Low Voltage Thermostat Terminal Designations G RC RH W Y System Switching Heat-Cool-Off Fan Switching Auto-On Automatic Changeover No Dual Transformer Compatible Yes Power Method Hardwired Voltage 20 to 30V AC 750mV Compatible Yes Mounting Horizontal or Vertical Height 5 in Width 3 1/4 in Depth 1 5/16 in Color White Control Range 50 Degrees to 90 Degrees F Features Mercury Free For Use With Gas Oil Electric Heat and Cool System