Schluter® DITRA-HEAT-E-RR POWER MODULE WHITEThe E RR power module lets you expand a heated floor zone beyond a single thermostat's 15A limit. It installs like a second thermostat but takes its signal from your existing DITRA HEAT thermostat one control point, multiple cable circuits. Connects to any DITRA HEAT thermostat (E R, E RT, E WiFi, E RS1) via a low voltage 20 AWG signal wire when the thermostat calls for heat, the E RR fires its cable circuit simultaneously Each E RR handles one