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Crucial safety precautions for electrical shock, sharp edges, and scalding hazards.
Precautions to prevent freezing, damage to furnace, moisture issues, and electrical/pressure problems.
Details humidifier dimensions, duct opening sizes, water feed rate, and electrical data.
Wiring diagram for the Model 500M manual control, including 120 VAC power source.
Wiring diagram for the Model 500A automatic control, using 24 VAC furnace accessory terminals.
Illustrates common installation configurations for upflow and horizontal systems.
Lists items included with the humidifier and items that must be supplied separately.
Details the process from removing the cover to securing the humidifier base and cutting openings.
Instructions for positioning the bypass duct and attaching it to the humidifier collar.
Guidance on wiring the humidifier control, emphasizing disconnecting furnace power first.
Instructions for connecting the water supply via saddle valve and the drain line to a floor drain.
Steps to check humidifier operation, ensure connections are watertight, and set the control properly.
Crucial safety precautions for electrical shock, sharp edges, and scalding hazards.
Precautions to prevent freezing, damage to furnace, moisture issues, and electrical/pressure problems.
Details humidifier dimensions, duct opening sizes, water feed rate, and electrical data.
Wiring diagram for the Model 500M manual control, including 120 VAC power source.
Wiring diagram for the Model 500A automatic control, using 24 VAC furnace accessory terminals.
Illustrates common installation configurations for upflow and horizontal systems.
Lists items included with the humidifier and items that must be supplied separately.
Details the process from removing the cover to securing the humidifier base and cutting openings.
Instructions for positioning the bypass duct and attaching it to the humidifier collar.
Guidance on wiring the humidifier control, emphasizing disconnecting furnace power first.
Instructions for connecting the water supply via saddle valve and the drain line to a floor drain.
Steps to check humidifier operation, ensure connections are watertight, and set the control properly.
The Aprilaire Model 500M and 500A are small bypass humidifiers designed to integrate with forced air heating and air conditioning systems to maintain optimal humidity levels in a home. These devices are intended for installation by qualified heating and air conditioning contractors to ensure proper function and safety. The primary function of the humidifier is to add moisture to the air, which can improve comfort and help protect wood furnishings and other household items from drying out in arid conditions.
The core mechanism involves a Water Panel® Evaporator, which is a porous pad that absorbs water. As air from the furnace's supply or return plenum passes through the humidifier, it flows over the wetted Water Panel®, picking up moisture through evaporation. A solenoid valve controls the water flow to the distribution tray, ensuring the Water Panel® remains saturated. Excess water drains away, preventing mineral buildup on the panel and maintaining efficiency. The humidifier includes a bypass damper that directs a portion of the system's airflow through the humidifier during the heating season (WINTER setting) and can be closed during the cooling season (SUMMER setting) to prevent humidification when not desired.
The Model 500M features a manual humidifier control, allowing the homeowner to set the desired humidity level directly. This control can be mounted on a return duct or on a wall in the living space, offering flexibility in placement. The Model 500A, on the other hand, incorporates an automatic digital humidifier control. This more advanced control continuously monitors the indoor humidity and, in some configurations, the outdoor temperature, to automatically adjust the humidifier's operation and maintain a consistent, comfortable humidity level without constant manual intervention. Both models require a 24 VAC power source, typically provided by a transformer included with the humidifier, and are designed to operate in conjunction with the furnace's heat call to ensure humidification only occurs when the heating system is active.
The Aprilaire humidifiers are designed for ease of use once installed. For the Model 500M, users simply adjust a knob on the manual control to increase or decrease the desired humidity level. The Model 500A's digital control offers a more sophisticated experience, often with a display that shows current humidity and settings, allowing for precise control and automatic operation. The bypass damper, which is integral to the humidifier, can be easily switched between "WINTER" and "SUMMER" settings by the homeowner, optimizing performance for different seasons.
The humidifiers are versatile in terms of water supply, capable of functioning with cold, hot, softened, or unsoftened water. Using hot water (up to 140°F) is recommended, especially with heat pump systems, as it enhances evaporative capacity, supplementing the reduced supply air temperature for more efficient humidification. The saddle valve provided for water supply connection is designed for full open or closed operation, not for flow regulation. The design allows for installation on either the supply or return plenum and is reversible for right-hand or left-hand bypass duct connections, providing flexibility to fit various HVAC system configurations.
Maintenance for the Aprilaire humidifiers is straightforward and designed to be user-friendly. The primary maintenance task involves replacing the Water Panel® Evaporator. The humidifier's cover can be easily removed by pressing top and bottom tabs, allowing access to the internal components. The feed tube can then be pulled out, and the Water Panel® Evaporator assembly can be removed and replaced. The scale control insert, located at the bottom of the evaporator assembly, helps manage mineral buildup and should be checked during Water Panel® replacement.
The design emphasizes accessibility for servicing. The drain spud and cap can be swapped for right-side or left-side bypass configurations, and the nameplate can be rotated if necessary for proper orientation. The continuous draining of excess water helps to flush away mineral deposits, reducing the frequency of deep cleaning required for the unit itself. The installation instructions emphasize ensuring all plumbing connections are watertight and all electrical connections are secure to prevent issues. The owner's manual, which includes instructions for operation and warranty information, is crucial for homeowners to understand proper usage and maintenance, thereby avoiding unnecessary service calls and ensuring the longevity of the humidifier. Regular checks of the humidifier's operation, especially at the beginning of the heating season, are recommended to confirm proper function and optimal humidity delivery.
General| Type | Bypass |
|---|---|
| Control Type | Manual |
| Voltage | 24V |
| Installation | Professional installation recommended |
| Warranty | 5-year limited warranty |
| Coverage Area | Up to 3, 000 sq. ft. |
| Mounting Location | HVAC Duct |
