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Thread: Heat Pump Thermostat Wiring.

  1. #1

    Default Heat Pump Thermostat Wiring.

    Actually I have two questions but will post the other separately. I do a huge amount of repair and maintenance work. Every time I get involved in HVAC sytems and have to wire up a thermostat I get lost. The system I"m currently working on is a new Rheem heat pump. Wires coming from the package unit are pretty standard... red, yellow, green, blue, brown, white(with black stripe). There are 8 terminals in the thermostat (White-Rogers 1F89-211). In general I'm following color codes but am confused as to where the blue and brown wires go although I know the brown is the common for the transformer. The terminals in the thermostat are marked O/B Y G W2 E C L R ... so... which wire goes where????

  2. #2
    Plumber jimbo's Avatar
    Join Date
    Aug 2004
    San Diego


    You have to wire by function. One thing to watch out for...Rheem units have the reversing valve energized on HEAT where many other brands have the reversing valve energized on COOL. This will result in differences involving the B and O wires, usually. You need to take the manual for your T-stat and match the wiring to the diagram for the Rheem unit.

  3. #3


    It took mostly studying and deduction to figure it out. Plus I found a site by doing a google search that explained thermostat control wiring pretty decently. The brown wire on this unit is for common from the transformer which was attached to the "c" terminal of the thermostat and the blue wire is for the heat energizer(reversing valve) which is connected to the O/B terminal...all others were simply color coded.... I've wired up several thermostats and have not done it frequently enough to remember the function of each wire. I'm still learning. Before switching the unit on I had a HVAC pro to check everything out. Only thing I had not done was to put the o/b switch in the correct position...he flipped the switch and that's all. It worked perfectly. Nothing in the product manual/information tells which position the switch is supposed to be in...at least, not in layman's terms.


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