The thermostat controls the complete operation of a heat pump system installed with optional strip heat. Thermostat manufacturer algorithms determine the optimal timing and intervals for the heat pump, the heat stages if applicable to your model, the strip heat and the indoor fan speed. Control settings for your system are located in the thermostat setup menu, accessed by keystrokes determined by the specific thermostat model. Settings information is found in the heat pump and strip heat installation instructions.
Things You'll Need
Plastic zip ties
Pull certified, UL-listed low volt wire from the outdoor heat pump to the indoor air handler. Secure the wire along the refrigerant lines leading from the heat pump to the air handler using plastic zip ties. Bring the wire into the low volt control box of the air handler.
Pull a low volt wire from the strip heater to the air handler control box. The strip heat is mounted on or near the air handler in the supply ductwork, requiring only a short amount of wire for connection. Secure it to the electrical conduit with zip ties, or secure wire
Pull the low volt thermostat wire from the thermostat to the air handler. Follow plumbing or electrical lines as needed to route the wire safely and efficiently to the air handler control box. Secure the wire using methods acceptable to your local building codes.
Connect each of the low volt wires according to the thermostat, heat pump and strip heat instructions. Typically, the Y and Y1 terminals from the thermostat control the heat pump compressor operation. The W and W1 terminals from the thermostat control the supplemental heaters, such as the strip heat. The O terminal controls the heating or cooling mode of the heat pump. The G terminal controls the indoor fan operation of the air handler.
Secure the wires as indicated in the air handler instructions. Most manufacturers provide wiring terminal strips with the appropriate letter designations to aid in wiring. Strip 1/4 inch of insulation from each wire with the wire strippers. Secure each wire to the appropriate screw terminal with the screwdriver. Test the heat pump and strip heat in all modes after installation to ensure proper operation.
Low voltage wiring connections from the thermostat, the outdoor heat pump unit, the air handler and the strip heater are usually made inside the air handler. All the low volt wires in questions are brought in to one of the air handler's control boxes to ease installation and future troubleshooting procedures.
An incorrectly or improperly wired low-voltage system can permanently damage the electrical components of your heat pump system. Make sure the electrical circuits to the heat pump, the strip heat and the air handler are all off. Heat pump systems often have several electrical circuits feeding all the various components.