Question about Aprilaire 700 Humidifier

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Water not flowing into Aprilaire humidifier

I went to change the filter and notice no water was flowing. The unit remained completely dry even after running in test mode.

I searched here and could not find the solution, but after troubleshooting I did solve the problem (posting this as a solution below)

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  • kjohndoe Nov 28, 2008




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    1. Turn
      off the water valve to the unit. If
      it is a “vampire tap” (screws into the pipe), turn it clockwise until it
      turns all the way into the pipe

    1. Unscrew
      the copper pipe left of the Solenoid (brass piece with wires under the
      humidifier). Watch out for some
      remaining water.

    1. Slowly
      turn the water valve back on. If no
      water comes out or it is slow dripping, the problem is with the valve
      or the pipe itself.

    1. If
      this is the case take the other side of the pipe off the value/ tap and
      blow throw it to clear obstructions. You may need to replace this if there is
      resistance due to mineral build up.
      My problem was the vampire tap going into the pipe. The fix was to turn the valve all the way in and out several
      times until minerals clear out or replace the valve. On a vampire tap value this is involved given
      you need to drain the pipes. (This was my problem)

    If water does flow, next you need to check the Solenoid.

    1. Take
      this completely apart by removing the nut holding the Solenoid from the
      inner valve. Unscrew the plastic
      tube from the right and the two screws holding it to the humidifier.

    1. Blow
      through the plastic tube to make sure it is clear. Air will not flow as strong through it as
      the diameter is smaller.

    1. Use a
      pipe cleaner to attempt to clean each side of the solenoid. You will find a plastic filter in it that
      you should also clean and replace. Air will not
      pass through the solenoid due to the fact it is a closed valve (requires power to activate a magnetic filed (I think)). One could get creative to open it or test
      it, but I did not need to go that far.

    If all paths are clear and water is flowing properly, it is
    probably the solenoid, the wiring or the switch.

  • fabricista Nov 28, 2008

    Water is not flowing on the aprilaire 700 humidifier. But if I reset dial, while furnace is running the water flows. It does not flow on the next furnace cycle, though. Is the celenoid bad or the switch panel, and can I fix it myself?

  • kjohndoe Dec 02, 2008

    sounds like the switch / humidity sensor. When you turn it you should hear a click when it gets to the humidity level that requires draw. If you don't hear that it could be the switch

  • Anonymous Dec 04, 2008

    Same problem, fan runs, hear a click on the dial, just no water.



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Posted on Jan 02, 2017

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SOURCE: Humidifier control .

if humidifier was wired into thermostat circuit for power instead of seperate transformer , this can happen. you need to see if you voltage going to the solenoid valve. if you do , and it isn't opening, the valve is bad . this is assuming that it is using a # 50 relay to come on only when the fan runs . . make sure the water valve is open

Posted on Dec 28, 2007

  • 2 Answers

SOURCE: What should my humidifier be set at for the winter?

Hi, Jennifer:

I'm no expert, but those who are seem to agree that the first thing to check is your evaporator panel. Aprilaire recommends replacing it annually--so if you haven't replaced it recently, that would be the first step to take. Next, check the power supply to your Aprilaire unit. Turn the humidistat to 0%, and then turn it slowly back toward 35% until you hear a click at the unit. If you don't hear a click, you'll want to check that the unit is in fact getting electric power (you may want to get an electrician or furnace tech to do this). If you do hear the click, the next thing to check is whether you have sufficient water flow to your Aprilaire unit. On mine, I had to adjust my water supply saddle valve, as well as the inline valve on the discharge side of the solenoid (see prior post from this morning)--and this seemed to clear the lines and restore water flow. Once you achieve proper water flow, you will probably want to set your humidistat at 35% for winter temps of around 20 degrees F--but be sure to adjust it downward for colder weather. Comments, anyone?

Posted on Dec 15, 2008

  • 2 Answers

SOURCE: solenoid on Aprilaire 600

solenoid valves dont just burn up just like that you have a recurring restriction due to bad water.Check the saddle valve at the water heater first then check for postive water flow at inlet to the solenoid valve,if you have water flow the valve is clogged with sediment.

Posted on Jan 13, 2009

  • 1 Answer

SOURCE: water keeps running into humidifier even furnance blower is not

This sounds like, the 550 transformer is not connected to the blower motor power connection (in parallel)

Posted on Mar 04, 2009

  • 2 Answers

SOURCE: how do I know if my Aprilaire 550 humidifier is working?

Should the water flow through the water pannel al the time the blower is running?

Posted on Dec 18, 2009

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HI, Troubleshooting an Aprilaire Humidifier

Aprilaire, a manufacturer of indoor air quality products including thermostats, air cleaners and dehumidifiers, also offers a line of whole house humidifiers. Installed in your existing heating and cooling system, humidity is produced by a supplied water source that flows over a water panel before being distributed throughout your air through the heating and cooling system. Issues you may need to troubleshoot with your Aprilaire humidifier include error messages and the unit producing too little or too much humidity.

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You can get parts from the link below:

Hope it helps.

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Good luk
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