MySensors controlled heating
I have made a node which measures the temperature using a DS18b20 and controls an electric heating valve (http://www.ebay.de/itm/350991304709?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT) using a MOC3023 optocoupler with triac output (little white chip, works like a solid state relay. Only for small currents, but very cheap). The power supply is the pcb of a usb power supply.
The code is a simple combination of the ds18b20 and the relay actuator examples.
Using openHAB I can set a target temperature. When the temperature is below the target temperature the valve is opened. Else the valve is closed. Since I am using a NC (normally closed) valve, the valve opens when connected to power.
Interesting stuff. I have similar valves and thermostats to control them. It's an older floor heating system where the thermostats are starting to fail. I've been thinking of doing something similar since the thermostats, even ugly ones with just a dial and no lcd cost $50 a piece or something. It really starts to add up after a couple of floors.