Aprilaire 500 Humidifier from Bypass - 12 GPD with Automatic Digital Humidistat

The Aprilaire 500 ByPass FlowThru Whole Home Humidifier with Automatic Digital Humidistat that humidifies up to 3,000 sq feet and delivers 12 gallons per day.

The Aprilaire 500 Flow-Thru Bypass Whole House Humidifier with an automatic control is perfect for adding comfort to your home during the dry winter months. The Aprilaire 500 model is designed for use in small to midsized homes, efficiently humidifying up to 3,000 square feet and dispersing up to 12 gallons of water per day.  


The bypass unit mounts directly to the duct of your heating and cooling system, allowing the humidity to be placed directly into the airflow and distributed evenly throughout the home. Mounted on the supply or return duct (plenum), it is easily reversible for right or left hand installation. Additionally, this model connects to a water line so you don't need to worry about filling it multiple times a day.  


Benefits of Evaporative Humidification:

  • Prevents Flu and Allergies
  • Neutralizes Static Electricity
  • Reduces Pet Dander and Discomfort
  • Protects Fine Furniture, Wood Floors, and Musical Instruments
  • Relieves Dry Skin and Scratchy Throats
  • Reduces Heating Costs 


The Aprilaire 500 bypass humidifier comes with an Aprilaire60 automatic humidistat with an outdoor sensor. The Aprilaire60 humidistat mounts directly to your heating and cooling system to accurately detect and deliver the appropriate amount of humidity to your home, while the outdoor sensor works to transmit the outdoor air temperature and humidity to the humidistat. The amount of humidity your humidistat predicts is based on a formula that factors in both the current temperature of the house and the temperature / humidity outside the home, accurately controlling the humidity of your home without any work or guessing for the homeowner. Sensing the outdoor temperature and the indoor humidity level, the automatic humidistat will produce the ideal amount of indoor humidification to ensure you and your family are as comfortable as possible.

The Aprilaire60 automatic humidistat is equipped with notification lights to quickly alert the homeowner if the system is in need of maintenance.

Red = The humidifier is not working and needs your attention.

Yellow = The humidifier's #10 Aprilaire Water Panel needs to be replaced.

Green = The humidifier is working properly.  


The Aprilaire 500 Humidifier is Shipped to you as a Complete System that Includes:


This humidifier requires a plenum opening of 9-1/2" W by 9-1/2" H.  For electrical reference, this unit operates on 24 Volts at 60Hz with a .5 AMP requirement.

*Important note: If this humidifier is installed on a heat pump system it is best to connect the unit to a hot water line. 


Aprilaire recommends a #4792 maintenance kit be used each humidification season to ensure that your 500 humidifier is operating optimally. Furthermore, using a genuine Aprilaire #10 water panel is highly suggested. This water panel was designed specifically for the Aprilaire 500 humidifier and provides the most comfortable and efficient output. Don't trust the aftermarket products to provide the same quality and overall experience as the genuine #10 Aprilaire water panel. 


How to Videos


Changing The Water Panel
Annual Maintenance
Aprilaire 500 Bypass Humidifier Overview
Aprilaire 500 Bypass Humidifier Water Panel Change
Aprilaire 500 Bypass Humidifier Maintenance


If you have any questions regarding this product, please use the HVAC.com Contractor Directory to connect with a trusted contractor in your area.

  • Brand: Aprilaire
  • Genuine OEM Part: Yes
  • Type: Bypass Humidifier
  • Control Type: Automatic Digital
  • Coverage: Up to 3,000 sq. ft.
  • Water Panel: Aprilaire #10
  • Evaporative Rate: .5 Gallons Per Hour
  • Bypass Diameter: 6"
  • Electrical: 24V
  • Product Measurements: 15.62" W x 13" H x 10.25" D
  • Plenum Opening: 9.5" W x 9.5" H
  • Drain Connection: .5" (I.D.)
  • Contains: 24 VAC Transformer, Automatic Digital Humidistat, Remote Temperature Sensor, Saddle Valve, 1 Aprilare #10 Water Panel
  • This product comes with a 5 year limited manufacturer's warranty from the date of installation.
    Reviews Write a Review
    • Old Man

      I looked at a number of furnace humidifiers and this one is peerless! As a skilled DIY techie, I installed it with the excellent instructions and it performed perfectly from the minute I turned it on. The automatic controller is smarter than I and even adjusts to the outside temperature. I not only would recommend this, but the folks at HVAC are great!

    • greasy2004

      I bought the 500 series and have had zero issues. Easy to install, great instructions!

    • BreeBuddy

      Works great,much better than a messy portable.installed in about 2 hours.

    • bblair

      I installed an April-Aire humidifier on my furnace 30 years ago and would consider no other brand for a new replacement. I was upset to find the warranty would be void unless the new one was installed by a licensed technician (I am a retired engineer without an HVAC license). This would have more than doubled my cost, so I did the installation anyway. The unit performs fine. The Manufacturer should work with D.I.Y. people offering a little help (if needed), not void their warranty.

    • Barry

      I had visions of the controller going on the wall with the thermostat, but it landed up mounted on the ductwork in the crawlspace! The instructions mean it when they indicate it has to go ON the duct work. However, the manual controller version does mount on the wall. I think it will be a 'set & forget' deal, and I'm still young enough to get in the crawlspace, so it should be fine. I think the humidity sensor is a small integrated circuit that could have been separated from the controller, allowing it to be mounted on the wall. An idea for model 501. :)

    • Frank

      I ordered my Aprilaire Model 500 on a Monday morning and was installing it Tuesday night. That's right...it was on my porch in Michigan the day after I ordered it! I was very pleased to open the box and find the model 60 humidistat was now included with the 500. It meant a bit more of a pain when it came to wiring, but I'm not one to complain about a free upgrade. The ability to turn on the blower and run the humidifier without a call for heat is a nice option. I have it turned off, since I plumbed into cold water. But it only takes a flip of a switch to turn it on. The built-in damper is not the best when it comes to sealing the bypass duct. It might not be a bad idea to add another damper in the duct. This is my third Aprilaire humidifier I've purchased. I installed model 550s in both of my previous homes. The model 500 is an excellent replacement. Overall Aprilaire makes great humidifiers, and Humidifiers.com sells them at a great price and ships them very fast!

    • Andy

      This humidifier does a perfect job, i live in a cold very low humidity area, my family has dry skin, before we installed the humidifier, the air was always dry, everything had static, after installing it feels great, easy installation, my dad noticed a change in our house after putting it in so we put one in his house, Humidifiers.com is awesome to work with as well. -

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    Aprilaire 500 Humidifier from Bypass - 12 GPD with Automatic Digital Humidistat