[bluesman]

+1

Water has a heat capacity about 4 times that of air; this means that a given amount of water needs about 4 times as much heat to raise its temperature as that needed to raise the temperature of an equivalent amount of air. In other words, it’s much harder to change the temperature of a given amount of water than it is to change the temperature of the same amount of air.

Fluids have much better thermal conductivity because by their nature they are more dense than a gas. Due to the inherent heat capacity and thermal conductivity of water being higher and better, the compessor will work longer to reduce the temperature of the liquid but will cycle less due to increased heat capacity.

Monitoring the temperature of the beer using a thermocouple in a thermowell that is in direct contact with the beer would be the preferred method in an effort to potentially maximixe the life expectancy of the compressor.

[oscarvan]

I'm with Tim. I use two small freezers to ferment two buckets each. I have dual stage temp controllers with the probe in the air in the freezer. If I were to stick a 80º bucket in there and tape the probe to it the temp in the freezer would go to  minus 20º until the bucket reached 68º, running constantly and the mechanics getting pretty toasty in my 90º garage. Plus, the other bucket went in at, say 76º....so where does that end up when the thing finally shuts down?

Nope, everything nice and easy, probe in the air set at 66º and both buckets gently get there in about 8-12 hours, while the freezer mechanicals get to work, rest work, rest........

As far as the exothermal characteristics of fermentation, yes, that happens. So, I start at 66º and when the initial fermentation slows, I'll turn it up to 68º........

For completion's sake, the process is different in winter than summer. In winter I can get the wort down below 70º no problem and pitch right away. But in summer the barn is 90º after the burners run all day and I now place the yeast from the fridge in the fermenteezer to WARM to 66-68º and then the buckets, which I get down to about 80º with the chiller coil......then 8-10 hours later when all is equalized I pitch.....

[bluesman]

I'm with Tim. I use two small freezers to ferment two buckets each. I have dual stage temp controllers with the probe in the air in the freezer. If I were to stick a 80º bucket in there and tape the probe to it the temp in the freezer would go to  minus 20º until the bucket reached 68º, running constantly and the mechanics getting pretty toasty in my 90º garage. Plus, the other bucket went in at, say 76º....so where does that end up when the thing finally shuts down?

I hear you...but once the temp of the beer reaches setpoint, the freezer will shut off and won't come back on for an extended time, whereas keeping the probe in the air the compressor will cycle on and off much more, this will cause your freezer to work harder and reduce potentially reduce the life expectancy of the compressor.

[hopfenundmalz]

The starting transient is the hardest on the motor.

One should also consider the delta T around the setpoint on the controller.  I think I have mine at 2F to minimize the cycling a little.

The conical is in the big fridge called the garage in winter.  I add heat in that case.  No worries about cycling the motor (there is that pesky one year cycle).

[ccarlson]

I'm with Tim. I use two small freezers to ferment two buckets each. I have dual stage temp controllers with the probe in the air in the freezer. If I were to stick a 80º bucket in there and tape the probe to it the temp in the freezer would go to  minus 20º until the bucket reached 68º, running constantly and the mechanics getting pretty toasty in my 90º garage. Plus, the other bucket went in at, say 76º....so where does that end up when the thing finally shuts down?

I hear you...but once the temp of the beer reaches setpoint, the freezer will shut off and won't come back on for an extended time, whereas keeping the probe in the air the compressor will cycle on and off much more, this will cause your freezer to work harder and reduce potentially reduce the life expectancy of the compressor.

That's true, but it's also what is was designed to do.  If you put your temp probe in a deep thermowell you could likely freeze the outer layer of beer before the compressor cycled. Your best shot is to get your wort to the desired temperature before it ever goes into the fridge or freezer and then let the controlled ambient air keep it that way.

[bluesman]

I'm with Tim. I use two small freezers to ferment two buckets each. I have dual stage temp controllers with the probe in the air in the freezer. If I were to stick a 80º bucket in there and tape the probe to it the temp in the freezer would go to  minus 20º until the bucket reached 68º, running constantly and the mechanics getting pretty toasty in my 90º garage. Plus, the other bucket went in at, say 76º....so where does that end up when the thing finally shuts down?

I hear you...but once the temp of the beer reaches setpoint, the freezer will shut off and won't come back on for an extended time, whereas keeping the probe in the air the compressor will cycle on and off much more, this will cause your freezer to work harder and reduce potentially reduce the life expectancy of the compressor.

That's true, but it's also what is was designed to do.  If you put your temp probe in a deep thermowell you could likely freeze the outer layer of beer before the compressor cycled. Your best shot is to get your wort to the desired temperature before it ever goes into the fridge or freezer and then let the controlled ambient air keep it that way.

That's very possible.... but I chill my beer down near setpoint prior to loading in the keezer.

[ccarlson]

I was assuming that the wort was warm and you were using a thermowell. If you chill it first, either method will work well. In fact, the thermowell would probably work better in that case, although I've never tried.

[narvin]

I'm with Tim. I use two small freezers to ferment two buckets each. I have dual stage temp controllers with the probe in the air in the freezer. If I were to stick a 80º bucket in there and tape the probe to it the temp in the freezer would go to  minus 20º until the bucket reached 68º, running constantly and the mechanics getting pretty toasty in my 90º garage. Plus, the other bucket went in at, say 76º....so where does that end up when the thing finally shuts down?

Nope, everything nice and easy, probe in the air set at 66º and both buckets gently get there in about 8-12 hours, while the freezer mechanicals get to work, rest work, rest........

Freezers were not designed to cycle on and off repeatedly with the coolant never reaching its coldest temperature.  You want it to run continuously and then shut off for a while for the sake of its lifespan. If you're not going to measure the temperature of the wort, at least set the differential to 4 degrees, or put the probe in a small jug of water to avoid rapid cycling, as air temperature caused by convection currents changes quickly.

When I can't get my wort down to ferment temps and need to drop it 20 - 30 degrees before pitching, I find that the worst that happens is that I overshoot by about 5 or 6 degrees.  Setting the target temperature higher at first fixes this problem.  Another advantage is that with the freezer running constantly, I can get it down to pitching temps in about 4 hours.

[Tim McManus]

I agree that freezers were not designed to cycle on and off frequently.  They are designed more to keep the ambient temperature well below the freezing point and anything below that really doesn't matter.

However, a fridge is designed to keep the ambient temperature within a range, and their compressors are designed to handle frequent on-off cycles.  Think about how many times at 26 cu.ft. fridge's door is opened on a summer day with 5 kids running around.  However, this kind of activity is not common with a freezer.  You usually open that bad bear up once or twice a day and that's it, possibly less.

And about putting the beer in the fridge at the proper temperature, the same is true with food.  You never want to put a warm turkey into the fridge because it will warm everything up in the fridge.  It's best practice to let it cool to at least room temperature and then put it in the fridge.  Additionally, it's just better to pitch at fermentation temperature anyway, so the only heating you'll get is from yeast metabolism, which will be slight and manageable with a good regulator.

[micsager]

Interesting discussion here.  I guess as with many things, we all have our own opinions, and do things our own way.  And as most of us don't have glycol chillers, we have to modify equipment to meet our needs. 

I'm sticking with taping the probe to the side of one buckets with some insulation.  It has served me well for about 5 years.
I do always get my wort to fermentation temp priot to putting in the freezer, so maybe that has helped me.  Who knows?

[weithman5]

I with 5 kids running around.    You never want to put a warm turkey into the fridge because it will warm everything up in the fridge. lator.

how the hell do you have warm turkey left with 5 kids running around.?

[weithman5]

although i am in the process of building a fermentation chamber and all i brew have been lagers right from the start.  i have used a large styrofoam cooler (we get frozen vaccines in them) and this holds my fermenters. (usually 1 or two 1 gallons) (why i am building a bigger one). i use the foam/gel packs frozen and keep them in the cooler with the fermenter and this has kept temperature down easily.  in the winter i warm it up with an 8 watt christmas light. 

[ccarlson]

Just leave the turkey out on the counter for a few days and snack on it until it's gone.

[Tim McManus]

Interesting discussion here.  I guess as with many things, we all have our own opinions, and do things our own way.  And as most of us don't have glycol chillers, we have to modify equipment to meet our needs. 

I'm sticking with taping the probe to the side of one buckets with some insulation.  It has served me well for about 5 years.
I do always get my wort to fermentation temp priot to putting in the freezer, so maybe that has helped me.  Who knows?

I too am enjoying the discussion.  It's broadened my understanding of some the different uses and techniques folks use.  If it works for you and it makes great beer, who I am to say you're doin' it wrong? 

[micsager]

Interesting discussion here.  I guess as with many things, we all have our own opinions, and do things our own way.  And as most of us don't have glycol chillers, we have to modify equipment to meet our needs. 

I'm sticking with taping the probe to the side of one buckets with some insulation.  It has served me well for about 5 years.
I do always get my wort to fermentation temp priot to putting in the freezer, so maybe that has helped me.  Who knows?

I too am enjoying the discussion.  It's broadened my understanding of some the different uses and techniques folks use.  If it works for you and it makes great beer, who I am to say you're doin' it wrong? 

"great beer"  Well sometimes.  How 'bout we just say "good beer"