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Old 08-04-2010, 09:16 PM   #1
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Default Johnson A419 Temp Control settings for fermentation?

I've finally juggled some things around so I now have a fridge I can use to control fermentation temps. Since it's summer, that just means cooling so I'm using a Johnson A419 controller and a carboy cap that allows me to get the probe into the center of the fermenter.

If I want to ferment at 66, how "tight" should I set the controls?

Right now, I have SP=68 and DIF=2 so the fridge kicks on when the probe reads 68 and shuts off when it reads 66. Since it's chilling from the outside in, I figured having the higher set point makes sense since the outer wort would likely be at a temp below the shutoff temp.

What I'm most curious is what others use for the DIF. Should I set to 1 or even 0? Is there enough thermal mass that the fridge won't be constantly turning on and off? Or, should I set the DIF to 0 (or 1) and up the ASDL delay from 5 to 15 minutes to save wear and tear on the fridge?


Atomic Dog Brewery

On Deck: Centennial IPA, Dry Irish Stout
P: Cascade Pale Ale
S: (nothing!)
K: (nothing!)
T: Carbed Crystal Light, Root Beer, Vanilla Cream Soda, Tripel IPA, Apfelwein

e^(pi*i) + 1 = 0
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Old 08-05-2010, 12:22 AM   #2
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I have mine at 2 differential and ASDL is 12.... That's for a Keezer.
For my fermenter I have a Love controller with a tighter diff, I think it is .5 .

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