thermostat

A customized thermostat for my USA central heating system.

There's a lot of bugs here. I wrote down the ones I remember, but I'm certain there are more that I don't remember. Build at your own risk! I have been using this thing for myself with no problems (after initial bring-up) for over a year though.

Bugs & notes

There's a provision for a microphone. The idea was to FFT the audio from the system running to determine if there is a problem. Turns out in practice my ears work just fine for this, and I didn't bother implementing this in ESPHome.

There's two different onboard temperature sensors. I ended up using this entirely inside a closet, so I didn't populate and test these sensors. I instead soldered on a cable running to an exteral I2C temperature sensor.

I never figured out how to automatically zero the pressure sensor. In practice, this is not a problem since I can look at the graph in HomeAssistant every few months and manually subtract the zero point.

DC-DC converter gets pretty hot. I don't remember if this was a serious problem or not, but I put a heatsink onto it anyway.

There's no mounting holes or corner fillets on the PCB. This makes it challenging to install into an enclosure.

Features

• filter change measurement (differential pressure sensor)
• temperature sensor
• ESP32/ESPHome controlled

Project outline

• thermostat.kicad_pro: the kicad project with the PCB
• enclosure/: a snap-fit enclosure for the provided PCB
• esphome.yaml: an example ESPHome config