The Aprilaire Model 600 (AM 600) Whole-House Humidifier is a humidifier for any season. Designed for use in large to mid-sized homes, the Aprilaire 600 Humidifier is one of eight updated humidifier models from Aprilaire and is widely considered to be the best bypass humidifier on the market. It features a built-in bypass damper which, when used with a bypass humidifier, means a damper that closes off the bypass duct in the summer to stop air from being “blown” into the return. This feature provides convenient installation due to the fact that its presence requires less additional parts. In addition, it provides quick changeover from winter to summer settings. A bypass humidifier gets its air movement through the water panel by the difference in pressure between the supply (hot air) plenum and the return (cold air) duct. The supply plenum is under positive pressure and the return duct is under negative pressure creating the necessary balance. For roughly $170, this humidifier will have no adverse effect on any component in the furnace, air cleaner or filter.

This humidifier is similar to the Aprilaire 400A, however the AM 600 humidifier requires a drain. Like other Aprilaire model humidifiers, the AM 600 can be mounted on the return or supply duct with equal effectiveness. Some key features of the AM 600 include the automatic digital control humidistat, outdoor temperature sensor, first humidifier water panel, saddle valve, and 24V transformer. The automatic digital control humidistat is a key feature that displays relative humidity level, shows the Aprilaire humidifier is operating and gives service alerts and notifications when it’s time to replace the water panel. This humidistat connects to the furnace thermostat terminals allowing the humidistat to sense when the furnace is providing hot air. The humidistat can also be wired to sense when the blower is running with or without hot air and also includes a manual mode resistor. The AM 600 comes with the option to install the aforementioned outdoor temperature sensor to properly monitor and adjust relative humidity settings in the home.

Introduced in October 2007, the AM 600 replaces the 220, 224, 440, 560, 560-A and 568 and almond colored 600 units. The new AM 600 is identical to the earlier 600A, except the new 600 does not include a second water panel or DVD video. The 600 provides the same performance benefits as other Aprilaire humidifiers including delivering up to 50% more moisture than other competitive units. It also features an evaporation capacity of 0.70 gallons per hour, or 17 gallons per day, as well as the ability to humidify homes that are up to 4,000 square feet. The Aprilaire 600 humidifier is completely automatic, with the option of manual functionality, so you can have control when you need it and let the house humidifier do the rest if you are not home. Additional series parts for the AM 600 include a maintenance kit, which comes with a new water panel, and water distribution tray to evenly distribute water to all parts of the water panel.