Johnson Control's: Digital Temperature Controller (heating) Questions...

Hi,

I have a Digital Temperature Controller that i want to use with a Fermwrap (heat blanket) for my carboy. I know that i have to open up the box and change the jumpers to work for heating mode. I want to have the set point at 68F with the differential set point at 2 degree (cut in/out).

Question(s):

Do I want to set the jumpers to cut out at 68F or do i want it to cut in at 68F.

My thought was to have it cut out: The blanket will stay on tell 68F (plus the 2 degree differential cut in/out) and once it is up to 70F the Digital Temperature Controller will cut out and will not cut back in tell it drops below 66F (2 dergree differential setting).

Yes. If you ambient temp is below your desired ferm temp, then set it to heat and cut out at 69. I personally set my dif to 1, so it turns on at 67, but it's the same concept. I would also suggest wrapping a blanket around the fermenter on the outside of the fermwrap to help insulate it.

JJL said:

Yes. If you ambient temp is below your desired ferm temp, then set it to heat and cut out at 69. I personally set my dif to 1, so it turns on at 67, but it's the same concept. I would also suggest wrapping a blanket around the fermenter on the outside of the fermwrap to help insulate it.

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Thanks fo the info!

So if you set the dif to 1 (set point cut out @ 68 F) then it will turn on at 67F then turn off at 69 F (dif 1). I did not think about it cutting in before the set point (dif setting)...long wk :cross: That might be a better idea to set it at a dif of 1 so it does not cut out at a high temp.

It's kind of odd the way it works. I have mine set to heat with a cut out of 69. My dif is 1. Keep in mind I haven't really watched the thing in action since I first got it, but IIRC this is what happens. The controller powers the heater until the temp reading just barely hits 70. Then the controller cuts power to the heater and the temp drops immediately back to 69. The heater stays off until the temp just barely drops to 67. Then the controller kicks on sending power to the heater and the temp immediately pops back up to 68. The heater then stays on again until the temp just barely hits 70.

Good luck with your setup. I get a lot of use out of mine.