Ranco Controller

[MikeDelta1]

I'm having a problem with my fermentation chamber set up. I have a 23 cf freezer (got a good deal, figure it will hold 6 brew buckets) that I added a ranco controller to. I set it up to try out, I have it set at 65 with a 2 degree differential. The problem is that when it kicks on it drops it all the way to 59 degrees and shuts off (only runs for maybe two or three minutes), and then it ramps up slowly over about three or 4 hours and kicks on again. It is in my garage downstairs and the ambient temp is around 66 degrees right now. Is this normal? Do I have it set wrong? Is there some sort of circuit protection so that the freezer doesn't kick on for two short of a period? Is the temp swing just because it is empty? I have another controller that I can set up to run a heater if need be but that just seems like it would cause swings in the other direction.

 

[Double_D]

You may have set the wrong temp range. It has a Heating and a Cooling setting just double check. Otherwise make sure you're internal thermometers are accurate. I have one on each of my fridges and they work great.

 

[MikeDelta1]

I've got three fridge thermometers in there and they all read the same. I checked to make sure it was in cooling mode. I think the freezer just cools it down so quick in just the few minutes it runs because there is nothing in there and the ambient temp is only around 66. I'm going to fill up some buckets with water and set them in there and see if that makes a difference.

 

[tincob]

I have a similar issue with a Johnson digital temp controller.

The cooling swings the temperature lower than the set lower bound.

Interested in learning why this might be the case.

 

[yellowthere]

So you have the temp probe just dangling? I think that's the issue. Tape it to the side of the carboy and insulate it with cloth or paper towels. For the purpose of your test, I guess tape it to the side of the bucket, and insulate the same. The issue is that the ambient temp can swing quite a bit, while the large volume of liquid will not. This has always worked for me, I hope that it does for you.

something else to watch out for, is that when you have probe on a particularly hot fermenter, other things in the chest freezer are at risk of being significantly colder than the setting.

 

[MikeDelta1]

I put a couple of buckets in to ferment with the little stickers on the side and adjusted the ranco to 64 with a 3 degree differential and the buckets seem to be holding at 68, so I dropped it to 62 which should work for me. I'd like to be fermenting around 65. I left the probe dangling, I guess it is just a case of tinkering and seeing how my set up works. For the next batch I'll tape the probe to the plastic fermentor and set the temp on the controller at 65 and try it that way. Experimentation is half the fun I guess. Thanks for the idea of taping the probe to the tank.