Heads Up on Crash Cooling

[Sudz]

I just discovered something on crash cooling which may be of interest to the forum... It also may be obvious to everyone but me.

I have a freezer which I modified to use for crash chilling brews and wine I make. It works well and I typically strap the thermocouple to my carboy for measuring the temp at the bottle rather than the air temp of the freezer. This was actually recommended by someone as the best way to know the brew temp since the freezer temp tends to fluctuate with the freezer cycling.

The mass of the carboy and liquid change slowly which eliminates the more rapid cycling of the freezer when compared to measuring the air temp for control.

This has worked well for things I don't drop to far. However, I recently set up to crash cool 6 gal of wine to precipitate out the tartaric acid. You take the temp down to about 28 degrees F to do this.

I strapped my thermocouple to the carboy as usual. Here's what happened.

The freezer came on and ran over night as expected to drop the temp. However, since the mass of the carboy changes temp very slowly, my freezer maxed out at about 6 degrees F and sit there while the carboy cooled to my 28 degrees. Eventually the carboy reached the 28 and the cooling cycled off... but the freezer is at 6 degrees. It stays at 6 degrees since it's a good freezer and everything has been saturated at this temp. Now the carboy continues to chill even though the freezer cooling is off. This continues until the freeze point of my wine has been reached somewhere below the 28 degrees... and you guessed it, the wine began to freeze.

Now I caught this before the carboy broke but I expect the wine is lost.

Lesson: Don't use your carboy for the temp reference in a freezer system. I've continued this process with the thermocouple hanging in free air. Yes the freezer cycles more initially but the brew does reach and stabilize at the set temp without the undershoot freezing the bejesus out of things.

I don't even want to think how things would have turned out if I hadn't checked things when I did...

 

[cactusgarrett]

Ice wine?

 

[GilaMinumBeer]

This si why a dual stage controller is ideal. Set the cooling for the preferred wort temp and then the heating stage for a couple or few degrees below that.

This won't change the fact that your freezer still drive down into the single digits but will keep your product from freezing.

 

[jcalisi]

I use a small plastic tube filled with the gel from a freezer bag and a lid with a hole in it for the thermocouple. That way its doesn't cycle as much as free air and has less of a thermal mass to read from. Usually when I go from 65 to 37.5 it will overshoot by about 2 - 3 degrees but thats it. Once it normalizes it runs fairly smooth.

 

[bja]

Now I caught this before the carboy broke but I expect the wine is lost.

Why would that have hurt the wine?

 

[Bumbler]

I had the same problem, then I started strapping the thermocouple to a pint mason jar w/lid filled with water that stays in the fridge. Works great. No overshoot on a hot pull down.

 

[Sudz]

Thanks for the feedback guys. I had considered using a smaller mass for the thermocouple reference. Think I give it a try since it seems to work for a couple of you.

And with regard to the slightly frozen wine... it may be fine I don't know. I've experimented with making wine Popsicles before and it simply ruined the favor of the wine (same with beer). So we'll wait and see how it plays out. For sure I'm not dumping the wine without some careful consideration.

Cheers....

 

[bja]

I've mistakenly frozen beer before and it was fine after thawing.

 

[GilaMinumBeer]

Thanks for the feedback guys. I had considered using a smaller mass for the thermocouple reference. Think I give it a try since it seems to work for a couple of you.

And with regard to the slightly frozen wine... it may be fine I don't know. I've experimented with making wine Popsicles before and it simply ruined the favor of the wine (same with beer). So we'll wait and see how it plays out. For sure I'm not dumping the wine without some careful consideration.

Cheers....

You did it wrong. You were supposed to remove the ice crystals after they froze to concentrate the yummy goodness left behind.

 

[Sudz]

You did it wrong. You were supposed to remove the ice crystals after they froze to concentrate the yummy goodness left behind.

Not surprising... I'm generally pretty good at doing something wrong

 

[dstar26t]

For crash cooling, I set the controller for 40F, when everything equalizes (24 hours), turn down to 34F and wait for equalization again, then turn down again to 30F. My probe is taped to one of 2 carboys and insulated with a towel.