The Model 400 drainless whole-home humidifier can be installed in manual mode (400M) with no control or in automatic mode with control (400A). It allows for 100 percent of the water in the units to be utilized in the evaporation process with virtually no standing water. The humidifiers also incorporate a unique patented water delivery system that eliminates the need for a reservoir and only needs 8 ounces of water to operate. Model 400A offers continuous automatic control of the humidifier and provides the optimum level of rh by monitoring and responding to both outdoor temperatures and indoor rh. According to the manufacturer, the automatic set-it-and-forget-it control keeps the home’s humidity level exactly where it should be throughout the heating season.

Aprilaire, P.O. Box 1467, Madison, WI 53701-1467; 800-334-6011;

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