PRINCIPLE OF OPERATION
With your purchase of this humidification system, you have invested in a humidifier that operates on the evaporative principle – nature’s own way of adding moisture
–providing optimum relative humidity (RH) 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 answer these questions.
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 optimum RH for maximum allowable comfort all winter long.
The important considerations in the evaluation of a humidifier are precise control, sufficient capacity, trouble-free performance and minimum maintenance. The operating principle of your Aprilaire humidifier provides all of these advantages. Here, briefly, is the method:
Except for Models 350 and 360, the Aprilaire humidifier is installed to operate in conjunction with the heating, ventilating, air conditioning equipment (HVAC) 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 humidifier. 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 humidifier. Dry, hot air is moved through the moisture-laden Water Panel evaporator where natural evaporation takes place. The now-humidified air carrying moisture in vapor form (nature’s own way) is circulated throughout the home.
Models 350 and 360 use service hot water (140°F maximum) for a heat source, as heat is needed for evaporation. While the water going to the humidifier is hot, the flushing water to the drain will be cold. The heat is extracted during the evaporation process.
The correct water flow is determined by an orifice provided with each drain type humidifier. When the humidifier 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 open or closed.
The minerals and solid residue not trapped by the replaceable Water Panel evaporator are flushed down the drain in the Models 350, 360, 500A, 500M, 600A, 600M, 700A and 700M. 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 Model 400A is designed to satisfy these applications.
Trouble-free performance and minimum maintenance are assured by the design features of the Aprilaire humidifier. All humidifier housing parts that come in contact with water are non-metal and will never rust or corrode. Neither heat nor water will affect them under normal operating conditions.
The Water Panel® evaporator, designed especially for uniform, high evaporation, and the Scale Control Insert (which encases the Water Panel) efficiently traps mineral deposits which are often the cause of damage to working parts in ordinary humidifiers. When properly maintained, no “white dust” will be distributed through the living quarters. The Water Panel evaporator is the heart of the humidifier and must be in good condition to assure high capacity trouble-free performance. It should be changed at least annually with the exception of the Model 400A which should be changed at least twice per heating season.
The distribution tray incorporates a synthetic fabric liner that is designed to deliver water uniformly over the entire top surface of the Water Panel evaporator, provided the humidifier is mounted level. It is normal for some mineral deposits to form in the distribution tray as it dries out between humidification cycles. These deposits can actually help distribute water in the tray, but if they block the openings, they should be removed as described in the “Periodic Preventative Maintenance” section of this manual.
Your Automatic Digital Humidifier Control works in conjunction with your HVAC to control the operation of the humidifier. The control senses indoor RH and outdoor temperature and automatically adjusts the operation time of the humidifier to provide the optimum humidity level in the home.
The digital readout on the automatic control displays the RH level inside the cold air return duct. RH is a measure of the amount of moisture in the air as a percentage of what the air can hold. Warm air can hold more moisture than cold air can. This reading will accurately indicate the RH in the living space when the HVAC blower is operating. Once the HVAC blower stops, the readout will not change.
The control has lights which indicate humidifier operation, when the water panel needs to be replaced and when service is required. See “Operating Instructions” for more information.
There are many humidifiers on the market. They all add moisture… with varying degrees of efficiency. None, however, offer the features, design, and performance incorporated into your new Aprilaire humidifier.
