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-   -   Johnson Controller temp probe location - keezer (http://www.homebrewtalk.com/f51/johnson-controller-temp-probe-location-keezer-378086/)

CButterworth 01-02-2013 08:38 PM

Johnson Controller temp probe location - keezer
 
My Johnson A419 arrived today and I want to get it set-up in my DIY keezer.

The desired temp of my beer is around 54F.

The question is how to place the probe to reduce temperature swings of the beer in the kegs AND reduce strain on my keezer. For this reason, it seems that I have two major options, plus many in-betweens:

A. Attach probe to side of keg with plumber's putty (as read in a previous thread). Given the lag in warming/cooling of a full keg of beer, I would expect to set a very small/narrow temperature differential (maybe 1F).

OR

B. Let the probe hang freely in the center(ish) of the keezer and use it to monitor air temp. Given that the air temp would likely fluctuate more than the beer temp, I'd set a much larger temperature differential (maybe 5F).

Personally, I think that both of these methods ought to keep the liquid in the kegs at a fairly stable, constant temperature.

Can anyone offer any comments or suggestions.

Thanks,
Charlie

ibbones 01-03-2013 03:46 PM

I took a piece of insulating material that we got in the mail for meds and use a bungie cord to wrap around the kegs with the probe right next to it and under the insulating pad.

m1k3 01-03-2013 04:30 PM

I use option C - The probe taped with painters tape to a beer bottle laying on the bottom of the freezer.

I use the Johnson A419, set to 35F, +/- 3F, anti short cycle delay set to max = 12 minutes. (It's an old freezer and I don't want to kill it.)

kblankenship11 01-03-2013 04:35 PM

I keep mine in the center of the keezer. You will put more of a strain on your freezer motor, but your beer temps will stay consistent. I have a Johnson controller set to 37 with 5 degree differential. So when it hits 42 it will chill down to 32 and go through the cycle again.

My buddy drilled a hole in a water bottle and stuck the probe in the top. The bottle will change temps slower than the air but quicker than your kegs, so it's a good middle ground. You might want to go that route with 1 or 2 degree differentials since your holding temp is on the higher end.

Monster Mash 01-03-2013 05:05 PM

Quote:

Originally Posted by CButterworth (Post 4739234)
My Johnson A419 arrived today and I want to get it set-up in my DIY keezer.

The desired temp of my beer is around 54F.

@ 54 degrees you will be getting a lot of mold from condensation, it is best to keep it in the upper 30's and if you want to drink your beer in the 50's let it warm up a bit.

CButterworth 01-04-2013 12:46 AM

Quote:

Originally Posted by Monster Mash (Post 4742419)
@ 54 degrees you will be getting a lot of mold from condensation, it is best to keep it in the upper 30's and if you want to drink your beer in the 50's let it warm up a bit.

I am hoping that I can take a few precautions to avoid a build-up of mold, while still keeping my keezer at 54F:

1. Luckily in my part of the US (Denver, CO), relative humidity is relatively low (20%'ish). I expect that this will result in less condensation than, say Iowa and other parts of the Midwest.

2. A regimen of sanitizing the interior of the keezer ought to help. I plan on using One-step in a hand spray bottle, every now and then (maybe when I change out kegs, or something.

3. Dehumidification, such as Damp-rid, refueled by bulk purchased Calcium Chloride.

4. Mopping-up spills to at least keep attractants out of the keezer (not that molds actually get attracted!).

With any luck, I'll be able to avoid a moldy keezer.

Thanks for the replies, so far I am trying air temp with the following settings:

Setpoint: 54F cutoff
Diff: 4F
12 minute delay to avoid short-cycling

While this will result in greater than 4F swing in temp of the keezer, I hope that the thermal properties of the beer in the keg will result in very little temperature swing of the beer, and infrequent cycling of the keezer. I am going to borrow a temperature logger to test this assumption. Then, I'll switch to the probe-on-keg method and test that.
Charlie

CButterworth 01-04-2013 12:51 AM

Quote:

Originally Posted by m1k3 (Post 4742290)
I use option C - The probe taped with painters tape to a beer bottle laying on the bottom of the freezer.

I use the Johnson A419, set to 35F, +/- 3F, anti short cycle delay set to max = 12 minutes. (It's an old freezer and I don't want to kill it.)

I may try this too.

As for the differential setting, according to the instructions for the A419, the differential works differently depending upon whether your controller is set to switch off or on at the set point.

For example, if set at 35F cut-off with a 3F differential, the controller would switch on the freezer at 38F and switch it off at 35F. BUT with the controller set at 35F switch-on and 3F differential, it switches on at 35F and off at 32F.

As far as I can tell, the differential is not +/- at the same time.

Charlie

Cbaddad 01-04-2013 12:53 AM

In mine, I filled a beer bottle with water and got the appropriate size bung with a drilled hole. Place bottle at the bottom and put temperature probe through the hole in the bung to the water. Keeps things dialed in perfectly IMO.


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