Aprilaire Model 550 doesn't work

Old 01-29-13, 07:12 AM
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Aprilaire Model 550 doesn't work

Hi - my first post here and need some help...seems like everyone is uber helpful here!

Here's the situation - just moved into a resale home, and I think the humidifier Aprilaire model 550 is 10 years old...it isn't working and the house is dry. My hardwood floors now have gaps between them - roughly around 30% humidity according to my $2 hygrometer.

Here's what I know:
- Water valve is open, line to solenoid is cold
- Solenoid seems like it is closed (pretty sure it is)
- Humidstat clicks when I turn it
- Humidstat is connected to furnace panel
- Tried to reset the humidstat but actually there is no reset function. This is what it looks like

- I don't think anything is plugged either...doesn't even drip

I tested it while the blower and heat is on, so that it is activated. Don't know if the solenoid is broken...are these my next steps?

1. Bypass humidstat wiring and plug directly to solenoid to see if it opens. If it does open, replace humidstat?
2. Is it possible to manually open the solenoid? to see if water runs thru the line?

Thanks in advance!
Old 01-29-13, 07:13 PM
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Location: Rochester, Minnesota
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Where are the wire hooking up to in the furnace.

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