I'd quite like to do this for my DVS. I have it on a timer, but I'd like to shut it off below a given temperature.
I might even try to daisy chain them somehow. I always want the DVS on between say 11am and 2pm regardless of the temperature, but between 9am and 5pm I want it on if the temperature is over say 15 degrees.
I'd consider making it myself, though while I have theoretical knowledge I'm not 100% confident in my ability working with mains voltages.