Refrigerator
This project started four years ago. I used components from a household refrigerator to convert my icebox into a powered refrigerator. After four years, I had to replace the compressor with a 12V DC model, which I had planned to do from the beginning. So far, everything has worked well with an inexpensive Chinese-made thermostat like this one.
However, I went through three of these thermostats in four years. I think the main problem lies in the sensor and sensing circuit: moisture and vibration seem to make them unreliable. After just a few days, the latest one started showing +26°C when the refrigerator was cold and +2°C when the box was warm. Maybe interference from the AC power lines affected it, but I got tired of fighting this battle.
Welcome to my life ;-) I decided to design my own solution with a 1-Wire digital temperature sensor, remote refrigerator control, a connection to my boat computer, a food safety alarm if the temperature stays above 7°C for too long, and additional compressor protection.
I built the thermostat around an ESP-12F module, which is a great fit for this kind of project.
- Control temperature in the box.
- Control fan inside the box if you have one.
- May control variable speed DC compressor to to boost cool when needed.
- With additional sensors _may_ monitor freezer volume temperature, compressor, condenser, evaporator temperatures and notify you with errors.
- all errors may be disabled if if not needed.
- Main interface is simple as it could be - one button, one RGB LED in the button, buzzer.
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- It provides simple on/off function, mute alarms and check alarm codes when problem happen.
- Indicator shows current state, but likely all of time it will be just blue ;)
- 2 light modes day and night (to dim indicator and do not blind you at night
- Advanced interface (Web interface over WIFI)
- Here you can do everything
- Set temperature
- Assign temperature sensors to functions if you use more than one.
- Set alarm temperatures
- Enable/disable alarms.
- MINOR - keeps cooling (red flash every 5 s)
- 11 Door open - close the door
- 22 Cooler below 0 °C - check set temperature
- 24 Freezer below -25 °C - check the freezer
- 25 Extra sensor lost - check its wiring
- 26 Cooler above 10 °C - check door and load
- 27 Freezer above -5 °C - check door and load
- 31 Compressor hot - check ventilation
- 32 Condenser too hot - check fan and airflow
- 35 Evaporator below -30 °C - check for ice
- FOOD SAFETY - keeps cooling (amber LED)
- 21 Cooler warm 30 min - check food, double-click
- 23 Freezer warm 30 min - check food, double-click
- MAJOR - cooling stopped (steady red LED)
- 51 Not cooling - service needed, then power cycle
- 52 Cooler sensor lost - check sensor, power cycle
- 53 Compressor overheated - cool down, power cycle
- Compressor related settings
- Firmware update over web interface
- Web interface has two modes BASIC and ADVANCED
- MQTT - connection can be used to integrate thermostat to your OpenPlotter infrastructure
- Serial port - for "nice" display, but i think it is overkill
Web interface screen examples
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