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AprilAire 400 Whole House Water Saver Furnace Humidifier

Aprilaire 400

Retail: $399.99 /ea
You Save: 18%
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Retail: $399.99
You Save: 18%
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Keep your home comfortable and your life simple with the AprilAire 400. This whole-home water saver furnace humidifier is manufactured and designed in the United States of America by AprilAire, a trusted, industry-leading name in indoor air quality solutions. With a unique evaporation process, this unit conserves water and eliminates any need for a floor drain. Covering up to 4,000 square feet and offering a 17-gallon-per-day capacity, this automatic humidifier features dual sensors, allowing for monitoring and response to indoor relative humidity and outdoor temperature for optimal humidity in your home 24 hours a day, 7 days a week. A convenient digital control gives you all the information and options you need, including water panel change and service reminders, humidity percentage, and more. Maintain optimal humidity, reduce allergy, asthma, and respiratory infection symptoms, minimize dust mites, fungi, viruses, and bacteria, and more with this incredible unit!

Note: Professional installation is required to ensure proper installation, operation, and regular maintenance.


  • Brand: AprilAire
  • Part Number: AprilAire 400
  • Pack Size: 1
  • Weight: 9.25 lbs.
  • Capacity: 17 gallons per day
  • Room Size: 4,000 sq. ft.
  • Voltage: 24V
  • Amperage: 0.5
  • Limited Warranty: 5 Years

Additional Features:

  • Healthy humidified air may reduce overall heating costs and help you feel warmer during the winter.
  • Set your desired humidity level on the humidity control. No intervention needed.


  • Installation instructions and template
  • Humidifier with built-in bypass damper
  • 24 VAC transforner
  • Automatic digital humidifier control
  • Outdoor temperature sensor
  • Saddle Valve
  • Solenoid valve
  • AprilAire 45 water panel


Frequently Asked Questions:

Is everything for installation included?

  • Yes, this comes with all equipment necessary except common tools. Please note that AprilAire states installation by a qualified HVAC technician is required, or the warranty will be voided.

Can this be installed in an unheated attic?

  • The AprilAire 400 should not be installed where freezing temperatures may occur. Other general guidelines for installation are included with this item.

Compatible Parts:

The AprilAire 400 Whole House Water Saver Furnace Humidifier is the correct replacement for the following part numbers:

Part Number
24 Volt
Aprilaire 4004 In-Liner Strainer
Aprilaire 4040 Humidifier Solenoid Valve
Aprilaire 4231 Yellow Orifice 12-Pack
Aprilaire 45 Replacement Water Panel 2-Pack
Aprilaire 4788 Maintenance Kit with Water Panel 45
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