Fermenter Control Chill/Heat with Water

Hello,

I'm just wondering if the control theory behind this setup would work or not. Please see attached pdf.

Assumptions:
both controllers are given the same setpoint.

The water reservoir is a Cornelius CR50 chiller with submerged heater and submerged circulation pump. Another submerged pump circulates water through coils within the fermenter.

Thanks

View attachment Temp Control Circuit.pdf

It is a neat approach, although I suspect you will find that you need an offset in the fermenter side to account for temperature gain/loss between the CR50 and the fermenter.

The wiring on the CR50 side won't do what you're thinking though. In that configuration both the heat and the cool will run any time the STC kicks on.

If you want Heat+Pump or Cool+Pump you need a third relay in the system. Simplest would be a relay with a 120v coil so that you could branch off of the heat and cool lines to directly turn the pump on and off.

The other approach would be to just let the CR50 pump run all the time.

Why not just continuously run both pumps and only use one controller to heat or cool the the reservoir water based on the temp of the fermentor? You should be able to get away with cheap 12V or 24V pumps too.

BeardedBrews said:

It is a neat approach, although I suspect you will find that you need an offset in the fermenter side to account for temperature gain/loss between the CR50 and the fermenter.

Click to expand...

Sorry, I don't quite follow. Do you mean a wider tolerance on the fermenter?

BeardedBrews said:

The wiring on the CR50 side won't do what you're thinking though. In that configuration both the heat and the cool will run any time the STC kicks on.

If you want Heat+Pump or Cool+Pump you need a third relay in the system. Simplest would be a relay with a 120v coil so that you could branch off of the heat and cool lines to directly turn the pump on and off.

Click to expand...

Well of course it won't. Thanks for pointing out this major flaw.:smack:

chudsonvt said:

Why not just continuously run both pumps and only use one controller to heat or cool the the reservoir water based on the temp of the fermentor? You should be able to get away with cheap 12V or 24V pumps too.

Click to expand...

The main reason is the nagging feeling of wasting electricity. But because the coil circulation pump in the CR50 is coupled with an agitator paddle, this solution becomes simpler and that much more attractive.

Cheers

Surfmase said:

Sorry, I don't quite follow. Do you mean a wider tolerance on the fermenter?

Click to expand...

I mean if there is 1f in temperature loss in the tubing, and another 1f in loss due to poor insulation on the fermenter, then you will have to offset your bath temperature 2f to get the temperature you want in the fermenter.

Not a big deal, was just pointing out that the two controllers would probably not operate at the same setpoint.