Why does it make a constant hissing sound?

Sounds like the solenoid valve on your humidifier is stuck in the open position. Shut off the water supply to it from the saddle valve on the cold water pipe as a temporary fix.

Hello, water not reaching the humidifier can be caused sediment buildup in the strainer of the solenoid valve, a faulty solenoid valve, sediment at the saddle valve, or no power to the solenoid valve. The fan will run continously if the relay that engages the fan is stuck as it is gettimg a constant 120 volts.

You need to turn water off. Release pressure on system by opening a faucet or something. Drill a hole in galvanized pipe slightly larger than piercing needle on saddle valve. Open up piercing valve so it extends out, that way you can see it go in previously drilled hole. Finish valve like you would on copper pipe. Keep piercing valve closed until 1/4" pipe is done being hooked up. Turn on the previously shut off water valve

The saddle valve that controls the water is only to be used as an "on" or "off" control. It is not recommended as a throttle valve since it can leak if it is not placed in the full open or fully closed setting

Normal 0 false false false MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} Your Aprilaire Humidifier is designed to operate in conjunction with your furnace blower motor. Most installers wire a humidifier to operate when the furnace is calling for heat. To determine if your Aprilaire Humidifier is maintaining proper humidity, turn up the heat temperature 5 degrees above the current room temperature on your thermostat and set your humidifier control to call for humidity. The humidifier control is located on the cold air return duct. To set your humidifier control to call for humidity, turn the control dial to the off position and slowly rotate the dial until you hear a “click” on the control. You should also hear a click at the solenoid valve located on your Aprilaire unit. The humidifier control will have a click point at the current relative humidity level in your home. If the current relative humidity is 45% or the outdoor temperature is above 60F, the control will only operate the humidifier in the test mode.
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1. No click at the solenoid valve indicates an electrical problem. Contact your heating and air conditioning dealer to further check the electrical components of your Aprilaire Humidifier.

1. The click sound at the solenoid valve indicates there is electricity to the solenoid valve. By turning the dial of your humidifier control to a setting above the “click point” you should see water coming out of the drain line within a few minutes which would indicate your humidifier is working.

1. If the solenoid valve makes a click sound and there is no water draining from the unit, this would indicate the flow of water is being obstructed.

1. To determine if water flow is being obstructed, turn the dial of your humidifier control to the off position. The first location you would want to check for an obstruction would be at the saddle valve located on the water line supplying water to the humidifier. When checking the saddle valve, you want to make sure it is completely open. This can be done by turning the valve all the way to the left. If anything is clogged, it can be dislodged by turning the saddle valve all the way to the right and back to the left. Once this is done, turn the humidifier control dial above the click point and you should see water coming out the drain line.


If water is still not coming out of the drain, check the orifice and in-line strainer to make sure they are not clogged. The orifice is located in the tube on the discharge side of the solenoid valve and the in-line strainer is located on the inlet side of the solenoid valve. You may clear the orifice by inserting a needle through the small opening. Clean the strainer by running it under warm water to dislodge deposits or replace. After clearing and re-installing the orifice and strainer (be sure to double wrench all water connections), turn the humidifier control dial above the click point and you should see water coming out the drain line.

turn off the water to your house and replace the saddle valve. you should be able to ge from any hardware store

Disconnect the two low voltage wirings going into the solenoid valve. If the water does not stop running after a few minutes the valve is bad. When you check your local area to price a new valve. Also get a price for a new humidifier. You will be surprised to find that a whole new unit isn't that much more. Or should I say that you will find that the replacement parts are overpriced.
Good Luck
HVAC Teacher

you should have a humidistat that should shut it off when set to zero. if the water solenoid is stuck, water will keep coming out even when the system is not heating. all humdifiers will have a water line ran to them. yours is most likely a 1/4"copper line that runs from the water solenoid on the side or bottom of the humidifier to a saddle valve on one of your water lines. this saddle valve is usually installed very close to the water heater. follow the line to the valve and shut the water off. sometimes you have to loosed the nut on the water valve to get it to turn easily. do not loosend the nut more the 1/4 turn and then make sure you tighten it back down after shutting the water off.

Hello All,

Was having a similar problem. Disconnected the source line and opened saddle valve. I was getting water to the solenoid but nothing out the other side. My humidistat doesn't have a "test" setting, it's either off or the highest humidity. I held the outbound line in my hand and experimented with adjusting both sadlle valve and humidistat. I didn't get any water until I opened the saddle valve MUCH further than I thought was necessary and turned the humidistat to near the highest setting. Once I had water coming though I experimented with the setting on the humidistat, turning it off and then slowly increasing the humidity until the solenoid clunked and water started coming out. I would recommend anyone having this same problem to open the saddle valve all the way (I was surprised how many turns that took) and set the humiditstat to it's highest setting.

Randall

Sounds as if you feel the problem is the saddle valve. Check to see if water is available at the humidifier. Close the saddle valve, disconnect the water line at the humidifier side, then slowly turn the saddle valve back on. If you never see water, then correct the saddle valve. You can get details here: http://www.naturalhandyman.com/iip/infxtra/infsad.html#1
If you are getting water, but dont think that the unit is operating try sending 24VAC directly to the hunidifier and see if it operates, bypass the humidistat etc.