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Install and Service the Typical Powered Humidifier

The installation process to install a powered humidifier is very similar to the installation procedure for a bypass humidifier. The main difference is that the bypass humidifier requires a supply duct be installed to flow air through the unit. A powered humidifier has it's own small fan to deliver humidified air into the air handler's air stream.

This type of humidifier is very common. Most humidifier manufacturers have their own version of the powered flow-through unit. Between manufacturers, the differences are minimal.

Installation Procedure

  • Determine the best mounting location on the air handler or furnace supply plenum. Measure twice to ensure room for installation ease and serviceability. Unit must be located at least 3" above top edge of furnace. If the furnace has an air conditioning evaporator coil, make sure the humidifier location is completely above the coil location.
  • Locate the template and tape to the plenum in the desired mounting location. Mark the hole to be cut in the plenum.
  • Cut the opening. Be careful not to enlarge the opening.
  • Remove the front cover of the new humidifier. Disassemble the unit down to the bare frame. The water pad should come out by pulling the top toward you, up and out. For now, disconnect the water supply tubing from the pad housing.
  • Position the frame in the opening. Attach the frame to the plenum with sheet metal screws through provided mounting holes. The sides may have clips which lock sides to the plenum.
  • Reinstall the humidifier pad assembly. Reinstall the water supply tubing.
  • Reinstall the humidifier cover.
  • Wire up the high voltage side of transformer (typical 110volt wiring).
  • Mount the duct-humidistat above or before the humidifier, so the humidistat senses the true humidity of the air from the conditioned space.
  • Wire up the low voltage wiring or control wiring. One leg of the low voltage wiring goes directly to the solenoid valve. The other leg goes through a proving switch (current sensing relay, sail switch, or pressure switch), then through the humidistat, then to the solenoid valve.

    Most powered humidifiers have an integral 24 volt transformer, which eliminates the need to provide a field supplied 24 volt power source.

    Refer to manufacturers wiring recommendations. Some furnaces or air handlers have humidifier taps, which eliminate the need for a field-supplied proving switch.

    Wiring variations will be necessary if your home's primary heating source is other than forced air, or if your thermostat has humidity control capabilities.

  • Install drain tubing to a floor drain or other functioning drain location(drain must have downward slope to the home drain location).
  • Hook up the 1/4" water line. Most humidifiers come with a self-piercing saddle-valve. These attach around a copper water line. As the valve is tightened in, the water line fills with water and supply is alive to the equipment.

    Check your instructions. Most powered humidifiers accept hot or cold water, softened or hard water.

Water panel replacement / Service

1... Turn down humidistat. Turn off power. Remove cover and set aside.

2... Panel top should pivot towards you. Lift up and out.

3... Remove water distribution tray. You should be able to leave water line connected.

4... Remove media from frame (slide up and out).

5... Clean out hard water deposits and debris.

6... Check drain tube for flow and free of obstruction.

7... Slide new media into frame. Re-install water distribution tray. Reassembly opposite of disassembly.

8... Check operation.

End of heating season:
Clean your humidifier. Shut off water, turn off power to the unit, and turn off the humidistat.

Winter start up:
Refer to original start up procedures. Replace the water pad (this should be done every 1 to 3 months, depending upon your water quality). Turn power back on, set humidistat to desired level, and cycle the unit to verify operation. Check for water leaks, and verify that the drain hose is not plugged.

It is a good practice to shut off the water supply and power to the unit until you have returned from vacation.

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