Johnson Temp Controller

[shibbypwn]

I just hooked up my Johnson temp controller- and it's not being very stable temp wise.

I've set it to 61 degrees, with a differential of one degree.

The compressor comes on at 61, and cools it down to about 55 degrees- so not exactly stable.

It seems that the compressor just stays on too long- and the temp continues to drop after the compressor clicks off.

Any suggestions as far as settings to stabilize the temp?

 

[Haputanlas]

That doesn't make sense. If the controller was working properly, your compressor would stop completely once your temp was reached. I'd be more concerned with the controller than anything else.

 

[Chefencore]

Is it hooked up correctly? I mean is your fridge plugged into the controller?
Try giving it at 2-3 degree differential, see what happens.

 

[shibbypwn]

Ya... Mine clicks on at 61, cools down below 61, and then shuts off. I'd expect it to cool to 61, shut off, heat to 62, then click back on

 

[Haputanlas]

Weird, doesn't make sense to me. I agree with chefencore. Try a different differential and see if things change. Or you can try a different temp.

 

[Haputanlas]

Also, you should probably put a thermometer in the chamber just to verify the temps are correct.

 

[DeafSmith]

If you are using the factory default setup and have the set point at 61 and the differential of 1 degree, the compressor should turn on when the temperature rises to 61 degrees, then shut off when it falls to 59 degrees. After the compressor turns off, the temperature will continue to fall because the walls of the fridge/freezer and the air inside are all much colder than 61 degrees. How much lower the temp. will drop depends on the thermal mass of the metal and air and beer and on how you mount the temperature probe - free hanging, in a thermowell, taped to the side of your carboy with insulation over it, etc.

 

[Chefencore]

[URL="http://cgproducts.johnsoncontrols.com/MET_PDF/125188.PDF#xml=http://cgproducts.johnsoncontrols.com/search_lit.aspx?cmd=pdfhits&DocId=4900&Index=C%3a%5cinetpub%5cwwwroot%5c72%2e3%2e145%2e66%5cquicklit%5cexcaliburCD&HitCount=95&hits=4+10+20+5a+68+94+b2+173+1a1+1b4+1e2+1f2+205+33c+346+36c+376+385+393+39c+3ae+3b0+3b9+3f7+477+49b+577+598+5da+5f6+610+635+645+78c+7a7+811+82e+917+92b+9e2+a13+a4e+a7b+a93+ac0+b63+b6a+b8a+b93+b98+bb3+bbc+bc0+bdd+bea+c3d+c95+ccf+d81+da3+dcc+e52+e5d+ec7+1015+1052+105f+10c6+1209+129d+12a5+12ba+12f4+1306+131b+1394+13db+13e2+13ec+13f3+1427+142e+1438+143f+14d4+14ff+1505+1512+1518+1528+152d+1543+1548+1651+1688+&hc=189&req=a419*”]This[/URL] is the manual for the controller. It describes what the jumpers do and how to set them. I use cut-in, which turns the fridge on at my set temp, and cools it to Temp minus Diff degrees. I’m not lagering right now, so my differential is 3 degrees. That keeps the controller from cycling the fridge too often. You can go the other route, which is cutoff/Cut-out. It cools to your set Temp, and turns on when the Temp + Diff occurs.

Edit - Did you buy this from Johnson, or New from a reputable source? If not, do not assume that it is at factory default settings.

 

[Haputanlas]

If you are using the factory default setup and have the set point at 61 and the differential of 1 degree, the compressor should turn on when the temperature rises to 61 degrees, then shut off when it falls to 59 degrees. After the compressor turns off, the temperature will continue to fall because the walls of the fridge/freezer and the air inside are all much colder than 61 degrees. How much lower the temp. will drop depends on the thermal mass of the metal and air and beer and on how you mount the temperature probe - free hanging, in a thermowell, taped to the side of your carboy with insulation over it, etc.

That's not how mine works (Ranco). If it were set to 61 degrees with a 1 degree differential, it would wait until it hit 63 to go back to 61.

 

[DeafSmith]

That's not how mine works (Ranco). If it were set to 61 degrees with a 1 degree differential, it would wait until it hit 63 to go back to 61.

I don't know how the Ranco's work. I was just talking about my Johnson.

 

[Haputanlas]

I don't know how the Ranco's work. I was just talking about my Johnson.

Understood, I just wanted to clarify that different controllers act differently. We can all agree that something is weird about his config.

 

[shibbypwn]

So, now I've got a carboy full of beer in there- sensor taped to the side, insulated with a sock- the temp is still swinging, but not as much.

I have it set to 66, and it swings from 65-63.

Im thinking maybe I didn't insulate well enough, and I'm still getting air temps?

 

[rexbanner]

So, now I've got a carboy full of beer in there- sensor taped to the side, insulated with a sock- the temp is still swinging, but not as much.

I have it set to 66, and it swings from 65-63.

Im thinking maybe I didn't insulate well enough, and I'm still getting air temps?

I really wouldn't care. Your beer isn't going to swing as fast as the air temp. Do you really care about 2 or 3 degrees for an ale anyways? Frankly, if you're not using a thermowell then you aren't getting perfectly accurate temp readings on your beer anyways. I'd set the difference to 2-3 degrees just to be nice to your freezer, too.

 

[shibbypwn]

This is my first fermentation using anything other than an ice bath. Definitely getting a thermowell for the next brew.

I've always heard it preached around here that stability was super important in fermentation- perhaps even more so than cool temps (i.e.- a stable 70 is better than swinging between 62-66)

So basically what you're saying is rdwhahb.

 

[dutchoven]

How big is your fermentation chamber? Fridge, freezer, or something else homemade?

I'm seeing the exact same thing with my Johnson. I'm using a 17-cubic foot upright freezer and I see a bit of swing after the controller stops the compressor. My probe is in a small glass vial filled with water (VOA vial, for those in the know).

I have a set point at 62 degrees (for a Kolsch) and I'll see it swing down to around 58-59 degrees after the controller cuts out. I'm guessing this is due to the thermal mass of the freezer walls, etc. I'm really not that worried about it. Though the air temp may be at 58-59, the temp strip on the side of my carboy reads within the proper range (60-62 degrees).

I'm considering pulling my sensor out of the water and measuring air temps, but have a feeling the beer may actually ferment warmer than the controller shows. The sensor placement debate rolls on ...

 

[tesilential]

How big is your fermentation chamber? Fridge, freezer, or something else homemade?

I'm seeing the exact same thing with my Johnson. I'm using a 17-cubic foot upright freezer and I see a bit of swing after the controller stops the compressor. My probe is in a small glass vial filled with water (VOA vial, for those in the know).

I have a set point at 62 degrees (for a Kolsch) and I'll see it swing down to around 58-59 degrees after the controller cuts out. I'm guessing this is due to the thermal mass of the freezer walls, etc. I'm really not that worried about it. Though the air temp may be at 58-59, the temp strip on the side of my carboy reads within the proper range (60-62 degrees).

I'm considering pulling my sensor out of the water and measuring air temps, but have a feeling the beer may actually ferment warmer than the controller shows. The sensor placement debate rolls on ...

I just dangle it in the air. The wort is usually at the upper end of the temp range that the TC/freezer show. I.e., during primary i set to 61 with 3 differential, actually ferments at 64.