Johnson A419 Temp Controller Problem

I had one of those. I broke it in about 3 years. I think it had a lot to do with the fact that my garage was not temperature controlled.

As for your problem, try to set the OSF and the FS up a little. None of those numbers need to be zero to get you into a good regulated The Dif can be 2 or 3 as well. The ASd can be set to 10 or 12.



http://www.johnsoncontrols.com/cont.../temperature/electronic2/a419singlestage.html


http://www.beeradvocate.com/community/threads/how-to-rock-a-johnson.31212/

 

Mine acts the same way so I am interested in any responses.

During active fermentation, I just set it at the temp I want to ferment at. I figure my too cool freezer will counteract the heat given off by fermentation. I don't have a thermowell, so that's how I've been dealing with that. After it dies down, I crank it up 3-5 degrees since (like you said) that's where freezer seems to always be at. For reference I have my probe wrapped in plastic in a 20oz water bottle wedged in the corner behind my carboy.

Beers have been turning out fine, so I've just been going with it.

 

At what temp do you observe the freezer turning ON? The freezer should turn on at 68 and it could easily drop such a small body of water into the low 60's even once it turns back off.

I dont think you have a problem here. The point of the controller is to turn on the freezer if the temp goes above the set point. It will not necessarily hold an exact temperature. If the ambient temp in your basement is 65 then the water will settle out at that and the controller would never need to come on. There is nothing going on in the water that would raise its temperature like there is with fermentation.

If you really want to test the controller fill the water bottle with HOT water and see if it activates the freezer.

 

If you have an accurate thermometer, use it to see if the a419 reads the same temperature.

 

be sure your freezer is working properly without the outboard controller.

also, the chest freezer has a lot of heat removal capacity and it is possible to blow right by the cut off set temp. even when turned off the coils are cold enough to continue the chill the interior. so pay attention to the actual interior temp, especially if you are trying to maintain 68.

Cheers.

 

The average temperature of the fridge and any (non-fermenting) liquid inside will always be lower than the setpoint of the controller, due to the aforementioned swings. Yes, the volume of a carboy will buffer against the magnitude of the liquid's temp swings, but its average temp will still be lower than the setpoint.

I use one controller to control the fridge's average ambient temp, with its probe in the air space, and a second controller whose probe is in a thermowell in the carboy. The second controller turns a heat wrap on/off. The first controller's setpoint is a couple degrees above the ambient temp I want. (And that ambient temp I shoot for is about 7 degrees below the fermentation temp I want). The second controller's setpoint is set to the desired fermentation temp.

This combination locks in the wort/beer temp very well, without having to continually adjust a single controller to compensate for the varying heat produced by the fermentation (if the single probe were to be in the air space), or having to worry about the phenomenon @billandsuz mentioned (if the single probe were to be in/on the fermenter).

 

Again, my situation sounds very similar to @wineshop. My thermometer reads what the Johnson display does.

@Mag00n, I've never seen the display higher than what I have the set point at, but I've never just sat there and watched it for hours either. So I assume it either never gets above the set temp, or it immediately kicks on and brings it down when does get above it. But it brings too low (so I think, at least), where the temp is 3-5 degrees lower than the set point. I know this is the temp of my water bottle and not my beer, but thats why I jammed the bottle in the corner with the fermentor up against it. To come closer to matching the temps. There doesn't appear to be any coils in that part of the freezer, but I may be wrong or it's close enough that the metal is cold enough. My rationale might be completely backward.

@VikeMan, are you saying it's impossible (or close to it) to lock in a temp with one controller with a probe directly in the beer?

I guess my frustration lies in that there is a setting called a differential, and if you set it to +/-1, what you actually get is 0 to -5. Why does it never get to +1 and why does it not cut off sooner?

 

It was impossible with the two fermentation freezers I have used, because the wort was still getting colder for a while after the power was cut off. I won't say it's impossible for every freezer, but it was for mine.

The DIF setting is not +/-X, as in "both over and under," it's -X in cooling mode and +X in heating mode. So say you're in cooling cut-in mode, with DIF set to 1 and SP set to 68. It will turn on at 68F and off at 67F. When I saw turn off, I mean the controller will cut off power to the freezer. If the probe is in/on the wort, the freezer may have got very cold by the time it moves the wort temp to the cutoff point (SP minus DIF), so the wort gets even colder as it and the freezer interior move toward equilibrium with each other, even though the power has been cut off.

 

Thank you Vike, that makes sense.

Aside from another controller and/or a thermowell, do you think my current practice of setting the controller at what I want to ferment at (as described in my first post) is the best I can do in my situation?

 

I depends on the yeast. Some yeasts will work fine at a temperature lower than its specified range.

 

You mean set it a couple degrees high, so that it averages the temp you want? Yes, I suppose that would be the way to go with a single controller if the probe is measuring the wort temp. The temperature swings may or may not be acceptable to you. Another option would be to put the probe in the air space, and set it so that the resulting average fridge temp is a few degrees below your target fermentation temp. And maybe adjust the setting upward as fermentation slows down (when the fermentation is producing less heat).

As Betty said, that would depend on the strain. I will say though that many strains are capable of fermenting at temperatures lower than what the manufacturers suggest in their published ranges. Even so, keep in mind that the lower the temperature, the slower the fermentation will be, and generally you'll get less esters, which you may or may not want.

 

You will have less temp swing with a larger body of water/more things in the cooler. When I want to ferment at 67 I set the SP to 68 and I get temps from 65-68

 

Anyone ever get a CO3 fault code? I've unplugged mine and plugged the freezer directly in and the compressor runs, but it does not get cold. Probably going to go buy another freezer, but was wondering if the controller needs to be reset now somehow. It's been ~ 3 year run with the controller and ~ 25 yrs with the freezer. TIA