Aprilaire 760 not working

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  #1  
Old 12-18-05, 10:02 AM
fbara
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Aprilaire 760 not working

Hi, I'm a new member here. I've searched through the posts and kind find an answer to the problems I'm having. I apologize in advance if this was already covered somewhere and I missed it.

I have an Aprilaire 760. It was installed new when I had the house built in '99. The first 3 years it worked fine. At the beginning of every winter I would change the water panel and verify it still worked. Three years ago I changed the water panel but the humidifier would not work. I'm not smart in the area of home repair and did not (at the time) have a volt/ohm meter to test the wiring. So I let it go.

This year it's seems to be more dry in the house than usual, so I want to get the humidifier working. I did a visual on all the wires by taking off the wire nuts. They look ok. The water line is connected to the hot water coming off my water heater, and the line feels warm where it connects to the humidifier selenoid (?).

I then checked the humidistat (standard Aprilaire one that came with the humidifier). When I turn the knob, I hear a 'click'. There are two wires attached to the humidistat: red and white. I put the volt meter on the wires and turn the knob until I hear a click. I don't see any voltage on the wires.

I don't know if I'm testing this correctly. I also don't know if I'm on the correct path for troubleshooting. I'd rather replace the humidistat than by a new humidifier. I would appreciate any help you could give me. Like I said, I'm new at this type of thing. Thanks!

Frank
 
  #2  
Old 12-18-05, 05:58 PM
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Frank,
You, too, can be a humidifier expert! I have been playing around with my old General humidifier (until recently replacing it -- that's another story) and came to realize they are pretty straightforward if you think it through.

Most humidifiers (and I think yours applies) are called "flow-through" models. By this is meant that water flows into a media pad. Air is blown through the pad, picking up moisture, but most of the water actually runs out the drain at the bottom of the humidifier. This is a deliberate design, intended to keep the media pad relatively clean.

The water flow is turned on by applying current to the solenoid valve. No current to the valve and it is "closed" (i.e., shut off). Sounds like in your case that you may not have water flowing through the unit.

In prior years, did you notice trickling water coming out the drain hose from your humidifier? How about this year?

If no water is coming out, then you just have to trace back and see why. Could be the shutoff valve is turned off (I assume you checked this...), or the shutoff valve is closed off with hard water deposits, or the solenoid valve is not opening, either because it's broken or it's not getting power.

P.S. Keep the air control damper fully open (usually a small lever near the air intake duct for the humidifier).


Steve in Omaha
 
  #3  
Old 12-19-05, 01:28 PM
fbara
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Thanks Steve, that's good info for me to know!

I tried taking the humidistat out of the picture. I figured the humidistat is just a relay, so I disconnected it at the switch. Next to the humidifier on the furnace I took the two wires that go upstairs to the humidistat and just connected them, thinking this will let me know if I have a large or small problem.

I turned on the furnace and the humidifier began working! I could hear the fan running and see water coming out of the bottom of the humidifier.

I waited until the furnace cycled and turned off to see if the humidifier would turn off also. It did. So now I'm thinking my humidistat might be bad. I ran out to Home Depot and Menards, but neither one carried humidistats. So I ordered a new one from an Aprilaire authorized dealer online. It should be here in 2 weeks. I'll hook that up and see what happens.

So for now, my humidifier works, but it's probably running at 100% all the time, instead of adjusting itself based on the inside humidity. That's ok for now, I'll watch out for condensation build up on the windows to determine if I should disconnect it for a day or two.

Frank
 
  #4  
Old 12-19-05, 01:45 PM
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Good! Sounds like a plan.

If you haven't been humidifying for a while (> a week or more), you probably won't have much trouble with overdoing it if you leave it on while waiting for the 'stat to come in -- at least for a while. As I've learned on this site, houses seem to take 1-2 weeks to re-humidify since furniture and construction materials will absorb the initial moisture in the air and you won't see much increase in the air. Good thought about keeping an eye out for condensation.
 
 

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