See the diagram below for the role of each wire in your system: S - Indoor and Outdoor Wired Sensors Y - Compressor Stage 1 (Cooling) Y2 - Compressor Stage 2 (Cooling) G - Fan C - Common U - Humidifier, Dehumidifier, or Ventilator control L/A - A - Input for heat pump fault O/B - Reversing valve for Heat Pump systems E.. The heat pump wiring diagram shows the wiring colors to attach to each terminal. This is the most common wiring setup for a standard heat pump.. 2 Stage Heat Pump Thermostat Wiring. If your heat pump is a 2 stage model, meaning it has low and high Heat and Cool modes, then you'll need a 2 stage thermostat..
Gas Electric Furnace Thermostat Wiring Diagrams Color Code This complete 24 volt thermostat wiring guide covers all thermostat wiring issues from the simple to the complex - from basic 2 wire thermostat wiring common to gas furnaces all the way to 8 wire thermostat wiring for two stage heat pumps and similar hvac systems. This page includes a heat pump thermostat color code wiring diagram to.. Consult the heat pump wiring diagram schematic to view the complete system connection details. Two-Stage Heat Pump Thermostat Wiring. The wiring process for two-stage heat pumps requires additional complexity. The utilization of two heating or cooling levels in two-stage systems allows enhanced temperature control with better energy efficiency.