Garage door opener.
On "master" side take apart remote and wire the NO side of the relay where the button goes. Thermistat operates relay, contacts close, same as pushing button, and radio signal is sent.
On "slave" side take apart opener, and find the power leads to the motor. Wire relay in there. Radio signal is recieved, brain feeds power to where motor used to be, relay is closed.
* I haven't taken apart a door opener, but I suspect the "slave" relay is already there, as I'd bet that they don't run the motor operating current through whatever PCB controls the radio.
** You'll have to fiddle with the limit switches to get it to shut off in a way appropriate to your application.