we made a very basic circuit, with a relay switching on 12V starting the chaudiere (furnace).
of course now we can start making crazy contraptions controlling the temperature in the space. (anybody on having an IPv6-only control of the room-temp :-)
ahaa --- that's a reason to get you all to switch to IPv6, no ? :-)
all thermometer controlled ic-s you could want [maxim thermo ic's]
 Good candidates
The clock IC is interesting, because you can set up a heating schedule and have the thermostat working alone.