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  1. #1
    Join Date
    Jun 2008
    Posts
    2

    Default Heat Pump Thermostat Help!

    I'm in need of some HVAC help on replacing my old non-programmable heat pump thermostat. I only use the heat pump for AC in the summer. It's used as a backup in the winter in case the oil furnace goes out.

    I bought two different Honeywell thermostats. The first one I bought was because it was on sale for about $10 & I didn't realize I had a heat pump at that point. The second is specifically for a heat pump setup.

    The problem I have is neither of the new thermostats have the same connections as the old one & I don't know where to connect 2 of the wires. Any help would be appreciated.

    Original Thermostat

    In the winter months the mode is set to heat & the system is set to Emergency Heat to run the furnace.




    Honeywell Heat Pump Thermostat

    As you can see there is no place to connect W3.
    Can O & W be connected to the same place?




    Reg. Honeywell Thermostat

    missing more connections than the other thermostat is.

  2. #2
    Join Date
    Aug 2007
    Location
    The Great White North
    Posts
    4,045

    Default Re: Heat Pump Thermostat Help!

    Below is what seems to be your current wire deignation.
    It sounds as though you have a duel fuel type heating system .... heat pump / oil furnace. Your current thermostat has a 3rd heat control line .... the new one only has 2.

    From what I can tell hooking the " O " and "W" wires together would be a bad idea.
    The " O " wire is for the reversing valve for the cooling and the "W " is for the heat .... so hooking the 2 wires together sounds like it would have cooling and heating happening at the same time.

    I'm no means an expert on heat pumps but it sounds like you might want to check with a HVAC contractor.




    Standard Terminal
    Designation


    B - Heating damper motor; changeover valve
    E - K Emergency heat relay
    G - F Fan relay coil
    L - System monitor
    O - Cooling damper motor; changeover valve
    R - Power connection to transformer (internally connected for heating
    and cooling)
    RC - Power connection to cooling transformer
    RH - Power connection to heating transformer
    W1 - H1, R3 Stage 1 heating control
    W2 - H2, Y, R4 Stage 2 heating control
    W3 - Stage 3 heating control (b)


    (a) - Other terminal designations can be used that are not listed on this table. Refer to the hookup drawing and internal schematic for exact connections.


    (b) - W3 controls the auxiliary heat like W2, and allows adding additional stages of auxiliary heat with outdoor thermo stats while maintaining the proper second stage anticipation.
    "" an ounce of perception -- a pound of obscure "
    - Rush

  3. #3
    Join Date
    Jun 2008
    Posts
    2

    Default Re: Heat Pump Thermostat Help!

    Thanks for the info!

    It is definitely at dual heat system. The heat pump was installed by the previous owners in the 80's as part of a government rebate program to switch to electric heat. The oil furnace is intended as a backup, however I use it the other way around. What with the price of oil these days though I may want to re-examine that plan.

    Guess now I'll need to get some professional help ... and get somebody to look at the HVAC system as well.

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