Johnson Controls - WTF ?

Had 2 (analog, not digital) since about 2004

Before Katrina (not my daughter - the hurricane), I was very anal about monitoring temps using a graduated cylinder with water in the freezer and a digital thermometer.

I also monitor clarity with a 14-16" cylinder with a sample after I rack to the brite tank - gives me an idea of how the beer is clearing.

Noticed over the last week or so, that even though I had the control set at 36 F (I wanted an average temp of 34 F), that the beer in the cylinder was freezing.

I checked again today, after raising the controller temp to 38, and the beer in the cylinder was freezing again.

I checked with a digital thermometer, and my beer in the cylinder was 30.6 F -- this is where the WTF comes in - 38 on the controller should give me an average temp of 36 F - I just raised it to 40 F and will check again in the morning.

My chest freezer is a GE (they have become a POS) that is only about 2 years old. BUT, the controller should regulate the temps.

I have nothing else in the freezer that would interfere with the probe recognizing what the temp is - it is positioned so that it is in free air space and not touching anything.

Q for the more advanced brewers - should I put the probe in liquid to register the temps better ? (had not done this in the past, and did not have trouble keeping temps within range of what I told the control to do)

Guess the point is, be anal about your temps and use a secondary method to monitor temps. Just setting the control at a certain temp does not guarantee that that is what reality is.

I guess it's like the old expression: "never trust a fart"

Hope this helps some of the newbies and intermediates avoid potential problems (temp showing X, and it's really Y - could interfere with fermentation times)

Submerge the temp probe in a bottle of water. This will keep it from kicking on every time you open the lid. The temperate of a liquid changes much slower than the temp of air.

I have a lagering fridge and a keezer. I use Johson analog on both. My probes hang down freely in the air. I never went to the trouble of using water for the probe and have tested with a milk thermometer and the temps have been right on.

Check the docs to see if you can calibrate that controller. It sounds off to me.

bannonb said:

I have a lagering fridge and a keezer. I use Johson analog on both. My probes hang down freely in the air. I never went to the trouble of using water for the probe and have tested with a milk thermometer and the temps have been right on.

Check the docs to see if you can calibrate that controller. It sounds off to me.

Click to expand...

I'm sure it's off. I have it set at 40 F for the last 2 days, and the actual temp of liquid in the freezer is 31 F

I have another controller - I'll look around and see if you can calibrate them.

Thanks (yes, just hanging in open air used to work fine - they are about 8 years old, so maybe it just croaked a little)

It is quite possible that it's just your probes are getting older and you may need to clean them up and/or change them. They don't last forever and the resistance changes over time as the metal corrodes, etc.