Glycol chilled conical setup

Hardware
1

Hi - I have a legacy BrewPi setup with an Arduino that has served me well for ~5 years controlling a hacked freezer with the fermenter inside. I have recently upgraded to a conical with a heater and a Peenguin Glycol system and wasn’t happy with the control I was getting from the bundled Inkbird controller so I decided to revive my trusty BrewPi.

It has been running for a couple of batches now and the control is great. The heater is Spike’s heater tape under a neoprene insulating jacket and the cooler controls the pump from the Glycol reservoir. The Penguin chiller controller just maintains the glycol bath at 28 degrees for the pump to use when the BrewPi calls for it. As I said, it works great - far better than the Inkbird controller.

The question I have is that I just realized that the ‘conventional’ fermentation chamber design I originally used had two temperature probes. One for the wort temp and one for the ambient chamber temp. That chamber temperature probe is just laying on the counter basically reading ambient room temp. Should I just disable that sensor in the Maintenance panel, put that sensor under the neoprene jacket on the outside of the fermenter, or just disconnect it?

Also the settings I am using are:
Kp=6
Ki=0.2
Kd=1.5
I get about a 2.7 degree F swing when the glycol pump kicks on - probably because it is so efficient in cooling using Spike’s TC-100 Temperature control coil in the wort. Are there better settings I should be using?

Thanks,

Paul

2

The Arduino version of BrewPi doesn’t really have good support for glycol.
It was not designed to work without a fridge temperature, only indirect control through the fridge temp.
And the fridge temp control with BrewPi is hardcoded to use on/off control with some overshoot estimation.

With our Brewblox software on the Spark, we have PID + PWM control of the glycol pump and can turn it on for say 15 seconds every 5 minutes. With Brewblox, you should be able to get a 0.2F swing instead of 2.7F.

If you want to find a hack and use the old BrewPi algorithm, you’ll want to measure a ‘fridge’ temp that responds quicker to the glycol than your beer.

3

Thanks Elco! I put the ‘Fridge Temperature’ probe under the insulation of the glycol line to the fermenter chiller. I am getting a lot better temperature control vs when I just had it hanging and measuring room ambient.

Thanks for a great product and the support,

Paul

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