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Written by: Will Housh
Indoor Air Quality Expert and President of

Aprilaire 400 humidifier – Comfortable humidity with minimal water usage

The newest edition in the elite line of Aprilaire humidifiers is the Aprilaire 400 humidifier with automatic digital control. The 400 maximizes humidity control through a water-conserving design that also minimizes water use. This new evaporative technology enables the Aprilaire 400 humidifier to use 100% of the water delivered to the unit. This feature allows the Aprilaire 400 humidifier to operate without a drain line, making it suitable for homes with septic systems, for people preferring water conservation, and for applications where a floor drain is not available. The Aprilaire 400 humidifier comes with a built-in bypass damper onveniently labeled for both winter and summer settings. With a high evaporative capacity of 0.70 gallons per hour, the Aprilaire 400 humidifier is best suited for handling homes up to 4000 square feet - if they are tightly constructed .

Besides automatic digital humidity control and the water-conserving design, the Aprilaire 400 humidifier also features an Aprilaire #45 water panel, an outdoor temperature sensor, a self-piercing saddle valve, an automatic humidistat, a 24V transformer and installation instructions/plenum cut-out template from Aprilaire.

The truly automatic control and innovative design of the Aprilaire 400 humidifier allows for easy operation and maintenance. The Aprilaire 400 humidifier can also be used in manual mode without compromising the comfortable humidity levels, including the functionality of the unit. For best performance, the water panel of the Aprilaire 400 humidifier should be replaced annually (either before the heating season starts or at its end). The saddle valve of Aprilaire 400 humidifier needs to be replaced every 5 years while the strainer and orifice should be replaced every 3-5 years, or as needed.

If you need any more information or have any questions as you consider an Aprilaire 400 humidifier purchase, please do not hesitate to contact our customer support team via email by clicking here: I Have A Question.

As always, Thank You for shopping at We're happy to help and we appreciate your business!

Will Housh
Founder and President

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