Premium Digital Humidifier Control- on #8 and reading 25 % RH inside temp 67 degrees and outside about 20 degrees (F), why could this be happening.

Consumer question:

Premium Digital Humidifier Control- on #8 and reading 25 % RH inside temp 67 degrees and outside about 20 degrees (F), why could this be happening.

Aprilaires’ response:

Thank you for contacting us regarding the Aprilaire product line. We are happy to assist you with questions relating to Premium Digital Humidifier Control. 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.  When your HVAC system starts operating the humidifier control will display the current relative humidity. 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. The click point on the humidifier control indicates the current humidity level in your home. All Aprilaire Humidifiers are designed to maintain an indoor relative humidity level of 35% anytime the outside temperature is 20°F or above.  If the outside temperature is 20°F or above and you have less than 35% relative humidity, there may be an electrical problem, humidity may be escaping from your home, your furnace may have short running time, or water flow is being obstructed.

A. 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.

B. 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.

C. 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.

2. 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 outlet side of the solenoid valve and the in-line strainer is located on the inlet side of the solenoid valve (see attached).  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.

D. Low Humidity can also be due to humidity escaping from the home or short run time by the furnace. Perform the following: 

1. Close all areas which could allow air and humidity to escape such as; fireplaces, windows, doors, mechanical ventilation (fresh air exchanger), etc. The amount of mechanical ventilation should also have been considered when the humidifier was initially selected by the installing HVAC contractor.

2. If the furnace has a short running time, it will also affect the amount of humidity in your home.  One option is to operate your furnace blower motor constantly by switching the fan switch on your thermostat to the “on” position.  When operating the furnace constantly, it is important the humidifier is supplied with service hot water to provide the heat necessary for evaporation.  If you have any questions on how to do this, contact your heating and air conditioning dealer.

3. Your Aprilaire humidifier needs to be perfectly level.  If your Aprilaire is not level, you will not get proper water flow which will affect performance and the relative humidity in your home.  Check the water flow rate at the drain line.  Proper water flow for the Model 400, 400A, 500, 500A, 600 and 600A is three gallons per hour and you should be able to fill a quart jar in approximately five minutes.  For the Models 700 and 700A the water flow rate is six gallons per hour and you should be able to fill a quart jar in 2 ½ minutes. If you do not have proper water flow, the water flow may be obstructed.

4. The water panel requires annual replacement.  If the panel has been in use for more than one humidifying season, replace it.  The water panel can become clogged from mineral deposits left behind from the evaporation process.  A clogged water panel will affect the amount of humidity in your home.

If after trying the above you still have less than 35% relative humidity with an outside temperature of 20°F or above, contact your installing heating and air conditioning dealer for further assistance with this control. We would be happy to further assist you with any questions or concerns relating to the operation of the control. If there are any further questions please contact us at your earliest convenience.

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