The Model 400M bypass humidifier is a high-capacity, water-conserving humidifier (0.70 gallons evaporated per hour) incorporating a water recirculation system for use where drain facilities are not accessible or available. It uses 100% of the water that goes into the unit. For those rare occurances where an automatic control is not practical, Aprilaireoffers a manual control to meet your needs. Humidifies up to 4,000 square feet if your home is tight in construction. The Model 400M is also a good choice for homes with heat pumps. Due to lower plenum temperatures the unit should be connected to your hot water supply line. This humidifier can be installed on the supply or return air ductwork. It is also left or right side reversible. Includes manual control humidistat, water pad, 110v to 24v transformer and manufacturer's special instructional DVD.

Other items needed for the installation that are not included: 1/4" copper tubing for water line, 6" round ducting and elbow for bypass air, 2-conductor 18 to 22 gauge wire. These items are available in our easy installation kit.