TABLE OF CONTENTS
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 Principle of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2 Operating Instructions – Models 400, 500, 600 & 700 . . . . . . . . . . . . . . . .4
• Digital Humidifier Control Indicator Lights . . . . . . . . . . . . . . . . . . . . . .4
• Blower Activation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
• Automatic Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
• Manual Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 Operating Instructions – Models 350, 360, 400M, 500M, 600M & 700M . . .9 Check the Humidifier Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9 Additional Information for All Models . . . . . . . . . . . . . . . . . . . . . . . . . . . .10 Effect of Water Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10 Annual Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11 Annual Summer Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12 Periodic Preventative Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
MAINTENANCE INSTRUCTIONS
Models 350 & 360 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Models 400 & 400M . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
Models 500 & 500M . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Models 600 & 600M . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Models 700 & 700M . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
Limited Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
WARNING
120 volts may cause injury from electrical shock.
Disconnect power and shut off water supply before servicing.
CAUTION
Sudden operation may cause personal injury or property damage. Turn the Aprilaire® Humidifier Control to “OFF” or lowest setting before servicing.
INTRODUCTION
Thank you for your recent Aprilaire® humidifier purchase. We appreciate your business and are pleased to add your name to our growing list of customers. You have invested in the highest quality equipment available. Aprilaire manufactures
Your humidifier will require periodic maintenance to assure continued fine performance. See page 11 to obtain service parts and/or replacement Water Panel® evaporators.
Please take a few minutes and read this booklet. This will familiarize you with the benefits you will receive from the equipment you just purchased and help you understand the routine maintenance that will be required.
Be sure to register your humidifier warranty online at:
www.aprilaire.com/warranty.
Genuine Aprilaire® Replacement Water 
Panel® evaporators are available from your 
installing contractor or from most other heating and air conditioning contractors in
your area. Use the dealer locator in our web site (www.aprilaire.com) or look in the Yellow Pages under Humidifying Apparatus or Heating & Air Conditioning Contractors. Purchase only genuine Aprilaire Water Panels to maintain peak performance.
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