Aprilaire 400 owner manual Principle of Operation

I. PRINCIPLE OF OPERATION

With your purchase of a humidification system, you have invested in a humidifier that operates on the evaporative principle – nature’s own way of adding moisture – and will provide the proper relative humidity throughout the heating season. It is very possible that you have questions concerning your new humidifier – questions on what it can do for you, and what you should do to receive maximum benefits from it. This booklet is intended to help you do exactly that.

Nature, in producing an invigorating comfortable April day, combines just the right temperature and the right amount of moisture. Aprilaire Humidifiers employ the same principle, with refinements, to give you the proper relative humidity for maximum allowable comfort all winter long.

The important considerations in the evaluation of a humidifier are Positive Control, Sufficient Capacity, Trouble-free Performance and Minimum Maintenance. The operating principle of your Aprilaire provides all of these advantages. Here, briefly, is the method:

The Aprilaire Humidifier is installed to operate in conjunction with the furnace blower motor. When the Aprilaire Humidifier Control calls for humidity and the blower motor is operating, water flows to the distribution tray located at the top of the unit. The water is uniformly distributed across the width of the tray and through a scientifically designed system of outlets. It flows by gravity over the Water Panel® evaporator, the heart of the unit. Dry, hot air is moved through the moisture-laden Water Panel evaporator where the evaporation takes place. The now humidified air carrying moisture in vapor form (nature’s own way) is circulated throughout the home.

The correct water flow is determined by an orifice equipped with each drain type unit. When the unit is operating, there will be a small, steady stream of water to drain, which flushes away most of the trouble-causing minerals. Do not use the saddle valve to regulate the water flow. It is designed to be completely opened or closed. The minerals and solid residue not trapped by the replaceable Water Panel evaporator are flushed down the drain in the Models 550, 600 and 700. This is the most effective and least expensive method to dispose of trouble-causing minerals. The drain also eliminates the problems caused by stagnant water.

There are some homes where drain facilities are not accessible or available. For these situations, or where high water hardness is not a problem, the newest Aprilaire, Model 400, is designed to satisfy these applications.

- 2 -