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    lrningtheropes's Avatar
    lrningtheropes Posts: 2, Reputation: 1
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    #1

    Jan 5, 2009, 09:22 PM
    Wiring for Programmable Thermostat
    I'm a single girl and new homeowner, so please bear with me :)

    I currently have a Honeywell dial thermostat, and just received a Honeywell RTH230B programmable thermostat, which says it works for 2-, 3-, 4-, or 5-wire installations.

    When I took the old thermostat off the wall, there were 6 wires: W (white), Y (yellow), G (green), R (red, two wires, but it looked like one was not connected to anything), B (red).

    I have two questions:

    1) Do I need the 2nd R wire (that didn't appear connected)? If so... where would it connect on the new thermostat? Or will the new thermostat not work for me?

    2) All the letters on the wires on the old thermostat match the instructions for the new thermostat, except the B and R wires. Which is heating power supply (Rh in the instructions) and which is cooling power supply (Rc in the instructions)?

    Thanks in advance for any guidance!
    royboy74's Avatar
    royboy74 Posts: 21, Reputation: 1
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    #2

    Jan 6, 2009, 01:31 AM
    OK first what type heat do you have ? Do you have a/c ? Do yopu have a/c with heat pump basic wire red to red I would use the one they used the other may be faded either brown or orange ( g) green (fan) yellow to (y)a/c blue to (c) or common (r) to red and (W) to white more info needed if this did not help
    lrningtheropes's Avatar
    lrningtheropes Posts: 2, Reputation: 1
    New Member
    		  
    #3

    Jan 6, 2009, 06:24 AM
    I have a gas furnace and central air, but I'm not sure if I have a heat pump (how do I tell?)

    How do I know which red wire goes to heat & which to air?
    KISS's Avatar
    KISS Posts: 12,510, Reputation: 839
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    #4

    Jan 6, 2009, 06:37 AM

    I'm worried about three RED wires and also the terminal B.
    "B" may be common, so it would be nice to find the manual online for your current model. Common just allows a thermostat to be powered by the furnace and not batteries.

    Terminal R is normally RED. In your case Rc gets connected to Rh and becomes R.

    So, my question is: What is the actual function of B? It's not standardized.
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