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Thread: Honeywell + Lennox > Nest 3rd gen

  1. #1
    Junior Member

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    Honeywell + Lennox > Nest 3rd gen

    Hello,

    Newbie here trying to switch out my Honeywell VisionPro 8000 to a Nest 3rd generation. It looks like I have a conventional system. One HVAC with 3 zones for each floor of the house. HVAC make is a Lennox, I believe one of the elite series. I have attached a photo of my wires and the terminal guide located in the Honeywell instruction manual as well.

    Based on Nest compatibility online and after speaking to one of their reps, it looks like I am compatible. However, neither they nor I are sure what the U1 wires do. Does anyone have any thoughts? Should I attempt to do this myself or do the U1 wires complicate matters and,Click image for larger version. 

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ID:	1184 therefore, perhaps I should look into hiring a Nest Pro (would rather save the $$ to be honest)?




    Thank you kindly!

  2. #2
    Administrator

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    The U1 wires are used for a humidifier, dehumidifier or a stage of cooling or heating. If you do not know what is connected to these wires you will need to trace out the wire to find out where they are connected to or call a HVAC technician.

  3. #3
    Junior Member

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    Quote Originally Posted by Thermostat View Post
    The U1 wires are used for a humidifier, dehumidifier or a stage of cooling or heating. If you do not know what is connected to these wires you will need to trace out the wire to find out where they are connected to or call a HVAC technician.
    Although I can see a humidity reading, I cannot control it.. so I can only assume that I do not have a humidifier/dehumidifier and those wires must be for a stage of cooling or heating (as the terminal guide and you said). I spoke to Nest support today and, in light of this, they recommended simply disconnecting the U1 wires and taping them. Seems a little strange to me to just disconnect wires without knowing exactly what they do, don't you think? I set up a free "orientation" with the company that installed the HVAC so hopefully they'll be able to give me some insight.

    If anyone has any other thoughts, I would really appreciate it. Thank you!

  4. #4
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    I have the same problemClick image for larger version. 

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ID:	1225. The only difference is that I have three wires attached to the U1 terminals: black and brown to the lower U1, and orange to the upper one. Did you get any solution?

  5. #5
    Junior Member

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    Quote Originally Posted by myrtillerose View Post
    Although I can see a humidity reading, I cannot control it.. so I can only assume that I do not have a humidifier/dehumidifier and those wires must be for a stage of cooling or heating (as the terminal guide and you said). I spoke to Nest support today and, in light of this, they recommended simply disconnecting the U1 wires and taping them. Seems a little strange to me to just disconnect wires without knowing exactly what they do, don't you think? I set up a free "orientation" with the company that installed the HVAC so hopefully they'll be able to give me some insight.

    If anyone has any other thoughts, I would really appreciate it. Thank you!
    Did the hvac company come back with an answer?

  6. #6
    Junior Member

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    I need help with this issue. I want to install my nest thermostat, but I don't know what to do with these U1 wires. Did you get any solution?

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