Aprilaire 700 humidifier with Nest thermostat

Discussion in 'HVAC Heating & Cooling' started by DodgeRamFan57, Feb 9, 2017.

  1. DodgeRamFan57

    DodgeRamFan57 New Member

    Joined:
    Dec 29, 2016
    Location:
    New Jersey
    I just got an Aprilaire 700 automatic humidifier for my Arcoaire N9MSB that has a 24VAC connection for a humidifier. I cannot find a wiring diagram on controlling the humidity with the Nest. I've found them using the provided transformer Aprilaire provided. I should be able to bypass using that and have the humidifier trigger off the furnace board. Or am I better off just letting the Aprilaire humidistat control everything?
     
  2. Stuff

    Stuff Well-Known Member

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  4. DodgeRamFan57

    DodgeRamFan57 New Member

    Joined:
    Dec 29, 2016
    Location:
    New Jersey
    Yes, I did see that already. I'm just confused on the wiring of the humidifier with trying to integrate the Nest so that it triggers the humidifier to run.
     
  5. Stuff

    Stuff Well-Known Member

    Joined:
    Mar 7, 2013
    Location:
    Pennsylvania
    Nest says that you can control the humidifier valve directly by connecting one lead to C and one to *. Most of us recommend putting in a relay, though. Your furnace control board (https://www.questargas.com/ForEmplo...g/Furnaces/Day&Night N9MSE N9MSB A SERIES.pdf) has both a 120v HUM terminal as well as a HUM 24vAC. You would use the 24vac one. The HUM terminals should only be powered when the furnace is running and heating. See diagram from one of Amazon's reviews.


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  6. DodgeRamFan57

    DodgeRamFan57 New Member

    Joined:
    Dec 29, 2016
    Location:
    New Jersey
    Yeah, it's probably not worth the effort. The Aprilaire is an automatic control model that monitors from the return line so its probably easiest to just use the provided controller.
     
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