Lennox Mercury to Nest

Discussion in 'HVAC' started by frankstallone, Feb 2, 2018.

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  1. Feb 2, 2018 #1

    frankstallone

    frankstallone

    frankstallone

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    Bought a home with a nice HVAC setup. Everything is fairly new expect, what looks like, the original Lennox mercury based thermostats. I wanted to replace them with Nest Thermostats and have, but I am not 100% sure I got it right. Let me tell you what I have, upload some photos, and let me know what you think. I confirmed with Nest that their thermostats will work with the setup I have. Also if you think there's a better place for me to post this question, feel free to reach out and let me know.

    * HVAC Setup *

    ** Larger Unit **

    LENNOX ELITE XP13-036-230 - 3 TON, UP TO 14.2 SEER / 8.5 HSPF, 208 / 230 VOLT, SINGLE PHASE, R410A HEAT PUMP.
    CBX27UH-042, Upflow/Horizontal, Air Handler, Multi-Speed, 3.5 Ton, Elite Series

    ** Small Unit **

    LENNOX ELITE XP13-024-230, Heat Pump, 13 SEER, 2 Ton, R-410A, Elite Series.
    CBX27UH-030, Upflow/Horizontal, Air Handler, Multi-Speed, 2.5 Ton, Elite Series.

    The Lennox thermostats have _no_ model numbers. The best I could find was a sticker with LR1620 on it but Google only finds Honeywell thermostats with that number. Calling Lennox was no help. They told me to call a Lennox Certified Dealer.

    Both thermostats have the same wires run to them (this is at the furnace):

    ** @ Furnaces **

    R - RED,
    R - ORANGE,
    G - GREEN,
    C - BROWN,
    Y1 - WHITE,
    W1 - YELLOW,
    O - BLUE

    Then there is another wiring loom that goes to the same motherboard out to the heat pumps. For instance, R is jumped to the RED cable that goes outside.

    ** @ Nest thermostat **

    Y1 - YELLOW,
    G - GREEN,
    OB - BLUE,
    RC - RED,
    W2 - WHITE
    C - BROWN

    ** Photos of Thermostats **

    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
     
  2. Feb 2, 2018 #2

    frankstallone

    frankstallone

    frankstallone

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    ** Photos of 2 Ton Units **

    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
     
  3. Feb 2, 2018 #3

    frankstallone

    frankstallone

    frankstallone

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    ** Photos of 2 Ton Units (Continued)**

    [​IMG]

    -- This last photo I am holding the loom going to the thermostat

    ** Photos of 3.5 Ton Units **

    [​IMG]

    -- Only one photo because they're mostly the same, wiring wise.
     
  4. Feb 3, 2018 #4

    slownsteady

    slownsteady

    slownsteady

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    I'm 98% sure that is a honeywell tstat just branded by lennox, so i would be pretty confident on the info you can find in the Honeywell owner's manual.
    As for the Nest Tstats, I'm not qualified to answer.
     
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  5. Feb 6, 2018 #5

    frankstallone

    frankstallone

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    Thanks slownsteady! I was able to get outside and get the wiring from out there. Both units have the same wiring:

    ** 2 Ton XP13-024-230-03 **
    ** 3.5 Ton XP13-036-230-03 **

    W1 - White
    C - Black
    R - Red
    O - Blue
    Y1 - Yellow
     

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