Johnson Controls A19 Calibration

[fknizner]

I purchased a Johnson Controls a few months ago and use it in a Mini-Fridge to create a temperature controlled fermentation chamber. It works incredibly well at controlling temperature, and my beer quality has drastically improved.

I've done about 10 beers using the controller in my Fermentation chamber, and I've kept track of (among other information) three temperatures: 1) the temperature that I set the dial/knob at; 2) the ambient temperature of the fermentation chamber; and 3) the temperature reading on the fermometer (i.e., best guess at beer temp.).

Naturally, during fermentation, the degrees can be drastically different. I may have the dial set on 48, creating an ambient temp of 55, with a fermentation temperature of 60~62. Obviously during any fermentation the fermentation temperature will be greater than ambient. After fermentation completes, I will have raised the dial to ~54, creating an ambient of ~61, and the beer will be 60~62. As the beer stops fermenting, it goes back to the ambient temp. This all makes sense.

However, it it appears that the actual ambient temperature of the fermentation chamber is about 7~8 degrees greater than the reading on the dial.

To remedy this, I believe I must re-calibrate the Johnson Controls unit.

Could anyone with experience with the Johnson Controls Analog A19 unit tell me how I re-calibrate it so that the temperature I set on the dial will be equal (or at least closer) to the actual ambient temperature?

 

[mrklueber]

I have used these controllers for years and never figured out how to calibrate the dial. I just used an independent thermometer to measure the ambient temperature of my fridge/freezer and set the dial to achieve the desired ambient temp.

 

[fknizner]

Yeah, that's what I've been doing too. I was afraid that might be the answer, but oh well.

 

[TheDecline]

These controls are factory calibrated. They are not meant to be field calibrated. The only thing you could do is try and free the dial and then adjust it to a known temp and then re-secure it. Or cover the marks on the dial and just write in your own. Otherwise, get a better controller.

Also, make sure its mounted on a flat surface and make sure there is no stress on the frame of the control from mounting screws.

I work with these things often. They are usually accurate to a few degrees Celsius but they aren't meant for super precise control.

 

[fknizner]

Or cover the marks on the dial and just write in your own.

Good idea, I'll just do that. Thanks.

 

[natefrog255]

I just got the JC Analog and seems like mine is about 4-5 degrees off (ie. Set at 35, air temp is 40). Well assuming my external thermometer is right. I guess I can just adjust accordingly. I have sensor hanging in middle if fridge with tip touching fridge bottom. Was hoping it be a little more accurate.

 

[natefrog255]

Mine seems to be getting farther off, like 8-9 degrees. And then my beer temp is even a bit warmer. I had some foaming issues and finally checked the beer temp, it was a ton warmer than expected.

I don't really want to install a muffin fan, but think it may be a good idea to get the top of the mini fridge more cool.