Thermowell use in a fermentation chamber

[eobie]

Had my freezer delivered yesterday and hooked up a ranco dual stage temp controller. I decided to use a Thermowell and my first use was crash cooling a Belgian wit.

Set the controller to 34f with a 2* swing. I'm getting icing on the top layer of beer. I'm guessing because that is reaching freezing temps before the center of the fermenter where the Thermowell is. Is this the normal way of doing things or is there a better way of doing it. My solution so far was to raise the temp to 36f.

 

[wfowlks]

Put a fan inside, because the air becomes stratified. I had that problem to.

 

[helibrewer]

I use a measuring cup filled with water to run my controller and monitor fermentation seperately using a thermowell, then I adjust the controller slowly until my ferm temp is where I want it. The problem with running the controller using the beer volume is that it's such a large volume that the freezer runs a long time before the beer starts changing temps, so the ambient temp can get well below freezing...beer needs to get below 29F before it starts freezing due to the alcohol content, so you must be getting below this for the upper layer to start freezing.

+1 on the fan also

 

[dtfeld]

I built a thermowell to be used in my freezer/fermenter. I used a 6" peice of 1/2" copper water pipe capped off at one end with a fitting to allow my temp probe to be screwed in water tight (I use BCS temp probes) at the other. I fill this with Star San solution. This set up keeps the air temperature from swinging wildly both when the freezer is cooling or if I open the door.

This pic shows three lines, black (the set-point), gray (beer temp of the fermenting beer) and gold (the thermowell temp I use for control). You'll notice the gold line fluctuates up and down about 2-3 degF. The top and bottom represent when the fermenter turns on and off and in this happens about every 10-20 minutes.

The gray line (beer temp) follow the back line (set temp) but lags it by about 8 hours as would be expected trying to air cool a large volume of liquid

Benefits are that nothing freezes (as it might if you use the beer temp) and the compressor doesn't start and stop too often leading to burning it up prematurely.