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Heat pump interface/ wire saver

Does anyone know if an interface/wire saver is available to use in a air conditioning to heat pump installation? We are replacing an air conditioner with propane furnace, to a heat pump with propane furnace back up, and currently have only two control wires going to the air conditioner. I was hoping that something is available, similar to what is available for thermostats, that can be installed and avoid having to pull 18/8 wire form the attic to the heat pump location. thanks to all


  • Jamie Hall
    Jamie Hall Member Posts: 21,093
    Almost certainly not. A "wire saver" is for use when the new thermostat needs a constant power supply but is otherwise just on or off -- but your new application and control device (calling it a thermostat is pretty simplistic) needs more independent wires to tell the heat pump whether to heat or cool (and likely, whether high or low) and to call the backup furnace when wanted. Plus power for the control device.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • mattmia2
    mattmia2 Member Posts: 7,708
    Doesn't tekmar(and a few others) have some thermostats with a control head that is installed with an existing 2 wire cable with the control relays back at the equipment?
  • ratio
    ratio Member Posts: 3,402
    Honeywell 8000 series can operate an EIM wirelessly & use the existing wires for power alone. Works good, & you'll gain the capability of using wireless averaging sensors.
  • mattmia2
    mattmia2 Member Posts: 7,708
    Oh, i misread. You need something at the outdoor unit. That may be more challenging. Tekmar or honeywell may still have something. You could also possibly depending on the exact setup be able to put a split type thermostat somewhere near the outdoor unit and run new or reuse existing wiring from that location.