Brite Tank Freeze Up

[Blu Dragonfly]

We had a 10 BBL brite tank freeze up several batches ago on a 4.5% ABV beer. I'd been setting crash temps at 32-33F with the understanding you will get a slight possible over-shoot but with 4.5% and higher batches, our freeze point should be 30 or lower. We checked our thermowell as well as the probe and controller calibration using ice water and it was within .1 degree.

The first time we saw this during packaging, the tank controller was showing a 29.6 F product temp which didn't concern me until we opened the tank after we were done packaging.

We started setting the tanks at 34-35F to prevent this. The last two batches were just fine, this latest batch (back to the 4.5% beer) it had a 6-12" thick band of ice all across the middle jacket of the tank approximately 30-36" tall.

The second time, our temperature reading indicated on the controller was 34.2F.

We keep our glycol set point at 21F to provide excess cooling for crashing. Our system uses individual Inkbird controllers on our tanks and our larger set of fermentors uses small pumps submersed in the glycol rather than a loop with solenoids (our smaller set uses a loop and solenoids and has never frozen a tank even set at 32F).

The only explanation I can find is if we've got a siphon going on when the pump shuts off, in which case a low pressure spring-type check valve on the return would fix this. This really seems like a remote possibility as the tank should be showing the beer is cold enough to freeze. When we looked in today, the thermowell was not covered in ice and I'm aware that ice on a thermocouple will act as an insulator.

Anyone else ever experience this?

Thank you in advance!

[dick murton]

Where is the temperature probe located? Once water (and most beers - including ones at that ABV) get below about 4 deg C, the liquid becomes less dense and rises. So a low level probe will not be measuring the coldest liquid, and thus will demand more cooling - hence the ice. This is potentially a major problem in tall vessels so are often fitted with high level probes as well as one just above the cone for fermentation. Less common in small vessels, but not impossible - think puddles and shallow ponds freezing over top down.
If you haven't got two probes, and most that size don't, I suggest you raise the temperature of the glycol to say 3 deg C and if you need to cool further, reduce it once you tank has been stable at say 4 deg C for 24 hours so you can get to your desired temperature. Less desirable perhaps, but easier would be to trickle a little co2 through the tank once you get to say 5 deg C, to mix the beer, wait a couple of hours and repeat, repeating again if necessary.

I am sure other people have different alternatives

[lhall]

I think 21 F is too low a setpoint for your glycol. 28 - 30 F should be plenty cold enough. Your chillers probably aren't designed to operate at such a low glycol temperature efficiently anyway, and having it set so low will definitely cause freezing in your brite tanks.

[Blu Dragonfly]

Thank you guys, I raised the glycol temp to 30 and I did remember we put check valves on the returns when we constructed the system so that was not it.

FYI, the probe is in the lower 25% of the tank. I don't have any other blocked triclamp fittings higher up so no easy way to add an additional probe. We'll keep it at 30 from now on. Even our lowest ABV beers should not freeze with 30 degree glycol.