Aprilaire Humidifier Does Not Turn on


Old 01-30-05, 05:20 PM
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Aprilaire Humidifier Does Not Turn on

Humidifier that came in recently purchased house has never turned on. Water gets to the solenoid and when I put the 24VAC across solenoid water comes out the other side (basically solenoid is good and water flows).

When fan is on resistance across current sensing relay is different than when fan is off (65 vs 85)

Resistance across humidistat does not change regardless of dial (manual 4016 humidistat).

It seems as if the humidistat is wasted, but I have some concern about the relay. Would prefer not to go into the air handling unit if I can help.

Any thoughts on how to know more certainly if the humidistat and / or relay are bad?
Old 01-30-05, 05:35 PM
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Do you mean A 50 relay on the blower wires? If so when the blower is on you should have the 110V going to work the humidifier do you get 110V ??? You can also put a jumper across the humidustat with blower on and see what that does. Post back in same post if we can help you more.

Old 01-30-05, 06:29 PM
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Thanks for the quick reply. Couple clarifying things. I have a 560, so the humidifer is running on 24VAC.

The humidistat is before the relay. I shorted out the humidistat like you suggested and the solenoid kicks on/off with the blower. Looks like the humidistat is the culprit.

Thanks again
Old 01-31-05, 07:05 AM
Doug H.
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slightly different problem

I didn't want to start another 'humidifier not working' thread, so I thought I'd add on here. Let me first say that I'm not as savvy as Zeke on anything electrical.

I had to replace the feed tube on my humidifier (Aprilaire 560). After I did so, and turned on the humidistat and blower, no water came out of the output line. I loosened the fitting on the output line, and water jetted out. I re-tightened the fitting, and water then came through to the humidifier.

A couple days later, however, nothing is happening. When I turn the humidistat I hear the small 'click', but nothing else, even when the blower is on. No water is getting through to the output line. I did not try loosening the fitting again. I'm concerned I somehow screwed up the solenoid when I replaced the feed tube. Or might it be something else? I'm fairly sure it's not a problem with the input line or the saddle valve, since water appears to be getting to the solenoid.

Any help/advice appreciated...

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