Based on a number of excellent suggestions I got in previous thread, I have decided to convert all my smart home devices over to ZigBee. I have about 50 switches and sensors on-order at the moment.
One thing I can’t seem to find is a controller for my pellet stove. My stove is installed in my workshop, and during the winter, I usually have to run out to the shop in the morning, turn the stove on, then wait for a hour or two for it to warm up.
I’m thinking that I’ll most likely need to build a controller for the stove. I had some issues with the mainboard in the stove last year, so I’m fairly familiar with how it works. There area few sensors and relays.
- An on/off sensor for the lid.
- A safety sensor for the hopper (makes sure flames aren’t feeding back into the hopper).
- A pressure sensor to detect if the door is open.
- An external temperature probe.
- An internal temperature probe.
- A relay for the igniter.
- A relay for the motor that rotates the hopper.
- A relay for the induction fan.
- A relay for the fan that blows warm air out from the stove.
- A potentiometer that switches the stove on and controls the temperature set point.
I have built a number of custom PCBs in the past, and I’m confident that I could build a replacement for the mainboard that includes a ZigBee radio. This requires a significant amount of design work for the PCB, programming for the microcontroller, etc. I’m also just now learning about how the ZigBee protocol works, so there would be a fair amount of research involved.
My other idea was to build a PCB that essentially acts as a programmable potentiometer, replace the pellet stove’s pot with this PCB, and leave the mainboard as-is.
Has anyone here tried integrating a pellet stove into your home automation? How did you do it?
UPDATE: This was actually very easy. The potentiometer that controls my stove acts as a voltage divider. At 5V, it signals the stove to shut off, and at 0V, it’s fully on. I just leave the potentiometer in the “off” position, and I added a zigbee relay in normally-closed mode in series with the wire feeding from the center. When the relay is “off,” the stove sees 5V and does its normal shutdown routine. With the relay “on,” the stove starts up. HA switches it based on temperature from a temperature sensor in the room. Depending on your stove, you might need a pull-down resistor (if it expects GND instead of an open), but it works perfectly for me.
I really do wish I had paid the extra money and got a stove with a built-in WiFi controller. I looked into ordering a replacement board for a model that is WiFi enabled and retrofitting it into mine, but even within the same brand, the interface and the physical hardware in the stove is different. When I bought my stove, I was more concerned with not freezing to death, and I didn’t really think much about how I’d be using it in the future. Live and learn, I guess.