The QuietWarmth Power Module for Radiant Floor Heat Systems can be connected to your thermostat to double the area of operation. Power module must be connected to its own dedicated 20Amp circuit. Power module operates as a power relay and cannot be used to independently control temperature of radiant heat mats. Compatible with 120V or 240V systems. You can connect up to 120 sf of 120V mats; or 240 sf of 240V mats per thermostat.