Question about Aprilaire 600 Humidifier

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Aprilaire 500 - Everything works, but humidity will not increase!

I've got a brand new home (2 months old).  Had the 500 model installed about a month ago.  I am not using the controller supplied by Aprilaire.  I am using a white-rodgers thermostat that has the ability to control humidifiers.  
Originally, my contractor wired it in a way that the water solenoid would only be powered with a heating call from the t-stat.  I thought everything was working fine as the RH was more or less hovering around my humidity setting of 38%.  It would fluctuate 30-39% daily.  Now thatthe outside temps have dropped to about 20 degrees fahrenheit (-7 celsius) my RH is around 21-26%.  I suspected that the furnace was just too efficient and didn't give the humidifier enough time during cycles to make a significant impact.  So I had my contractor re-wire the system so that the humidifier could run indepedant from the heat call.  The white-rodgers t-stat has a feature in which it can trigger the water solenoid AND the blower together on a separate call.  With the setting still at 38%, and the ambient being 25%, I had it run for a good week with no significant increase.  
I then contacted Aprilaire.  They suggested that I switch the water source from the cold line it was currently connected to, to the hot water line.  The rep I spoke to said that the system needs heat (despite what the owners manual states).  Whether from the furnace or the water, it needs heat.  Had the water lines switched the other day and still no change. 
So as it stands right now, the t-stat has the fan and the water going 24/7 since the humidity level is not being reached.  I have verified that the t-stat does works, the blower fan and humidifier are being triggered, the solenoid is powered and running the water, the water is entering the water panel, and the water is also draining. Just can't get the humidity level up!  My house is brand spanking new.  2170 sq.ft and from what I understand the 500 should have no problems with a house this size.
Can anyone help me out with this?  I am all out of ideas.
Thanks in advance!

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  • Stephen Evans May 11, 2010

    Is the humidifier mounted on the slpy or return duct. also i hate to say it but you should use the aprilaire humidistat, mounted to the duct. It sense humidty much more accuratly that way



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You should take out that aprilaire and throw it in the garbage or return it to who you got it from. Ask them why they didn't offer you the best humidifiers available. The only way to truly control humidity in your home without running your heat is a steam humidifier. Autoflo makes a good one also honeywell makes a new one. I have installed a honeywell tru steam in my own home and a few customers it hasn't lived up to its advertising. The auto flo has never given me any problems with customers.

Posted on Jan 05, 2009


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