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Hey keggers, need recommendations for setpoint/differential

to ferment at 50, do I set the “set point” at 50 and then the “dif” at 1 or 2? Default “dif” is 5, but that seems a bit much. Or, is it ok as it is the air temp being measured in the freezer, not the actual beer temp.

:cheers:

To ferment at 50°F, I’d set the setpoint at 48°F and the differential at ±2°F, or even ±4°F. The liquid temperature won’t change nearly as quickly as the air, and you don’t want to cycle the compressor unnecessarily.

Edit: The actual settings will depend on how your controller works. If the differential only goes in one direction, then I’d set at 50°F with a 4°F differential, or 52°F with an 8°F diff, etc.

Which controller do you have?
Where will you put the sensor? If you want to control the fermentation temperature with a digital controller, I would recommend a thermowell or at least taping the sensor to the side of the fermenter and then taping some insulation or bubblewrap over it. Then I would recommend a 1degF differential.
:cheers:

In your scenario I set mine at 49F with a 2 degree differential. The sensor is tight against the fermenter and insulated from the surrounding air. The AC unit cycles every hour of so during high krausen and less after the fermentation subsides. Initially I tried 1 degree differential but I felt the AC cycled to often. Cheers, and Happy Brewing!!!

I alway set my setpoint one over the actual temperature that I want it to be at since it always seems to be on the colder side. I usually do three on the differential, and it is always within one or two degrees of where I want it. But definitely take the temperature of your liquid, so don’t just have the probe sitting in there touching the freezer or in midair.

[quote=“TG”]Which controller do you have?
Where will you put the sensor? If you want to control the fermentation temperature with a digital controller, I would recommend a thermowell or at least taping the sensor to the side of the fermenter and then taping some insulation or bubblewrap over it. Then I would recommend a 1degF differential.
:cheers: [/quote]

I have the Johnson Digital Controller, model A419ABG-3C. Bought from NB in 2006 when I first starte to brew but it’s not been used until last week.

The sensor is just hanging in the freezer, suspended, not touching anything and sensing the air at approximately 3/4th of the way up the carboy from the bottom.

FWIW, DIF ranges from 1 to 30. According to the instructions, it “establishes the difference in temperature between the cut-in value and cutout value…it is set relative to Setpoint…”

So, if I set the set point at 50F and DIF at 2, will it stay on in the range between 48F and 52F? Cutting off when it goes below 48F and cutting on when it exceeds 52F? That’s what I’d like.

cheers

Stormy, I have the same controller and it works great. If you set it up like you mentioned it will do just that. Like i said before though-don’t just have it hanging in there, you need to take the temperature of your liquid otherwise it will never be where you want it.

Or I guess I should say that it will possibly cycle on and off more frequently if you just have the air temp. The liquid won’t fluctuate like the air will.

It sounds like if you want the range to be 48-52°F (and it’s cooling), you’d set it for 48°F with a differential of 4°F. I know that’s how the Ranco ETCs work, but it’s been a while since I’ve had to adjust a Johnson. (Sorry, couldn’t resist.)

I have the probe in mine (ouch! sounds painful) just hanging in the middle of the fridge. So should it be placed somewhere else? Like tapped to the fermentor?

If you want the controller to control the fermentation temperature you can use a thermowell or just tape it to the side of the fermenter and then tape some insulation or bubble wrap over it. Then I would recommend a 1degF differential.

+1. Since I use buckets for primary fermenters I go with the thermowell, due to the rather thick bucket. A temp controller probe under a few inch square of doubled bubble wrap taped against a carboy will identify the beer temp within about 1 degree.

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