Question about Aprilaire 550 Humidifier
Did you just install this unit, or has it been working for a while and just stopped?
1. If you just installed it, the solenoid wires (yellow) must be hooked up to switch in when you have a call for heat.
a) use a current sense relay OR
b) connect 120V & neutral to "HUM" terminal and neutral on heater control board.
2. If it has worked before, maybe the saddle valve is plugged. Turn the "T" handle all the way clockwise, then all the way out CCW. You can hear the water start flowing. Loosen compression fitting at solenoid valve to make sure water is getting there.
3) Also, you must supply 24V to the circuit to open the solenoid valve. Check your wiring. It depends on the model what way to wire it and I cannot go into that here.
4) Testing: Turn off humidistat control. Turn on heat, wait for blower to come on. Turn humidistat control to test posn. Solenoid valve should click. This will put water into top of Aprilaire tray, after few minutes it will dribble out bottom clear vynl tube to the
Posted on Jan 29, 2008
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