I have my refrigerator circuitry bypassed and Brewblox controls the compressor directly. Occasionally, when I have the fridge set point low or during periods of cold crash, the evaporator will ice up. I notice this behavior when the fridge temp starts to rise during a period in which I would expect it to remain steady. I currently correct this by disabling the set point and letting it warm naturally over a period of time, but often forget to re-enable the set point.
Would it be possible to add a setting to configure a periodic time of free-rising temperature? Perhaps the “Digital Actuator” block could have an option to “Pause running every x days/weeks/etc for x hours/days/etc.”?
This can be implemented using the Sequence block: Blocks | Brewblox
Automatically starting a defrost cycle every few weeks would be risky - it’s very easy to forget, and then have it kick in during a cold crash. Safer would be to start the defrost manually, and have the sequence automatically re-enable your actuator X time later.
Some fridges have a defrost heater even, to shorten the time to melt the ice. A fan would also help.
A good idea would be to set up a mutex, so the defrost heater and cooler are never active at the same time.
That’s a safer approach than having the sequence disable the cooler, then enable the heater.
A sequence could wait for the cooler to turn off first, or with a mutex in place just try to turn the heater on and wait for the state to become active.
If you have the hardware figured out and need help with the sequence, let us know.
This is all good input. Thanks @Elco and @Bob_Steers.