Using a PID to control fermentation temp

[Ghillie]

I know this is a very old thread but did anyone ever have any more thoughts on this? anyone tried it? I have decided to have a go at using an STC for the cooling side with the STC probe taped to the FV and a PID controlling the heater with the probe measuring the space. I am feeling that in using the STC for both I have found as the OP said that the heater over runs the temp a lot so figured this would be worth a try with the PID "learning" the space . Was wondering about how to set the temps for each of the controllers so they are not fighting each other.

Any thoughts?

I can confirm that everything in this thread about "temperatures over-runing" and the fridge/heater "fighting each other" is complete myth. So if you haven't yet forked out for a PID, I personally wouldn't bother.

I have two under-counter fridges both fitted with ITC-1000 controllers and 60W tube heaters; been using them religiously for the last 18 months. It is physically impossible for a 60W tube heater to cause 20L+ of beer to climb past a setpoint. Absolutely impossible with the temp probe stuck to the side of the FV and insulated from ambient. I know this because I've watched it scores of times on hot days, cold days, rainy days, Tuesdays...

dS - 0.5C-1C
cd - 10 minutes

With the above settings in both my setups there is zero issue.

Maybe I'm missing something, or overlooking an error that I'm lucky enough to not be doing?

 

[David Woods]

Hi, I think the OPs point and mine is that when the heater kicks in and the stat reaches temp then the heater turns off there is a lot of residual heat so the temp maybe keeps on rising so then the cooling kicks in and so on.

I take your point and I was thinking for the sake of £10 PID would that be better - but not having tried it I am happy to hear this may not be the case - just wondered if anybody had tried it.

Cheers

 

[Ghillie]

Hi, I think the OPs point and mine is that when the heater kicks in and the stat reaches temp then the heater turns off there is a lot of residual heat so the temp maybe keeps on rising so then the cooling kicks in and so on.

I take your point and I was thinking for the sake of £10 PID would that be better - but not having tried it I am happy to hear this may not be the case - just wondered if anybody had tried it.

Cheers

There's not much residual heat, certainly not when talking relative to the volume of liquid. Remember that a liquid medium such as 23L of wort really needs a lot of energy to heat or cool it. This happens over quite a while also.

With the dS set at a minimum of 0.5C, you won't see any issues. I've yet to see overshoot either. This is why I'm quite confused. With a dS of 0, I can forsee issues of course - but that's obvious.

I understand your thoughts, and before I built mine I did think something similar for a very short while. Try without the PID and see how you go. I'm sure you'll realise there's no issue and save a tenner. Should you somehow find mad temperature swings and other aspects of craziness going on, then you could always buy a PID to fix whatever may be amiss?

 

[David Woods]

Will do and thanks - was trying to prepare for the winter brews as it's just cooling at the moment.

 

[Ghillie]

Will do and thanks - was trying to prepare for the winter brews as it's just cooling at the moment.

FYI I have kept a stable 20C with one of those 60W tube heaters at -10C ambient. They really are such a good heat source.