Aprilaire 400 owner manual III. Operating Instructions, Effect of Water Characteristics

III. OPERATING INSTRUCTIONS – 550

Your new Aprilaire Humidifier is controlled by a manual humidistat installed either in the living area or in the cold air return. It is important to anticipate a drop in temperature and reduce the setting accordingly to avoid excessive condensation. For example, with an outside 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.

IV. ADDITIONAL INFORMATION FOR ALL MODELS

Be sure to keep fireplace dampers closed when not in use. They provide an excellent escape route for heat, as well as humidity.

On occasion, indoor moisture producing activities such as clothes drying, cooking, showers, etc., may raise the relative humidity level higher than it should be, even though the Aprilaire Humidifier is not operating. Telltale indications, again, are condensation or frost on cold surfaces such as windows, doors, walls, etc. If such condensation persists for several hours, your home should be ventilated to dissipate the potential damaging excess moisture levels.

V. EFFECT OF WATER CHARACTERISTICS

Your humidifier will operate effectively using either hot, cold, hard or mechanically softened water. Whether to use available tap water, even though it may be quite hard, or chemically softened water, is a common concern to homeowners when installing a humidifier.

Water used in homes contains varying amounts of minerals. The residue remaining as a result of hard water evaporation is primarily calcium and magnesium components and is usually quite hard, scaly, and dense.

Residue from softened water tends to be soft and fluffy and has a greater volume than hard water scale. The service life of a Water Panel evaporator may be extended by using hard water. In either case, the Water Panel evaporator is usually changed once a year with the exception of the Model 400 which should be changed twice a heating season. In the drain-equipped models, most of these solids are effectively controlled by flushing them down the drain.

- 8 -