Price: $219.99
(as of Sep 27,2022 13:31:03 UTC – Details)



Aprilaire introduced the first evaporative humidifier for forced air furnace systems back in 1954. Since that time, Aprilaire continues to lead the industry in whole home humidification systems. Our evaporative humidifiers work by piping water into the distribution tray located at the top of the humidifier. The water is uniformly distributed across the width of the tray and through a scientifically designed system of outlets. It flows by gravity over the Water Panel evaporator. Dry, hot air from the HVAC system is moved through the moisture-laden Water Panel evaporator. Natural evaporation takes place, the water is turned to vapor, and the humidified air is circulated throughout your home.

This unit is uniquely designed to evaporate 100% of the water going into the humidifier.  It incorporates a special two-stage float system to maintain the optimal amount of water and protect against overflow.  In the unlikely event the float system fails, it is recommended an overflow tube (1/2 inch inside diameter) be installed to the base of the humidifier and run to a condensate pump, a sink, or a floor drain.  Follow the required maintenance instructions.

INCLUDED IN THE BOX: Installation instructions and template, humidifier with built-in bypass damper, 24 VAC transformer, manual humidifier control with sensor, saddle valve, solenoid valve, and Model # 45 Water Panels
Is Discontinued By Manufacturer ‏ : ‎ No
Product Dimensions ‏ : ‎ 10.25 x 15.38 x 15.75 inches; 8.75 Pounds
Item model number ‏ : ‎ 400M
Date First Available ‏ : ‎ February 24, 2010
Manufacturer ‏ : ‎ Research Products Corporation
ASIN ‏ : ‎ B005J3J0EA
Country of Origin ‏ : ‎ USA

BUY WITH CONFIDENCE This humidifier was designed and manufactured in the U.S.A. by Aprilaire – the inventor of the whole home evaporative humidifier, and the leader in indoor air quality solutions
CONSERVES WATER using a unique process that evaporates 100% of the water flowing into the water panel
FULL COVERAGE up to 4,000 square feet in tightly built homes with a capacity of 17 gallons per day
MANUAL HUMIDIFIER with a single sensor built into the standard control monitors indoor relative humidity for use in manually setting the percent humidity in your home
HUMIDITY FOR HEALTH Aprilaire Humidifiers can help you maintain optimal humidity in your home of 35% – 45% which has been shown to reduce the incidence of respiratory infections and symptoms related to allergies and asthma by minimizing the formation of bacteria and viruses, fungi, and dust mites. In addition, you’ll feel more comfortable while also preserving items in your home susceptible to damage from changing humidity or dry conditions
Air flow capacity: 250.0 cubic_feet_per_minute