| AprilAire 400M Whole-House Humidifier - Manual - Large Capacity Water Saver Furnace Humidifier for Homes up to 4 000 Sq. Ft. Model 400M bypass humidifiers use 100 percent of the water fed to the water panel –eliminating the need for access to a drain. The unit delivers up to 17 gallons of moisture to a home per day. A manual humidistat is provided with all 400M models; for... more | | $225.59 FREE shipping go to store |