WiFi Thermostat with weekly scheduler

The WiFi SSR board project changed a bit and I use classical relays instead of SSRs now. The reason is that SSRs tend to get quite hot when switching larger loads, and the 8A relays I last used actually could be used for max 2.5A load switching with no heat sink. The high quality relays I now use allow 10A load switching and are rather quiet. I also changed the design a bit so that it would fit in a box (DIN rail compatible) for increased safety.

WiFi Thermostat with weekly scheduler

The board now looks like this: (this particular project needs only one relay):

As additional feature, I’ve added thermostat function based on Trystan Lea’s Open Thermostat Scheduler, only my code runs entirely off the ESP8266 SoC. The UI is touch-friendly and works great on mobile devices:

I’ve also added broadcasting functionality, allowing the board to send its state to third party services like emoncms.org and thingspeak.com. The benefit of this is that the board can now fetch historical readings from the services and render some fancy charts for further business intelligence:

The first board went into use for a radiator thermostat project for a downtown place I use as office. The building has central heating and the radiators had manual actuators. I replaced these with a Swiss made thermoelectric actuator that is controlled by the relay and set a heating schedule for it:

I have it running for a week now and am loving the convenience and ability to remotely control the temperature.

The same approach could be used to start heater element in a boiler for example.

I plan to blog about location based switching using owntracks, MQTTand the WiFi thermostat sometime soon.

I’ve set up a WiKi for the project in preparation to having few for sale sometime mid-March 2015.


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