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Aprilaire 700 Fan Powered Humidifier 18 GPD with Automatic Digital Humidistat

SKU 700

  • 4200

Are you suffering from dryness in your home? Tired of touching anything metal in fear of being shocked by static electricity? The Aprilaire 700 fan powered automatic humidifier is just what you need, covering up to 4,200 square feet!

  • Actual Square Footage: 4200
  • Actual Gallons Per Day: 18
  • Drain Required: Yes
  • Control: Automatic Digital
Technical Specs

  • Brand: Aprilaire
  • Genuine OEM Product: Yes
  • Type: Power Humidifier
  • Control Type: Automatic
  • Coverage: Up to 4,200 sq. ft.
  • Water Panel: Aprilaire #35
  • Evaporative Rate: .75 Gallons Per Hour
  • Electrical: 24V
  • Product Measurements: 15.9" W x 18" H x 10.34" D
  • Plenum Opening: 14.75" W x 14.31" H
  • Includes: 24V VAC Transformer, Automatic Digital Humidistat, Remote Temperature Sensor, Saddle Valve, 1 Aprilaire #35 Water Panel

This product comes with a 5 year warranty from the date of installation.

Same Day Shipping On Orders Placed Before 5:00 PM EST


Since 1954, when Aprilaire introduced the first whole-home humidifier,  it has been the industry leader in ducted whole house humidification.  The Aprilaire 700 fan powered automatic humidifier has led the charge in home comfort. 


With an 18 gallon per day output the Aprilaire 700 can humidify a home up to 4,200 square feet.  This unit mounts directly to the duct of your heating and cooling system, allowing the humidity to be placed into the airflow and distributed evenly throughout the home. The 700 humidifier hooks up to a water line so you do not need to worry about filling it multiple times a day. With a built in fan the humidifier pulls warm air directly from the furnace, increasing its effectiveness.


Benefits of Evaporative Humidification

  • Prevents Flu and Allergies
  • Neutrlizes Static Electricity
  • Reduces Pet Dander and Discomfort
  • Protects Fine Furniture and Wood Floors
  • Relieves Dry Skin & Scratchy Throats
  • Reduces Heating Costs


The 76 automatic controller that comes standard with the Aprilaire 700 humidifier mounts directly to the ductwork of your heating and cooling system to accurately read and deliver the appropriate amount of humidity.  Equipped with notification lights, you are alerted if your humidifier is not working properly (red), needs a new #35 water panel (yellow), or if it is working properly (green). Sensing the outdoor temperature and the indoor humidity levels, the automatic humidistat will call for the ideal amount of indoor relative humidity to ensure you and your family is as comfortable as possible.


The 700 humidifier by Aprilaire requires a plenum opening of 14 3/4" by 14 5/16".  For electrical reference, this unit operates on 120 Volts at 60Hz with a .8 AMP requirement.  Due to the nature of evaporative humidification this unit can be installed on either the supply or retun duct of the heating and cooling system. If the Aprialire humidifier is being installed on a heat pump system it is best to hook the unit up to a hot water line.


Using a genuine Aprilaire #35 water panel is highly suggested.  This water panel was designed specifically for the Aprilaire 700 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 #35 water panel.


Aprilaire recommends a #4750 maintenance kit be used each humidification season to ensure that your 700 humidifier is operating optimally.

If you have any questions regarding this product please feel free to email Sales@Humidifiers.com or call 1-800-707-8159 and one of our friendly Customer Experience Representatives will be more than happy to help.


  • Manual Mode Resistor
  • Quiet Operation
  • Easy to Read Automatic Digital Control
  • Ability To Install On Supply or Return Duct
  • Delivers up to 50% more moisture in comparison to other competitive units
  • Outdoor Temperature Sensor Informing Your System of the Most Accurate Humidity Level
  • Automatic Alerts Reminding You to Change the Water Panel Making Maintenance Easy and Worry Free

Customer Reviews

Aprilaire 700

February 14, 2014


I am totally satisfied with this product. Works better than other brands it replaced. Get the digital system. Highly recommend it and buying it from Humidifiers.com. They were prompt in handling my order and getting it to me.

Great product! Fast Shipping! Easy Install!

January 6, 2013


I purchased the Aprilaire 700 from Humidifier.com over the holidays. There was a little delay in processing my order, but it was very understandable since it was the holidays. One processed I got got my order quickly. The price was great and the shipping was quick!

I installed the Aprilaire 700 myself to my Rudd 80% furnace. I hooked the Aprilaire to a hot water line and mounted it on the supply duct. I didn't use the supplied digital control, instead I hooked the humidifier up to my 2nd generation Nest thermostat. I have no experience with HVAC but was able to do everything myself in about 6 hours of work including trips to the store etc.

Be aware that if you don't have a humidifier installed you will be to buy some items as stated in the instructions. It cost me about $125 in parts to install, but I had to buy some extra things like a relay and new thermostat wire because of my Nest Setup.

After 12 hours of use my house went from 12% humidity to 35% humidity. It's working well with or without the furnace being on. I can already notice a change and it's a very nice luxury to have.

I highly recommend this item so far and humidifiers.com. I also recommend installing yourself if you are handy.

Aprilaire 700

December 12, 2012


I have my unit set to the #4 setting and within 2 days my house went from 18% to 35% rh. I have an older house with a lot of natural oak so I was relieved when the humidity came up so quickly. If you are planning to install it yourself you will need some extra supplies like tin shears, 1/2" drain hose, and thermostat wiring. There is quite a lot to wire up since this unit works in unison with your furnace blower. However, once the unit is installed it is completely automatic. One feature that I really liked was that because it has its own fan, the warm air from your furnace is simply circulated through the unit and back into the duct. This eliminates the intake port that most similar units have. The only negative thing I can say is that the unit is not completely powered by the 120v plugin. You must install a 24v transformer (included with the humidifier) and wire up a separate circuit to operate the solenoid valve that turns the water on to the unit.

Good Product @ Great Price

November 17, 2012


After dealing with 3 small in-room humidifiers I decided to take the plunge to a whole house. It wasn't an easy install because of my down-flow furnace duct work arrangement, but once I figured that out it was easy. It arrived quickly and took me 6 hours to install, plumb, and wire. Works great so far. Love the automatic features. Set it and forget it!

Fast shipping.

September 18, 2012


Well, after about two years of stalling on buying a whole home humidifier, I finally decided on the Aprilaire 700. After checking some online retailers, I was extremely glad to find the absolute best deal on the humidifier here and the best pricing on shipping. Also I ordered this on a weekend, and got the product the next Wednesday. Thank you Humidifiers.com for excellent pricing and service! B

Fast Shipping

September 14, 2012


We are very satisfied with our dealings with Humidifiers.com. Delivery was made in a good time span. Thank you.

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