Question about Aprilaire 550 Humidifier

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Aprilaire 550 humidifier

My Aprilaire 550 has not been working. I checked the voltage on the swich and the wires to  the solenoid. They all have current going through. The water is coming out of the lines, so is my solenoid shot? Darwin

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  • doreenb Jan 27, 2009

    I had a new furnace installed and since then my humidifier will not work. It is getting power and the filter is new but thats about it. Its getting water also.



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Did you clean the orfice ? It is located on bottom of solenoid. It is plastic with a very small hole.The hole gets plugged and you can clean it or buy a nw one for 50 cents.

Posted on Nov 12, 2008


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1 Answer

No water to furnace humidifier

It's probably the saddle valve. The self-piercing needle rusts and clogs the water line. Replace the saddle valve with a non self piercing one. Also, check the voltage to the solenoid valve on the humidifier. You should be getting 24 ac volts. If not, replace the transformer. If voltage is present and still no water, then replace the solenoid valve (very expensive).

Aug 18, 2012 | Aprilaire 550 Humidifier

1 Answer

Aprilaire 550 not turning on

Hello, apply power directly from transformer to solenoid valve, it it does not turn on the solenoid valve must be replaced. If there is no voltage to the solenoid then follow the wires back and see where there is no voltage.

Nov 18, 2011 | Aprilaire 550 Humidifier

1 Answer

How do you test a solenoid valve ?

Hello, I like to apply voltage directly to the solenoid valve to see if is working. Just take the two wires from transformer and connect to solenoid valve, if the valve clicks and water starts flowing the valve is good

Oct 29, 2011 | Aprilaire 550 Humidifier

1 Answer

My aprilaire 550 water solenoid is constantly clinking on and off while the furnance is running. What could be the problem

Hello, check for any loose wiring between the solenoid and transformer this usually causes the solenoid to click on and off.

Feb 18, 2011 | Aprilaire 550 Humidifier

1 Answer

No water coming out of egress outlet of solenoid when humidifier is on and water is on.

Hello, verify if the valve is getting 24 volts, if it is and the solenoid is not opening then replace it. If it is not getting 24 volts then start at the transformer and work you way toward the solenoid to see where there is no voltage.

Feb 12, 2011 | Aprilaire 550 Humidifier

1 Answer

Aprilaire 550 There is no water going through the solenoid to the feed tube. I recently purched a new solenoid.

The first thing to check is if you are getting 24 volts at the transformer, if you are not then turn off power the transformer and check continuity. u should have continuity if not replace the transformer. If you are getting 24 volts at the transformer then apply 24 volts directly from transfomer to solenoid valve you should hear the solenoid cleck open and let the water in, if not then the solenoid is bad and must be replaced. If the solenoid does work by applying voltage directly to it then check the
wiring and make sure it;s all tight. Also check the humidistat and current sensing relay/sail switch to make sure it's functioning properly.

Jan 13, 2011 | Aprilaire 550 Humidifier

1 Answer

How do I check whether my Lennox humidifier (made by Aprilaire) is getting current going to the valve solenoid? I've checked across the wires going into the valve and found no current. Thanks for your...

If you are not getting voltage to the solenoid valve then start at the transformer and check if you are getting 24 volts. If not then turn off power to the transformer and set your meter to continuity and check the transformer, if you dont have continuity the transformer is bad and must be replaced. If the transformer is good then check the wring to make sure the connections are tight and the humidistat, if that check out good then the current sensing relay/ sail switch is bad.

Jan 12, 2011 | Aprilaire 550 Humidifier

1 Answer

Aprilaire 550 makes extremely loud grinding noise when turned on

yes it should be bypass but solenoid could be trying to open but the voltage to it may be to low if you have 24v ac power at the 2 small wires. but to change shut down power to furnace and water to loosen the 2 compression nuts unwire they cant be reversed so dont worry then 2 mounting screws then reverse to install

Dec 17, 2009 | Aprilaire 550 Humidifier

1 Answer

Power is off to aprilaire 550

The Aprilair Hum. donot have a restart button. All there is there is just a 24VAC Solenoid that opens and lets the water flow throu a tube. Check your humidistat, check your wire going to the furnace control board and also your current sensing relay if you have one.

Feb 01, 2009 | Aprilaire 550 Humidifier

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