Aprilaire Humidifiers

Model numbers map to type: the 400 and 500 are bypass units, the 600 and 700 are fan-powered, and the 800 is a steam unit.

Choosing an Aprilaire

Aprilaire 500: a compact bypass model for small to mid-size homes. It uses water panel #10.
Aprilaire 400: a larger bypass model. It uses panel #45.
Aprilaire 600: a fan-powered unit, no bypass duct needed. It uses panel #35.
Aprilaire 700: a high-output fan-powered unit for larger homes. It uses panel #35.
Aprilaire 800: a steam model for high output or heat pump homes, which needs electrical work.
Automatic digital control: adjusts humidity with outdoor temperature to limit condensation.

Confirm the panel number on your unit's door before ordering pads from Whole House Humidifier Pads. Compare other brands in Furnace Humidifiers.

FAQs

Which Aprilaire humidifier do I need?

It depends on home size, furnace layout and heat source. The 500 suits smaller homes with room for a bypass duct, the 600 and 700 fan-powered models suit homes without bypass space or needing more output, and the 800 steam unit suits heat pumps. Check Aprilaire's sizing chart for your square footage.

What water panel does my Aprilaire use?

Panel #10 fits the Aprilaire 110, 220, 500 and 550 series, panel #35 fits the 600 and 700 series, and panel #45 fits the 400 series. The panel number is usually printed inside the cover. Check it before ordering, because panels are not interchangeable between these groups.

How often should I replace the Aprilaire water panel?

Aprilaire recommends replacing the water panel once per heating season, or more often with hard water. A panel clogged with minerals evaporates less water and reduces output. Many owners change it each fall when they turn the humidifier on and check it midwinter.