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  1. #1
    Join Date
    Apr 2013
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    Visionpro IAQ not keeping any form of stable % of humidity

    Hi all, I'm hoping someone can help. I moved into my home about 2 years ago in Las Vegas, where the humidity is pretty much non existant. One of the first things I did was have a whole house humidifier installed (Aprilaire 800 Steam Humidifier) and the thermostat replaced with a Honeywell IAQ. Every since then, no matter what setting I put the IAQ to, even AUTO/60% which is its max, my house ends up in between 20-32% humidity. My goal is about 40-45% due to some of the hardwood I installed (has already been destroyed once when the aprilaire's main circuit board fried itself, was dead for two weeks and I wasn't home). My HVAC guy couldn't figure out what the issue was so he offered to try putting the Aprilaire's humidistat in line with the honeywell, thinking that if the honeywell doesn't make a call for humidity for some reason, the Aprilaire's humidistat would as it operates more independent. That actually worked pretty well, until the humidistat stopped working (its now dead and Aprilaire won't replace it even though its under warranty), set the humidifier to run at max full time and I ended up with an A/C unit that was literally dripping water out of the ducting.

    So, what I am trying to figure out is with the equipment I have, is it possible to get a stable 40-45% humidity in the house and if so, what am I doing wrong? As a last ditch effort I just disabled the outdoor temp sensor thinking the IAQ is doing some calculations or something. I'm pretty desperate at this point and have even purchased 2 free standing whole house humidifiers (put them in opposite sides of the house) and try to keep their tanks full trying to keep the % right but they run out of water so often that it doesn't really help.

    My second question is that from what I am reading the IAQ will only make a call for humidity when its heating, and NOT when its cooling. That obviously is a pretty big problem when I live in the desert and its usually fairly hot outside...

    Thanks for any assistance!

  2. #2
    Join Date
    May 2000
    Indianapolis, IN, USA
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    It will humidify with fan on but since it is pretty rare to need humidification while cooling, not sure it will run the humidifier with cooling. Could be wrong. You'd certainly not want the outdoor sensor looking at things, it would shut the humidifier down when it gets warm out.

  3. #3
    Join Date
    Jan 2008
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    You do realize your cooling system is a whole house DE-HUMIDIFIER, right?
    "Hey Lama, hey, how about a little something, you know, for the effort." And he says, "there won't be any money, but when you die, on your deathbed, you will receive total consciousness." So I got that goin' for me, which is nice. - Carl Spackler

  4. #4
    Join Date
    Aug 2004
    North Richland Hills, Texas
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    You can humidify during calls for heat, and humidify with fan only, but the IAQ thermostat will not run a humidifier during calls for cooling.
    A steam humidifier should never be operating during calls for cooling, or you will have condensation in the duct system.
    Your wood floors and furnishings don't need 40% RH anyway.

    I'd also look into getting a blower door test done on the house to determine the extent and location of leakage. You may be able to stabilize the house, and greatly reduce the need for humidification, by stopping excess infiltration.
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  5. #5
    Join Date
    Jan 2004
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    As far as I know, the IAQ won't humidify until it has made a heat call, even in fan "on" mode. Use a separate humidistat, not the IAQ.
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  6. #6
    Join Date
    Sep 2002
    Northeast Ohio
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    Sounds like a job for "Swamp Cooler Man". Two pieces of equipment fighting each other for the most part. "I want it in!" "Well, I want it out!". 40-50%? Not likely with the set up you have now.
    A good HVAC tech knows how, an educated HVAC tech knows why!


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