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Maintenance Instructions for Aprilaire Models 440, 445 & 445A

Maintenance Instructions for Aprilaire Models 440, 445 & 445A

  1. Note Humidifier Control setting and turn dial to the "OFF" position.
  2. Disconnect electrical power and turn off water supply.
  3. Remove two aluminum knobs (1). Swing top cover up and remove from humidifier.
  4. Place finger under white feed nozzle (3) at top of water distribution tray (4). Lift up to pop feed nozzle loose from hole and notch in distribution tray.
  5. Pull out the water panel evaporator assembly by grasping at the top and tipping out.
  6. Unsnap the distribution tray (4) from the scale control insert. Follow the instructions below depending upon the type of distribution tray in your humidifier:

For trays with a synthetic fabric liner: Lightly scrape out or brush off any mineral deposits being careful not to stretch or loosen the synthetic fabric liner. Soaking the tray in vinegar or a lime-removing agent is helpful when trying to remove stubborn mineral deposits.

For trays with granular coating: Do not scrape off the granular coating, but lightly scrape out an mineral deposits and clean the "V" notches (5). This textured surface helps ensure even water flow for maximum performance. If the granular coating has been removed, place several drops of liquid dishwashing soap on the distribution tray. This will only need to be done once if there is no granular coating.

  1. Slide the Water Panel evaporator out from the scale control insert. Clean the scale control insert of mineral deposits. Slide the new Water Panel evaporator into the scale control insert with the colored spot up and snap the distribution tray (4) back into place.
  2. Inspect feed tube by gently flexing it and looking for cracks or signs of wear. Replace tube if it is cracked, brittle, or has been damaged.
  3. Reinstall the Water Panel evaporator assembly into the humidifier (with the whole in the distribution tray toward you) by fitting its drain directly over the round receptacle at the base of the humidifier. Push the assembly in at the top to a vertical position. Pop feed nozzle (3) on the end of the feed tube into hole and notch in distribution tray (4).
  4. Replace top cover (2) hooking back of cover under lip of metal frame (5) and tighten two knobs (1).
  5. Remove the drain line (if applicable) from the bottom of the humidifier. Flex it to loosen any mineral deposits or blockage. Then flush it with water under pressure. If it does not clear, replace it. Slip drain line back onto the drain fitting. Make sure the drain line has a constant downward slope and is not flattened or blocked.
  6. Reconnect electrical power and turn on the water supply.
  7. Check system operation:

Manual Humidistat: With the furnace blower operating and the furnace calling for heat, turn up humidistat and check system operation.

Humidifier Control: (Automatic or Manual mode) Check system operation and reset Change Water Panel indicator by turning the knob to "Test/Reset". With furnace blower operating and furnace calling for heat, humidifier will operate for one minute. DO NOT LEAVE IN TE S T MODE AS HUMIDIFIER WILL NOT OPERATE.

  1. Set humidifier Control to its original position.