Manual Humidistat:
(Automatic Humidifier Control – see pg 3)
Your new Aprilaire Humidifier is controlled by a humidistat 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 humidistat are based on years of research (see table 3) and experience as to what is best 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, but unfortunately, it probably would result in damage to your home. Observance of the recommended RH levels on your humidistat, therefore, is an important safeguard. Condensation of water on inside windows in the form of fogging or frost is usually an indication of too high relative humidities. 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° | 45% |
+30° | 40% |
+20° | 35% |
+10° | 30% |
0° | 25% |
20% | |
15% | |
|
|
The humidistat is a precision instrument that can be used to determine the RH accurately in your home during the winter. Turn the dial to the lower setting, then reverse the dial direction slowly until a “click” is heard. At this point, read the RH on the dial. This will be very close to the actual RH in your home.
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