24v Drum Bypass Model with Manual Control

GeneralAire 81

SKU: 81 Category:


The GeneralAire Drum Humidifier is based on the evaporative pad method of adding moisture to the air.  A polyurethane pad forms the surface of a slowly rotating drum which is hydrated as it turns in an automatically controlled level of water and is installed on a vertical plenum surface of any forced air furnace.  It is recommended that the humidifier be mounted on the return air plenum.  This humidifier can be installed with the outlet to the right, or to the left by reversing the motor mounting plate and bypass collar.

Standard Features:

  • Unique design allows for right or left-hand installation
  • Removable front cover and water reservoir slides out
  • Split drum permits easy separation from removable polyurethane foam sleeve
  • Fits vertical plenum of any forced air heating system
  • Includes 6″ diameter bypass assembly, 1/4″ tubing and saddle valve
  • M3 Select-Control Manual Humidistat included
  • High capacity, 18 gallons per day


Need help? Ask An Expert
  • TypeBypass
  • Maximum Coverage Area4500 Square Feet
  • Water Capacity (GDP)18 Gallons/Day
  • Electrical Requirements24 Volts
  • Gallons per Day18 Gallons
  • Bypass Duct Diameter6 Inches
  • Plenum Opening Size8x7.5 Inches
  • Width12 Inches
  • Height11.5 Inches

Product Reviews