Fridge doesn't start (EDIT: now running but confused)


#1

Hello everyone,

I’ve just ended my setup and I tried to set the fridge in constant mode and it seems that it’s not triggered by the script.

Devices configuration was done smoothly.

While in hardware test mode, fridge can be triggered but stops after a minute. Heating is working fine.

Both are connected to 10A SSR.

Here is the log. If anyone can help me pointing out the issue. It should certainly be obvious but not to my beginner’s eyes :wink:

Many thanks

“kind”: “Pid”,
“name”: “beer2fridgepid”,
“enabled”: false,
“input”: {
“kind”: “SensorSetPointPair”,
“sensor”: {
“kind”: “TempSensorDelegate”,
“name”: “beer1”,
“delegate”: {
“kind”: “OneWireTempSensor”,
“value”: 21.875,
“connected”: true,
“address”: “28FF19578516036A”,
“calibrationOffset”: 0
}
},
“setPoint”: {
“kind”: “SetPointSimple”,
“name”: “beer1set”,
“value”: null
}
},
“output”: {
“kind”: “ActuatorOffset”,
“target”: {
“kind”: “SensorSetPointPair”,
“sensor”: {
“kind”: “TempSensorFallback”,
“onBackupSensor”: false,
“sensor”: {
“kind”: “TempSensorDelegate”,
“name”: “fridge”,
“delegate”: {
“kind”: “OneWireTempSensor”,
“value”: 20.3125,
“connected”: true,
“address”: “28FF205B8516030F”,
“calibrationOffset”: 0
}
}
},
“setPoint”: {
“kind”: “SetPointSimple”,
“name”: “fridgeset”,
“value”: 6
}
},
“reference”: {
“kind”: “SensorSetPointPair”,
“sensor”: {
“kind”: “TempSensorDelegate”,
“name”: “beer1”,
“delegate”: {
“kind”: “OneWireTempSensor”,
“value”: 21.875,
“connected”: true,
“address”: “28FF19578516036A”,
“calibrationOffset”: 0
}
},
“setPoint”: {
“kind”: “SetPointSimple”,
“name”: “beer1set”,
“value”: null
}
},
“useReferenceValue”: false,
“setting”: 2.8125,
“achieved”: null,
“minimum”: -10,
“maximum”: 10
},
“inputError”: null,
“Kp”: 2,
“Ti”: 7200,
“Td”: 1200,
“p”: 0,
“i”: 0,
“d”: 0,
“actuatorIsNegative”: false

EDIT : 09:51 PM: I restarted Pi and controller and now fridge is running. What could this be due to? :face_with_raised_eyebrow:


#2

The fridge is only triggered when:

  1. the cooling PID output (which is the % time of the PWM cycle that the fridge will be on) is higher than the output of the heating PID (same interpretation), and
  2. it has been at least (by default) 30 minutes since it switched from the heating cycle PID to the cooling PID.

My guess is that the fridge wasn’t turning on because either a) the algorithm didn’t think it was necessary (a la option 1 from above–the heating PID output is higher than the cooling PID output), or b) the heating PID was active before and it’s now waiting 30 minutes before activating the cooling PID. It was helpful for me to watch some youtube videos and read some articles on how PID control algorithms work to gain intuition for how my brewpi system worked.

It could be something else, but without more information (ideally screenshots of the graphs from the brewpi UI) it’s difficult to diagnose the problem.


#3

Thanks for the details :wink: I understand better how it behaves!

My guess is that I didn’t wait enough for the fridge to start. It seems I was a bit impatient to see it working…