Aprilaire 550 humidifier not working

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Old 01-14-15, 05:11 PM
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Aprilaire 550 humidifier not working

Hi all, I am handy but have zero experience with furnace humidifiers. Bought a home with an existing Aprilaire 550 and is was not working. Went to look at it, saw a saddle valve with water line running into a solenoid valve. Humidity was 15% in home. Turned on saddle valve and within an hour, humidity in house was up to 30% with a stinky smell, great? Not so great. Went back to humidifier and there was a puddle on the floor and saw water coming out of humidifier box at bottom and actually coming out of the solenoid valve assembly itself. I turned off saddle valve and turned the manual humidistat control to off. After looking around the net and talking to an HVAC company about service, I decided to try to fix this myself. HVAC service told me a new water panel 10 for the aprilaire 550 would cost me $45 and I said forget it. This is what I think I know about this now: Solenoid is leaking and is bad. All maintenance parts inside humidifier are bad. I order a genuine Aprilaire 4040 solenoid and an aprilaire 550 maintenance kit. Now the wiring is where I am a bit confused? The solenoid is wired to a transformer inside my furnace and to the humidistat. There are 2 wire connected to each of the yellow solenoid wires with wire nuts. I assume I should just rewire as it is? So I plan to first replace the solenoid and reattach the electrical wires the same way and reattach the water lines the same way? Then, before turning power or water back on, replace inside parts with the new maintenance kit parts which include new hose and orifice, etc.

So my question really is, do you think I am on the right track to fixing my leaky aprilaire 550 system and get it working again? I can supply whatever other info you may need including any detailed photos. Thank you so much in advance for your help!

Marc
 
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Old 01-14-15, 06:13 PM
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Welcome to the forums.

If you have water on the floor it's because either the drain line is/was plugged or there is a buildup of minerals in the drain tray below the media filter. The #10 media filter should be replaced every year. Your getting the 550 kit which comes with a new tray. While you are servicing the unit make sure the drain line is clean. You can pour some warm water down it with a little bit of bleach.

There is no polarity to the yellow wires. Just put the same wires back on the same way.
Aprilaire has many good videos on their site.... http://video.aprilaireparts.com/

Any problems.... stop back. When you're finished stop back and let us know how you made out.
 
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Old 01-14-15, 06:26 PM
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Hi PJmAX and thank you for your welcome and response.

Let be explain the leaking in more detail. When the saddle valve is turned on, after a minute or so, water starts to leak out of the bottom of the Aprilaire unit towards the back of the unit, quite of bit of water. In addition, water actually comes out of the solenoid at the back of it where the nut is on the end. I figured the solenoid is bad and stuck open? Do you think this is the case?
 
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Old 01-14-15, 06:46 PM
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Did you try to tighten the brass nut slightly ? It's possible for the ferrule inside the nut to be leaking. Be sure to use two wrenches when tightening the supply line.

Either there is a crack in the drain pan or the drain is clogged. Is the tray filling and overflowing ?
 
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Old 01-14-15, 07:51 PM
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Thanks again.

The supply nut is tight and not leaking at that joint. I have visually seen the drain line running freely so that is not clogged. Water is overflowing from the tray. Also the flow of water does not stop whether the furnace is heating or not.

My personal feeling is that this unit has never been maintained and most parts of it are worn or broken. We just moved here and the bought the house from the bank since it had been foreclosed on. I think things were neglected here for a while.
 
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Old 01-14-15, 07:58 PM
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Humidifiers require maintenance..... probably best to replace the valve.

My Aprilaire valve isn't shutting off completely either.
 
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Old 01-14-15, 08:10 PM
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Thanks and will do! One more thing, is it normal for the solenoid valve to have two wires connecting to each of it's two wires? Each wire coming off the solenoid is connected to a wire going to the humidistat and to a wire going to the furnace 24V transformer. I don't know wiring, does this seem correct to you?
 
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Old 01-15-15, 09:46 AM
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No... that wiring doesn't seem normal. You need 24vac, a humidistat and a switch the closes when furnace blower is running. The wiring is in one loop.

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Old 01-15-15, 01:38 PM
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Thanks Pete, I appreciate your help greatly.

The wiring drawing you sent me is NOT how mine is wired. I guess I better think about re-wiring it so I can get it setup correctly before I put the new solenoid in.

If I understand your diagram correctly, I should connect one of the yellow wires on the new solenoid directly to the 24VAC transformer (which terminal) inside the furnace and then connect the other yellow wire from the new solenoid to one terminal of the manual control humidistat, then run a wire from the other terminal in the humidistat to the other side of the 24VAC transformer (which terminal) inside the furnace? Does it matter which terminal I connect wires to on the 24VAC transformer inside the furnace?

Another question I have is what do I actually NEED to install to get this Aprilaire working correctly? I have read that some need a separate 110VAC to 24VAC transformer, some need a #50 current sensing relay, and you definitely need the solenoid valve. My current install has wires connecting to what looks like a 24VAC transformer inside my furnace (maybe an accessory block?) My current install looks like wires are connected to this wiring block inside my furnace which are also connected to the solenoid and the humidistat. There is also another 24VAC transformer that is attached to an electrical switch box with wires coming out of it that have been just capped off with wire nuts. That's why this is a little confusing for me. Looks like things have been changed up on the original installation. I need to know what my exact wiring should be. Thanks

I just don't want to screw this up. Thanks again and Happy New Year to you as well.
 
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Old 01-15-15, 02:12 PM
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The long and short of it is you need to apply 24vac to the solenoid for it to deliver water. It doesn't matter in which order the items are wired and since it's AC there is no polarity.

If you don't have a current sensing switch then you must have or need some type of switched 24vac power that comes on either with the burner or the blower. Your transformer could possibly wired to the blower circuit to come on with the blower. A meter would be helpful in locating/confirming your 24v source.
 
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Old 01-15-15, 03:46 PM
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Pete, this is my current exact wiring for my Aprilaire 550, is it ok?

I drew up a PDF to show the exact wiring of my aprilaire unit. Please let me know if this current setup is correct or will work. Thank you very much!

Current Aprilaire 550 wiring.pdf
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Last edited by PJmax; 01-15-15 at 10:24 PM. Reason: added pic
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Old 01-15-15, 10:28 PM
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Nice diagram.

That will work but you need to make sure the furnace 24vac terminals you are connected to only have voltage when burner or blower is running. Connecting to the W and C terminals are not a good idea as the thermostat isn't designed to switch a humidifier along with the furnace.
 
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Old 01-18-15, 08:50 PM
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Pete, thank you for all your patient help. I rebuilt my Aprilaire 550 today and installed a new solenoid as well and it is working perfectly now. Thanks and have a great week. Marc
 
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