but it certainly is not THE idea, based on the majority of posts I have read on this forum.

To control the temperature of the beer, which IS our ultimate goal, one can use an indirect or direct method. While boths methods can work, the majority of posts here seem to recommend a direct method. A direct method is generally simpler, consistent, and safer.

That being said, many commercial coolers use an indirect method of temperature control of their contents. My stock TRUE GDM-12 corny cooler uses an indirect method but with a well engineered process. Probe placement is fixed and thermostat cut-in and cut-out is fixed to a specific range. It is designed as a refrigerator with alternating cooling/defrost cycles and works very well.
 
This might be YOUR idea but it certainly is not THE idea, based on the majority of posts I have read on this forum.

To control the temperature of the beer, which IS our ultimate goal, one can use an indirect or direct method. While boths methods can work, the majority of posts here seem to recommend a direct method. A direct method is generally simpler, consistent, and safer.

That being said, many commercial coolers use an indirect method of temperature control of their contents. My stock TRUE GDM-12 corny cooler uses an indirect method but with a well engineered process. Probe placement is fixed and thermostat cut-in and cut-out is fixed to a specific range. It is designed as a refrigerator with alternating cooling/defrost cycles and works very well.

Hi

If you tape the probe to a keg, and then swap around kegs, your controll point is going to change every time you do anything. Regardless of where the controll point is, you *will* need to calibrate things. That calibration will only be valid for a single control location. Why do it the hard way? There is 100+ years of engineering experiance out there on how to do this...

Bob
 
Hi

Try taping it to the wall of the freezer about half way between the top and bottom of the wall. Bump the differential up to about 8 degrees. You indeed do not want it hanging in air. A "large" differential on the wall still means a small differential in the keg since the keg averages out the temperature swings.

If it's a small freezer, the freezer is empty, and the room is warm, it will cycle a bit. Even more so if one of more sides has poor airflow.

Bob

Are you really recommending this approach, again?
Putting the probe on a chest freezer wall, or recommending it, is idiotic.
All freezers are different, and which wall chills first is different- and it complicates things because you aren't monitoring what you are trying to keep cold: the beer.

Put the probe underneath some insulation on whatever is the smallest thermal mass you are going to have in the keezer- a bottle or a keg. This will prevent freezing of small things. For kegs, a gallon jug is a good enough if you don't want to deal with swapping the probe between kegs.
 
Hi

The idea is to control the temperature *before* it hts your beer. The keg will indeed average the temperature out, but that's not what you want in a controller. You want the control loop to respond quickly to changes and to "control" them out. Put another way, you don't want the beer to change temperature at all.

If you put the probe about half way down the wall, you are well away from any cooling coils on normal freezers. The cycle rate is actualy a bit slower than the originaly designed cycle rate on the freezer.

Bob
The idea is to not have to monkey around finding out where the cooling coils are so you don't tape near one or where the ones that get cold first are. Also, not to have to spend days figuring out what magical temp and differential setting will keep you beer at the actual temp you want.
Just put the probe on the actual beer, or some facsimile, then insulate over the probe.

The differential on most controllers is adjustable down to .5F. That is more than sufficient.

Your 'control loop' doesn't even include the beer temp, unless you count yourself constantly monitoring the beer to determine how much to adjust the controller temp or differential of the cooling coils to get the beer temp you want.

Most people buy a controller to do the controlling, and don't want to put out a bunch of effort to maintain temps, which is why they bought a controller.
 
Hi

If you tape the probe to a keg, and then swap around kegs, your controll point is going to change every time you do anything. Regardless of where the controll point is, you *will* need to calibrate things. That calibration will only be valid for a single control location. Why do it the hard way? There is 100+ years of engineering experiance out there on how to do this...

Bob
If you tape the probe to the freezer wall, you will need to adjust the controller temperature every time the ambient temp outside the keezer changes.

There is no re-calibration needed if switching between 1 keg and another, because it is a direct indicator. This is exactly why it is the preferred method, along with numerous other benefits. In this case, the 'control location' never changes, and is irrelevant anyway, because we are using a direct indicator regardless of where the beer is positioned.

Your approach isn't even using a secondary indicator for feedback, it is using the primary input (cold freon) as the indicator.

I don't know what control theory you are using, but I have never heard of one that favors staying as far removed as possible from the primary indicator (the beer). Even worse, one that uses the primary input (cold freon in this case) as a secondary indicator.

And I understand your position that the beer acts as an integrator, which makes it possible to control the temp more tightly using a secondary indicator. I also understand that would involve much more tuning and dependence on ambient conditions, something which you repeatedly/conveniently leave out, and neither of which the average person on these forums has either the desire to do, knowledge of, or control over. They want the simplest and most suitable solution.

Using your logic and theory, using a small bottle will give the same results as your approach, without having to worry about cooling coil location and without needing any temp offsets- just adjusting the differential for acceptable cycling freq.

RE:control loop reacting fast- We don't want the control loop acting fast for compressor based systems. This is exactly why everyone (else) recommends putting the probe on something massive, setting a small differential (~1F) and the desired temp (~38F), then calling it good; while you, confusingly, recommend setting an abnormally high differential (8F) with the probe on some object whose temp is far removed from the beer temp, then go about searching for what temp to set on the controller to get the beer temp you want.

Does that about sum it up?

Maybe you and Cat22 should battle it out over 'probe in air' (even for fermenting according to him) and 'probe on cooling coil'. The common element to both of your arguments is the insertion of another controller (yourself) into the loop- Cat22 with himself adjusting the control temp offest multiple times a day/week during ferment, and you fiddling about trying to determine the proper temp offset and differential because you are using the primary input as the indicator.
 
Hi
There is 100+ years of engineering experiance out there on how to do this...

Bob
The engineering that has been going into appliances for 100+ years is to figure out how to save $.02 while still getting 'acceptable performance', and making it past the warranty period. When building a keezer or ferm chamber, using appliance engineering tactics is not a good course to follow. Flat out copying them is even worse.
 
I submerse my probe in water. Get a 20-30 minute cycle every 4-6 hours. I have mine set at 3 celcius with a 3 degree differential. Works flawlessly
 
I submerse my probe in water. Get a 20-30 minute cycle every 4-6 hours. I have mine set at 3 celcius with a 3 degree differential. Works flawlessly

I think some guys have had their probes get water damage even though they are 'waterproof'. Some use gel, or a thermowell of some sort to avoid this.

You could probably tighten your temp diff without too much extra cycling. If your current probe vessel is smaller than your smallest bottle/keg, you might be able to reduce cycling and/or reduce temp swings by putting the probe on/in a larger vessel.

Interestingly, for fermenting, strapping/taping the probe to the outside of the vessel, then insulating over it, works better than a thermowell in the middle of the vessel. This allows some influence of the chamber air on the probe to control overshoot as well as reduce cycling freq and help minimize the effects of short term air temp spikes (lid openings, new warm keg). It also prevents radial temp stratification in the vessel at late ferm stages caused by using a thermowell.
 
If you tape the probe to the freezer wall, you will need to adjust the controller temperature every time the ambient temp outside the keezer changes.

There is no re-calibration needed if switching between 1 keg and another, because it is a direct indicator. This is exactly why it is the preferred method, along with numerous other benefits. In this case, the 'control location' never changes, and is irrelevant anyway, because we are using a direct indicator regardless of where the beer is positioned.

Your approach isn't even using a secondary indicator for feedback, it is using the primary input (cold freon) as the indicator.

I don't know what control theory you are using, but I have never heard of one that favors staying as far removed as possible from the primary indicator (the beer). Even worse, one that uses the primary input (cold freon in this case) as a secondary indicator.

And I understand your position that the beer acts as an integrator, which makes it possible to control the temp more tightly using a secondary indicator. I also understand that would involve much more tuning and dependence on ambient conditions, something which you repeatedly/conveniently leave out, and neither of which the average person on these forums has neither the desire, knowledge, or control over. They want the simplest and most suitable solution.

Using your logic and theory, using a small bottle will give the same results as your approach, without having to worry about cooling coil location and without needing any temp offsets- just adjusting the differential for acceptable cycling freq.

RE:control loop reacting fast- We don't want the control loop acting fast for compressor based systems. This is exactly why everyone (else) recommends putting the probe on something massive, setting a small differential (~1F) and the desired temp (~38F), then calling it good; while you, confusingly, recommend setting an abnormally high differential (8F) with the probe on some object whose temp is far removed from the beer temp, then go about searching for what temp to set on the controller to get the beer temp you want.

Does that about sum it up?

Maybe you and Cat22 should battle it out over 'probe in air' (even for fermenting according to him) and 'probe on cooling coil'. The common element to both of your arguments is the insertion of another controller (yourself) into the loop- Cat22 with himself adjusting the control temp offest multiple times a day/week during ferment, and you fiddling about trying to determine the proper temp offset and differential because you are using the primary input as the indicator.

Hi

There are a few things that are pretty obvious here:

1) You don't do this for a living, and you are not an engineer. Indeed I am an engineer and I do this for a living. What you know is from reading threads and guessing at stuff.

2) For what ever reason, you have a really big issue with accepting that there are multiple valid ways to do this, each with their plusses and minuses.

3) There is absolutely no way you will ever listen to anything but your own ideas. You have made that abundantly and violently clear.

Bob
 
fwiw, I'm also an engineer, been one since 1973, practicing multiple disciplines, and I think taping a temperature probe to a freezer wall is pretty much the opposite of a sound way to keep beer at any specific temperature.

Whether carboy or keg, I strap the probes on my Ranco controllers directly to the middle covered with a chunk of 1" thick closed cell foam insulation, set the desired beer temperature, dial in a degree or two of differential, then let everything work...perfectly. If I want raise or lower the beer temp I can do it at will and the controller will hit it on the nose and keep it within the differential. No short cycling, ever...

Cheers!
 
Hi

There are a few things that are pretty obvious here:

1) You don't do this for a living, and you are not an engineer. Indeed I am an engineer and I do this for a living. What you know is from reading threads and guessing at stuff.

2) For what ever reason, you have a really big issue with accepting that there are multiple valid ways to do this, each with their plusses and minuses.

3) There is absolutely no way you will ever listen to anything but your own ideas. You have made that abundantly and violently clear.

Bob

Indeed it seems pretty obvious that you are not very good at seeing the obvious. You also seem to be describing yourself, since I have already admitted that with enough tuning, your way can produce tighter control, it just isn't feasible.
You also conveniently and repeatedly leave out about 99% of the work involved in your approach.

Algorithm for your "probe on wall" approach:
(with some old school GOTOs in there just for fun)
Code:
IF you don't already know where it is.
   Find where the last place is that the cold freon reaches on the inner 
   wall of the freezer.
   Tape the probe as far away from that spot and next closest freon 
   line as possible.
Set the controller temperature to some magical offset number 'a bit', 
scientifically speaking, colder (or maybe warmer, who knows) than you want 
your keg.(Warning this temp setpoint + offset may change over time for a variety 
of reasons due to this approach) 
Set the differential to a magical number that will control cycling freq. 
(Warning this differential may change over time for a variety of reasons 
due to this approach)
IF your controller doesn't have ASD.
   Go to the store and buy a new freezer because your compressor is fried 
   due to a hot start condition.
IF you don't have an extra temperature monitor.
   Buy a temperature monitor to see what your actual beer temp is as a result
   of the secondary temperature setting on the controller.
Monitor your beer temp repeatedly waiting for it to stabilize.
(Should only take a week or so.)
IF it isn't at the temp you want
   adjust the offset
   GOTO: previous step
If your cycling frequency isn't acceptable
   increase the differential
   GOTO: step 1
IF the ambient temp external to the chamber changes
   GOTO: step 1
Algorithm for the direct indicator 'probe on vessel' approach:
Improved with a hard coded relative offset GOTO- for her pleasure.
Code:
Tape/strap the probe to a keg of beer, or some facsimile, then insulate.
Set the temp of the controller to exactly the temp you want your beer.
Set the differential to exactly your temp tolerance level (down to ~.5F).
Wait one day.
Drink your perfect temperature beer.
IF your cycling freq is too high.
   Use a larger facsimile, add a fan, or more insulation over the probe,
   or give up some temp tolerance in favor of compressor life.
   GOTO 3 steps previous
 
Whether carboy or keg, I strap the probes on my Ranco controllers directly to the middle covered with a chunk of 1" thick closed cell foam insulation, set the desired beer temperature, dial in a degree or two of differential, then let everything work...perfectly.
This approach is mandatory for Ranco's, at least all the ones I have seen in use for homebrewing (the ones sold at LHBS), since they do NOT have any ASD.
 
Sounds like some of our brew brothers need a beer. Try what sounds logical to you and see what works. What works well for me is a 20oz water bottle with the probe (wrapped in a plastic bag to prevent corrosion) submersed, stuck through a hole drilled in the cap. The bottle sits on the hump.
 
Your 'probe on wall' approach is no different than using a smaller facsimile of a keg of beer. The difference is that using your method, you have to account for the severe impact of the freon influence in the control loop. Finding the location of the loops in order to avoid them is the easy part, getting all of the offsets and differential correct is the hard part.

Using a small bottle, with the probe on or in it, is essentialy your same set up, with the severity of the freon impact mitigated. The smaller bottle, as well as the insulation if the probe is taped to the side, serve to both cut on early and cut off early, which is what you tout as the benefit of your approach.

Additionally, taping the probe to the wall also increases the effect of external ambient temps on the control system. The 'probe on bottle/facsimile' has a bit of this as well, but the severity of the impact is reduced, and more importantly, no adjustment is needed since there is no offset of the temp setpoint from the desired beer temp (as long as a reasonable facsimile is used).
 
Hi

3) There is absolutely no way you will ever listen to anything but your own ideas. You have made that abundantly and violently clear.

Bob

Did you mean to say 'vehemently'? I would agree with that.

If you indeed meant 'violently', here is an appropriate cinematic reference- "Because I was afraid of worms, Roxanne! Worms!"
 
I'm very interested in this thread since we will be purchasing a 7.0 chest freezer and Ranco Temp Controller. I initially thought that I would immerse the temperature probe into a small bottle of propylene glycol. Please be aware:Neither the Ranco ETC or Johnson A419 probes are recommended for direct submersion in any liquid. The manufacturer recommends use of a thermal or bulb well.. Now I'm wondering if taping the probe to a fermenter or keg and insulating it would be the better way to go.
 
Hi

The idea is to control the temperature *before* it hts your beer. The keg will indeed average the temperature out, but that's not what you want in a controller. You want the control loop to respond quickly to changes and to "control" them out. Put another way, you don't want the beer to change temperature at all.

If you put the probe about half way down the wall, you are well away from any cooling coils on normal freezers. The cycle rate is actualy a bit slower than the originaly designed cycle rate on the freezer.

Bob

Bob, the wall is not what's cooling the beer though. The ambient air is what cools the beer. Therefore, gauging temp based off the wall temp is not an accurate or reliable method. I'm not saying it won't get the job done, but it's not going to be as efficient as taping the probe to a keg.

By having a probe directly on the keg, it measures the temp of the beer inside pretty darn accurately, and changes the ambient temp (by turning on compressor) only when needed.


That being said, there's different ways to do it. I personally don't care enough to affix the probe to a keg each time, so I have it hanging down about halfway, just suspended in mid air (not touching anything). I set my Setpoint to 40F, and my diF to 5 degrees, with a 12 minute anti-short delay. With that method, mine typically cycles on every 20 mins or so, which seems about right (depends on how many kegs with how much beer left in them).
 
I'm very interested in this thread since we will be purchasing a 7.0 chest freezer and Ranco Temp Controller. I initially thought that I would immerse the temperature probe into a small bottle of propylene glycol. Please be aware:Neither the Ranco ETC or Johnson A419 probes are recommended for direct submersion in any liquid. The manufacturer recommends use of a thermal or bulb well.. Now I'm wondering if taping the probe to a fermenter or keg and insulating it would be the better way to go.

Depends on the application. For a ferm chamber, I'd suggest taping the probe to the wall of the fermenter containing the most recently brewed beer, and then securing some sort of insulating material on top of the probe (rag, folded up paper towel, scrap of foam, etc. For a kegerator or keezer, I'd suggest taping the probe to a small bottle full of water.

I would not recommend taping the probe to the chamber wall.
 
I personally don't care enough to affix the probe to a keg each time, so I have it hanging down about halfway, just suspended in mid air (not touching anything). I set my Setpoint to 40F, and my diF to 5 degrees, with a 12 minute anti-short delay. With that method, mine typically cycles on every 20 mins or so, which seems about right (depends on how many kegs with how much beer left in them).

Your compressor will last you a lot longer if you secure the probe to something with a little thermal mass. There's no need to mess with the probe every time you change kegs out. I taped my sensor to a small bottle of water that sits out of the way on the compressor hump in the corner. I have a smaller differential that you, and my keezer only kicks on a few times a day when it's full.
 
Depends on the application. For a ferm chamber, I'd suggest taping the probe to the wall of the fermenter containing the most recently brewed beer, and then securing some sort of insulating material on top of the probe (rag, folded up paper towel, scrap of foam, etc. For a kegerator or keezer, I'd suggest taping the probe to a small bottle full of water.

I would not recommend taping the probe to the chamber wall.

Thanks. This freezer will be used for fermenting & lagering (of course at different times) and I have a separate dual tap kegerator for dispensing.
 
I'm very interested in this thread since we will be purchasing a 7.0 chest freezer and Ranco Temp Controller.
The Ranco controller, at least the one commonly sold for homebrew use, does NOT have Anti Short cycle protection. If you want a prebuilt unit, the Johnson digital controller is a better choice. If you want to save some money and don't mind some DIY, look into the thead about the $25 dual stage ebay aquarium controllers. It is a good choice for a ferm chamber left in the garage since it heats or cools automatically with no manual mode changes.
 
Is this thread for real. Literally the easiest thing about brewing is cooling beer. Do what you want, dangle it, tape it to the keezer, tape it to the keg. Choose which way you like best. **** it's not rocket science.

Personally I dangle :)
 
Is this thread for real. Literally the easiest thing about brewing is cooling beer. Do what you want, dangle it, tape it to the keezer, tape it to the keg. Choose which way you like best. **** it's not rocket science.

Personally I dangle :)
This whole forum can't be for real can it? Literally, the easiest thing about beer is making it. Quit over-complicating things with things like different special grain combinations, yeast strains, hop varieties, temperature control, etc. It is almost as crazy as all this fanaticism with sanitation- we are trying to make things fester for ****s sake. You put some grain in a pot, dip something dirty in it, let it fester, and you get beer.

Personally I dangle in it.
 
cwi said:
This whole forum can't be for real can it? Literally, the easiest thing about beer is making it. Quit over-complicating things with things like different special grain combinations, yeast strains, hop varieties, temperature control, etc. It is almost as crazy as all this fanaticism with sanitation- we are trying to make things fester for ****s sake. You put some grain in a pot, dip something dirty in it, let it fester, and you get beer.

Personally I dangle in it.

Ha!

On a serious note though, there have been a few threads over the last few years where people fried the compressors in brand new freezers because they ran them empty with the probe dangling and no ASD. Hate to see someone kill a perfectly good freezer because they got bad advice on here.
 
I was referring to two people arguing about whether to tape it to a keg or taping it to the wall. I agree the topic is worthwhile, but not worth two pages of arguing. Sorry that wasn't clear in my sarcastic post.
 
The Ranco controller, at least the one commonly sold for homebrew use, does NOT have Anti Short cycle protection. If you want a prebuilt unit, the Johnson digital controller is a better choice. If you want to save some money and don't mind some DIY, look into the thead about the $25 dual stage ebay aquarium controllers. It is a good choice for a ferm chamber left in the garage since it heats or cools automatically with no manual mode changes.
Oh well, Ranco is being delivered today. Did not get the pre-wired one. From what I've read, if you set the differential properly, and correctly mount the probe, you won't have an issue with short cycles. Freezer is going in the basement.
 
I was referring to two people arguing about whether to tape it to a keg or taping it to the wall. I agree the topic is worthwhile, but not worth two pages of arguing. Sorry that wasn't clear in my sarcastic post.
The two pages of arguing were caused by people (actually just one person before your entry) who inject their opinion that there is no difference among placements, or even worse, that 'probe on wall' or 'probe in air' is the best method.

If there was sarcasm in your post, it was non-obvious. Congratulations for keeping the argument going.
 
Oh well, Ranco is being delivered today. Did not get the pre-wired one. From what I've read, if you set the differential properly, and correctly mount the probe, you won't have an issue with short cycles. Freezer is going in the basement.

Basement or garage, if the external ambient temps will rise both above and below the ferm temp during a ferment (like in a garage), or even be stable at more than ~1F below ferment temp (like in a basement), a dual stage controller is beneficial since both heat and cool will be needed in both cases.

RE: short cycling- There are ways to compensate for not having built in ASD, but why bother when they will never guarantee protection, and generally degrade temp control. Especially when a cheaper ($25) dual stage controller with ASD is available.

Personally, I would return the Ranco and get the ebay controller, a fancier Love dual stage, or the Johnson digital. I don't know why the standard Rancos continue to be mentioned as a viable choice. Same goes for the inline pumps when the same exact pump in a center inlet design is superior for virtually all homebrew applications.
 
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