Can I use one thermostat to control multiple Foil Heaters ?
Foil Heating System
Yes, but all heaters being controlled by thermostat must be installed within the same room/zone.
Each thermostat can control up to 16 amps of heating and maximum of two heaters can be wired directly into the back of the thermostat.
If installing more than two heaters connect in parallel via a junction box.
Check out the Foil Heater installation video where this topic is referenced: