Please verify that the circuit can handle the amount of amperage your heating system requires. Your thermostat can only handle up to 15 amps so if you are connecting multiple heaters to one thermostat location, you may need to use a relay and a larger breaker. Your or your electrician can find out the amperage rating of your specific floor heating system in installation manual or printed on the box. Note: Just because the Warmup thermostats are dual voltage, this does not mean you can supply any voltage to your heating system. You must supply the voltage supplied to the voltage of your specific heater.