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HVAC bros - humidifier not working


zeitgeist57

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Need some CR assistance. Whole house HVAC is fine, but humidifier doesn't kick on ever. I tested out the water solenoid with a 9v battery and it opened up. With the heat on this morning, I crossed the 2 wires from the HVAC directly to the water solenoid (bypassing humidistat controller) and nothing happened.

 

Humidifier: Aprilaire Model 4655 (manual controller)

HVAC: Lennox CX34-44/48C-6F-1

Everything was installed new in 2013

 

I thought it might have been the humidifier controller, but now with direct-wiring to the HVAC not activating the solenoid, I'm wondering if the HVAC reset itself and doesn't/won't activate the humidifier. With the weather turning colder and HVAC drying out the air, I'd really like to keep humidity back in the house.

 

Thanks and Happy New Year!

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Clay, I have an AprilAir system as well - don't know the model but I "think" most are similar similar.

 

The system is pretty basic....

1) Power across solenoid and it opens - solenoid OK

2) Check manual "Humidistat" switch - continuity tester across the two wires, turn knob and see if it goes from "infinity" to continuity at some setting (If continuity go to #3 - if not switch is bad or humidity is too high in the house)

3) Check for power to the Humidistat (if no power - go to #4)

4) Mine has a small transformer for power for the Humidifier - check for power at the transformer with HVAC on - if no power it's then likely a problem with the furnace power/wiring not supplying a signal that it is "on".

 

Good Luck!

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4) Mine has a small transformer for power for the Humidifier - check for power at the transformer with HVAC on - if no power it's then likely a problem with the furnace power/wiring not supplying a signal that it is "on".

 

This is actually where I'd go next now that you checked the solenoid. I put on a Honeywell aftermarket box last winter, and it's pretty easy to miss this, especially if it's on a switch somewhere you don't usually think about. Also, check (if it exists) the bypass damper is open, and that the pressure sensing hoses on either side aren't clogged.

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Sooo...I broke out the installation booklets.

1) The wiring from the Humidifier manual control and solenoid were wired up to the terminals on the IFC for the thermostat. The instruction manual showed a spot on the IFC where there was a HUM switch.

2) Further review showed the wiring for a 24V humidifier going through a separate terminal.

3) Wired humidifier manual control as per diagram.

4) Fired up heater and water solenoid kicked on.

5) Turned humidifier down while heater/blower running and solenoid turned off.

 

Didn't realize that the water supply was hot water. Interesting!

 

Is it normal for the solenoid head to be warm to the touch when it's opened? I mean, easy to hold onto so not scorching hot, but warmer than the waterline feeding it?

 

Thanks, CR!

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Didn't realize that the water supply was hot water. Interesting!

 

Is it normal for the solenoid head to be warm to the touch when it's opened? I mean, easy to hold onto so not scorching hot, but warmer than the waterline feeding it?

 

Most houses I've seen have the humidifier water coming off the cold rather than the hot, but I doubt it really makes much of a difference. Also normal (as noted) for the solenoid to be warm to the touch, and this is doubly true if you're passing hot water through it rather than cold.

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