[James K]

One advantage of a freezer over a fridge is that, with the door on top, all the cold air doesn't spill out when you open it.  When my fridge (fermentation chamber) is opened, yeah, it kicks on.  Freezers (lagering and keezer), no.  Anyway, how often are you going to open it?  The difference in how much work your compressor does should be negligible.  Also, the jar of water isn't a real analog for the beer for those using the freezer (or fridge) as a fermentation chamber, as it isn't generating heat like the ferment.  Just another consideration.

I think if I had the probe in water, I'd want zero "swing" set into the system, because by the time the probe registered a change,  the beer would already have changed temperature.  A few degrees swing in air temperature, and the beer will stay steady.

Right now I never open the freezer, I’m in the process of making a keezer out of it and I’ve just been keeping bottles cold and I’m cold crashing a beer in there. Perhaps I should take my fridge temp probe out of the water, but I don’t really open the door on that unless I’m changing a keg or fiddling with one.

I could see where the probe in the air has its benefits over than being in water.  My fridge is kinda clunky though and I’ve always tried to keep the probe as far away from the visible coils as possible.

That’s kinda why I wanted to get the keezer going (once i get all the material) I think it would be more efficient than the junk fridge I got over a year ago. (It came with a tap, empty keg shell i turned into a keggel, the temp controller, a sanke and co2 tank, $150!)

Thanks for discussion.

[denny]

Quite likely.

Here's how I learned. When I got my first freezer, before ever using it for beer, I put a keg of water in it for a couple of weeks, with a thermometer in the keg.  Tried a bunch of arrangements.  With the freezer at its warmest setting and a +2°/-2° swing on the controller, the water held steady at the set temp.  But with the freezer set colder, it would get so cold in the chamber when the freezer kicked on, the controller couldn't react quickly enough, and the water would plunge toward freezing.   You might want to try a similar experiment to find the best setup on your own equipment.

(BTW my probe is in the air, not water, and the liquid in the keg still holds steady.  Remember,  liquid will change temperature much more slowly than air, as it has much greater thermal mass.)

Yeah, I can see those kind of swings with the probe in air.  I tape mine to the side of the fermenter.  Between that and the features of my Auber controller, I get very stable temps.

[denny]

(BTW my probe is in the air, not water, and the liquid in the keg still holds steady.  Remember,  liquid will change temperature much more slowly than air, as it has much greater thermal mass.)

I get what you’re saying, and, I guess I’m wondering what is better, a shorter or longer wave length of oscillating temperature?

If the probe is in the air and you open the keezer (as I would be doing) the unit would kick on to adjust he temp faster than if he probe was in water. But if the probe is in water, the unit should not kick on as often.
Thoughts?

You don't want the probe either in air or water, unless those are the temps you care about.  You want it attached to the fermenter.

[Robert]

If we're talking about a keezer, holding ambient steady is all that matters. There's no differential.  And I still prefer that approach with fermentation.  As long as ambient is all you can affect with heating and cooling, that is, you don't have a jacketed fermenter, I find that when putting the probe in a thermowell or on the fermenter, you will inevitably end up with the ferment itself having temperature swings:  It will have already warmed up above set temp before the controller kicks on, and then it will overcorrect, as it will keep cooling running till the liquid hits set temp, when ambient will be much lower, and the liquid will then continue cooling, and your heat will kick on, and here we go again.... I just control ambient, and from experience I know what the differential between that and the ferment will be.  (I monitor the ferment with a separate probe in the thermowell.)   This works for me, but everybody will figure out what works best for themselves.  It all depends on your particular equipment, and, I'll add, your desired degree of precision and willingness to take a hands-on approach.

[denny]

If we're talking about a keezer, holding ambient steady is all that matters. There's no differential.  And I still prefer that approach with fermentation.  As long as ambient is all you can affect with heating and cooling, that is, you don't have a jacketed fermenter, I find that when putting the probe in a thermowell or on the fermenter, you will inevitably end up with the ferment itself having temperature swings:  It will have already warmed up above set temp before the controller kicks on, and then it will overcorrect, as it will keep cooling running till the liquid hits set temp, when ambient will be much lower, and the liquid will then continue cooling, and your heat will kick on, and here we go again.... I just control ambient, and from experience I know what the differential between that and the ferment will be.  (I monitor the ferment with a separate probe in the thermowell.)   This works for me, but everybody will figure out what works best for themselves.  It all depends on your particular equipment, and, I'll add, your desired degree of precision and willingness to take a hands-on approach.

I can't figure out why we have such different experiences with this.  Again, maybe it comes down toe specific equipment, but my temps are rock steady.  I _may_ see a .5-1F swing but never any more than that.

[Robert]

Okay, I'm game to try the probe in my thermowell next batch, Denny.  Maybe things will have changed for me.  I did get a new controller recently.  To get your steady temps, how tight do you set your +/- differential? I'll give it a try.

EDIT actually, my minimum differential is 1°F, so I'll try it.  And I'll eat crow right here if appropriate -- and I really hope it is.

[denny]

Okay, I'm game to try the probe in my thermowell next batch, Denny.  Maybe things will have changed for me.  I did get a new controller recently.  To get your steady temps, how tight do you set your +/- differential? I'll give it a try.

EDIT actually, my minimum differential is 1°F, so I'll try it.  And I'll eat crow right here if appropriate -- and I really hope it is.

Right now, I'm lagering a G pils.  Cooling set point is 36, heating set point is 34.  The controller also has a function to set the restart time so the freezer doesn't come on too soon after the last time.

[James K]

(BTW my probe is in the air, not water, and the liquid in the keg still holds steady.  Remember,  liquid will change temperature much more slowly than air, as it has much greater thermal mass.)

I get what you’re saying, and, I guess I’m wondering what is better, a shorter or longer wave length of oscillating temperature?

If the probe is in the air and you open the keezer (as I would be doing) the unit would kick on to adjust he temp faster than if he probe was in water. But if the probe is in water, the unit should not kick on as often.
Thoughts?

You don't want the probe either in air or water, unless those are the temps you care about.  You want it attached to the fermenter.

I have never really used my temp controller for cold fermentation, just for setting the temps on my fridge and freezer. I use the controllers for my fridge and freezer so I know those units are set around 38*, serving temperature. When I use my digital controller for heat while fermenting I use a thermowell with a wrap and I put the carboy in a hoodie. I set a 1* dif because I’m not battling heat and cooling at the same time. The wrap turns on if it gets too cold it shuts off so i have a total 2* swing. +/- 1/10s of a few degrees.

Right now I have a 2*+/- dif set on my digital controller (freezer, which doesn’t have much going on in her right now), my analog controller (fridge) doesn’t give me an option and I’m not sure what it’s differential is set to? That’s why I’ve placed the analog probe in water. If a liquid temp is around 38* my kegs are also around 38*.

Do either of you know about analog controllers and how many degrees they might allow before trying to re adjust?

In the past my fridge would develop frost, then get warm to where I would have puddles in the kegerator. I think for my fridge and the analog controller placing the probe in water has been helpful.

[Robert]

According to the instructions (I hang on to these things!) the Johnson Controls/Penn analog units (if that's what you have)  will cool to 4°F below  set temperature and then kick on again when temperature rises to set point.  Therefore, they instruct you to keep the probe in the air, not in liquid or attached to the fermenter.   They rely on the steadying thermal mass of the liquid to keep it at set temperature.  Anyway I still use them for my lagering freezer and my keezer (probe in the air) and the beer stays quite steady at the set temperature.

[James K]

According to the instructions (I hang on to these things!) the Johnson Controls/Penn analog units (if that's what you have)  will cool to 4°F below  set temperature and then kick on again when temperature rises to set point.  Therefore, they instruct you to keep the probe in the air, not in liquid or attached to the fermenter.   They rely on the steadying thermal mass of the liquid to keep it at set temperature.  Anyway I still use them for my lagering freezer and my keezer (probe in the air) and the beer stays quite steady at the set temperature.

Cool, thanks. I got mine used and it didn’t come with instructions. I have a Johnson controller, but that explains why my fridge has dipped into the freezing temp range and produced frost when set above freezing by a few degrees.

I’m gonna have to,try the air and see what happens. Whoever build the original kegerator I bought used didn’t really build it with the best design thought process. That’s kinda why I’ve been doing what I’ve been doing, because it’s been a pain to get the probe in an area that’s not right next to the coils, so i placed it in water thinking it would give me a more steady reading.

[Estaban]

Looks like I found a 5 cu. ft. chest freezer that I'll be hooking to the Inkbird2 control based on the suggestion. I appreciate all the discussion on this topic. Like I said I need something I can set and forget for the couple weeks of fermentation and racking into secondary at points. I'll get more detailed once my life stables out and I find more time to look at number more in depth.

[James K]

Looks like I found a 5 cu. ft. chest freezer that I'll be hooking to the Inkbird2 control based on the suggestion. I appreciate all the discussion on this topic. Like I said I need something I can set and forget for the couple weeks of fermentation and racking into secondary at points. I'll get more detailed once my life stables out and I find more time to look at number more in depth.

That should be good. I feel like if you wanted to build a collar you could fit two carboys in your new chest freezer. Here’s a picture of my 7cuft. I have a beer fermenting now but could easily move it to the other side and open up room for the shelf if I wanted two carboys in here. A solid 6” collar would be fairly easy to make (would only cost about $10). I’m working on one for taps to turn mine into a new kegerator.

After reading this post and what not I’ve adjusted my freezer a bit and I my temp is fairly steady. THe probe is in the termowell though.

Good luck.

[Robert]

Okay, I'm game to try the probe in my thermowell next batch, Denny. Maybe things will have changed for me.  I did get a new controller recently.  To get your steady temps, how tight do you set your +/- differential? I'll give it a try.

EDIT actually, my minimum differential is 1°F, so I'll try it.  And I'll eat crow right here if appropriate -- and I really hope it is.

Well, this just won't work for me.  Way too much strain on the fridge without the desired control of the ferment temperature.   Had to switch back to my regular system of probe controlling ambient while watching ferment temperature in the thermowell.   Tried and true.  Don't know why we get different results, maybe my using a full size fridge (really full size, no freezer compartment) is a big part of it.  Gave it a try.  Just as well this way, not sure if you can shoot and eat crows in Ohio.   

[denny]

Well, this just won't work for me.  Way too much strain on the fridge without the desired control of the ferment temperature.   Had to switch back to my regular system of probe controlling ambient while watching ferment temperature in the thermowell.   Tried and true.  Don't know why we get different results, maybe my using a full size fridge (really full size, no freezer compartment) is a big part of it.  Gave it a try.  Just as well this way, not sure if you can shoot and eat crows in Ohio.   

Thanks for report ans I appreciate your willingness to try!  I ferment in a 15 cu. ft. chest freezer with an Auber TD100 controller.  Undoubtedly the equipment is why we get different results.

[Robert]

^^^^
The set-it-and-forget-it approach would have been nice.  When this fridge eventually dies, I'll sure have a better idea of what to replace it with.