Sometimes you have a large area you want to heat, such as a basement, that a single thermostat can't handle.  A power module is necessary if you want to put more than 150 sq. ft. of a 120V floor warming system on one thermostat or 300 sq. ft. of a 240V floor warming system on one thermostat.  The module increases output by 15 amps allowing you to heat larger rooms or additional areas with one thermostat.
Make sure the circuit breaker has enough amperage capacity to power your floor warming system. 
Must be used with OJ Electronics Thermostats
Can be used with 120V or 240V system
Built-in GFCI
Class A GFCI: suitable for wet room installation
Screw terminals for safe and easy installation
You can not connect 120 Volt Systems and 240 Volt Systems on the same thermostat
Low voltage wire is needed to connect the thermostat with the power module. Respect polarity.
3 Year Warranty