Granger also sells Ranco thermostats that can run on 120 or 24 volt and have independent sensors and relays. a 120 V stat can switch a milivlot or 24 volt device or the other way around. $50 or less if you poke around on the price. I use them all over the place. In RTUs, duct air valve control, zone valve control, for tank heaters, freeze control systems and other devices. You can set the differential from one to 30 deg. They are cheap, dead nuts reliable as well as accurate. The sensor line can also be extended. you can also make your settings and flip a little switch inside to prevent tampering by knob monkeys.