This is the cheapest one out there:
[Link: x10.com]It's not a real thermostat, instead you mount it about 1/2" under your present thermostat and plug it's power supply into an appliance module.
Inside the case there are severial resistors which heat up when the device is turned on, the rising heat fools your thermostat into thinking the room temp is approx. 5-10-0r 15 degrees (set with a switch) hotter than it really is.
You can then control the device with any HA program, (like ActiveHome).
I use one in my apartment, controlled with an Ocelot. The Ocelot determines the season and the day of the week and sets the setback temp accordingly.
In the winter it is turned off in the morning at 0530 until 0730, then is on while I'm at work. and turns off before I come home. It turns on again at night after I've gone to bed.
On the weekend it goes off at 0830 and stays off until midnight.
This way my apartment is cozy when I'm at home and the temp drops about 7 degrees when I'm out or asleep.
In the summer the on /off cycles are reversed to control my air conditioning.
This works for me since I can't change the wiring in my apartment.
This message was edited by ONEAC on 08/26/03 07:42.