Johnson Control Unit

[Garrete]

I have a Johnson control unit. I have a washcloth folded up and taped to the outside of my glass carboy and put the probe between the glass and the washcloth. I also have an indoor/outdoor thermometer that I place the sensor under the washcloth as well. This has been doing fine, until lately. I had the control dial set to 62* and the temp read 70*. Also I am getting big temp swings that I used to not get. Any ideas of what I can do to fix this? Is my temp control unit dying on me? If it is, is digital better?
Thanks in advance.

[linuxelf]

When you were noticing the high temp, was the temperature controller supplying power to the fridge? Could be your fridge giving out? I've got an analog Johnson controller, and get the predicted 4 degree swing in temp, but I've never seen it vary by 8 degrees in one direction before.

[Garrete]

I will have to pay attention when that happens. I hope it is not my chest freezer, I just bought the thing not more than a year ago.

[Bugeater]

I have a couple of those analog Johnson controllers and use indoor/outdoor thermometers like you do. I find the the scale on those controllers is so small that it is pretty much impossible to get an accurate setting. I rely on the thermometer and tweak the dial on the controller until I get the temperature I want.

You should also make sure you are getting good contact with the probes and the fermenter. I tape mine to the glass and then cover them with some bubble wrap for insulation. I would stay away from using a washcloth as this could soak up a little moisture. Evaporation from that when the fridge fan comes on will affect the temperature readings.

Still, it sounds like you may have other problems. Could be the controller, the thermometer, or the fridge. Check the cheapest item first.

Wayne
Bugeater Brewing Company

[BadRock]

How old is the unit in question? These old style controllers are mechanical thus it is a matter of time before the springs start to weaken and so on. Sounds kind of like what you have going on. They will continue to work, just your degree of accuracy widens.

[Mylo]

I have a Johnson control unit.

I have two. Ages 7 and 9. Every time I think about using my Johnson - I remind myself that two are enough.


Mylo

[Garrete]

The Johnson unit is about as old as the freezer, less than a year. Without having to buy a new unit, is there a way to check if mine is going bad?

[baltobrewer]

I have a Johnson control unit.

I have two. Ages 7 and 9. Every time I think about using my Johnson - I remind myself that two are enough.
Mylo

only 6 posts! suprising, considering that both the words "johnson" and "unit" were in the post title......