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

Aprilaire 400M humidifier – Utilizes 100% if its water for a more comfortable living environment

The Aprilaire 400M humidifier is one of the newest of eight updated humidifier models in an elite line of Aprilaire humidifiers. The newest Aprilaire 400M humidifier series features a unique water-conserving design that works together with a manual humidity control to render a comfortable living environment with optimum humidity control. The water-conserving design of the Aprilaire 400M humidifier (Manual-control) operates using minimal water consumption as it eliminates standing water; therefore no drain line is required for its performance!

As the 400M does not require a drain line, it’s best suited for the water conservation minded owners, and for homes with septic system applications - where a floor drain isn’t available. The evaporative capacity of the 400M is 0.70 gallons per hour. This flow rate allows the Aprilaire 400M humidifier to efficiently humidify tightly-constructed homes up to 4,000 square feet. The Aprilaire 400M humidifier purchase includes an Aprilaire #45 water panel, Manual Humidistat, saddle valve, and a 24V transformer.

With the Aprilaire 400M humidifier you can avoid the damaging effects of low humidity levels that can induce negative symptoms of allergies and respiratory ailments such as dry skin and sore throat. The Aprilaire 400M humidifier keeps these and similar problems at bay so you’re ensured a healthy living air environment for you and your family.

In order to receive the best performance from your Aprilaire 400 M humidifier, you will need to replace the water panel twice a year, beginning before the beginning of the heating season or after it ends. The saddle valve of the Aprilaire 400M should be replaced every 5 years; the strainer and orifice need replacing every 3-5 years.


If you need any more information or have any questions as you consider an Aprilaire 400M 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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