Manual Mode: (Automatic Mode – see pg 4)
Your Aprilaire Humidifier is controlled by a Humidifier Control installed either in the living area or in the cold air return. It is important to anticipate a drop in outdoor temperature and reduce the setting accordingly to avoid excessive condensation. For example, with an outdoor temperature of 20° the correct setting will be 35% relative humidity. If the temperature is expected to fall to 0° that evening, then merely reduce the setting to 25% several hours prior to the temperature change.
The recommended settings on the Humidifier Control are based on years of research (see Table 3) and experience for the average home. These settings represent a compromise between RH levels that would be most desirable for comfort reasons and humidity levels that are suitable for protection of your home. For example, a wintertime indoor RH of 50% may be considered ideal for comfort, but unfortunately, it probably would result in damage to your home. Observance of the recommended RH levels on your Humidifier Control, therefore, is an important safeguard. Condensation of water on inside windows in the form of fogging or frost is usually an indication of too much relative humidity. This same condensation can take place in other areas in your home with the possibility of damage resulting.
TABLE 3 – Outdoor-Indoor Relative Humidity
Outside Temperature | Recommended RH |
+40°F | 45% |
+30°F | 40% |
+20°F | 35% |
+10°F | 30% |
0°F | 25% |
– 10°F | 20% |
– 20°F | 15% |
If you would like to determine the RH in your home, follow these steps:
1.Activate the furnace blower by setting your thermostat to a higher temperature.
2.Turn the control dial setting to the “Off” position. Then, slowly turn the dial clockwise until you hear the solenoid valve”click on”. Next, slowly turn the dial counter clockwise until you hear the solenoid valve “click off”. This is the relative humidity in your home under existing conditions.
3.Return the thermostat and the Humidifier Control to their original settings.
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