How to adjust for a more agressive cooling cycle?

Troubleshooting
1

I’ve had my BrewPi Spark for about a month now and absolutely love it, but I feel I can do better with adjusting for my fermentation chamber. My first brew was a mid 60sF ale, and since it’s summer it wasn’t very hard for the BrewPi to maintain the temp properly, so it worked flawlessly.

I’m now lagering a second batch and I’m having a little trouble keeping the temp from swinging and the fridge cycling constantly. Obviously, a lot has to do with the fact that it’s trying to maintain 33F when it’s 70F in the room, so it’s going to swing faster and cycle more (fully understood), but it looks like the BrewPi isn’t taking full advantage of the fact that the fridge can cool down to 20F easily and fairly fast. Instead it only goes down to about 25F on average, over and over again, which causes the beer to take much longer to reach temp.

I did set the minimum temp down to 20F, but the algorithm seems to prefer lots of short cycles instead of longer deep cycles. Can you recommend PID settings to get it to cool down to the max of 20F? Sorry, the PID settings are a bit beyond me. :slight_smile: Currently everything is at defaults. Thanks!

cooling.png964×494 47.1 KB

2

What it does is it cools until it expects to land on the setpoint, which it does each time.
But because it warms up quickly afterwards and then has to wait a minimum time, the average is higher.

I am working on PWM actuators with a PID for each actuator, which will eliminate this.

3

Ahh understood, and appreciate the work as always. For now I increased the Kp and it seems to help a bit by cooling longer and deeper, but that definitely sounds like the way to go.