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MAINTENANCE INSTRUCTIONS for
APRILAIRE HUMIDIFIER MODEL 440
CAUTION! Sudden operation
may cause personal injury or
property damage. Turn
humidistat to “off” or lowest
setting before servicing.
1. Note humidistat setting and turn
dial to the “Off” position.
2. Remove two aluminum knobs (1),
swing up and remove top cover (2)
from humidifier.
3. Place finger under plastic water
nozzle (3) at top of water
distribution tray (4). Lift up to pop
outlet loose from hole and notch in distribution tray.
4. Tip forward and lift the complete plastic framed
evaporative assembly out of the humidifier.
5. To remove plastic water distribution tray from evaporative
assembly, push down on pan and out on plastic frame
(Scale Control Insert). Follow 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 any mineral deposits and clean the “V” notches
.
This textured surface
helps ensure even water flow for maximum performance. See page 3 if removed.
6. Remove Water Panel evaporator from Scale Control Insert and clean Insert by
flexing or using putty knife. Inspect Water Panel evaporator (Stock No. 12) and
replace if necessary with colored spot up. Snap plastic water distribution tray back
in place.
7. For units with plastic feed tubes, inspect the tube by gently flexing it and looking for
cracks or signs of wear. Replace tube if it is cracked, brittle or has been damaged.
8. Reinstall evaporative section in the humidifier with notch and hole in plastic water
distribution pan toward you. Pop nozzle fitting on end of feed tube into plastic water
distribution pan.
9. To reinstall top cover, hook back under lip of metal frame (5), drop in place and
tighten two aluminum knobs.
10. Remove drain hose and flush with water under pressure. Mineral deposits in hose
may be loosened by flexing hose.
11. Reattach drain hose. Make sure the drain hose has a constant downward slope
and is not flattened or blocked.
12. Turn humidistat to highest setting and make sure the furnace blower
is operating. Humidifier will operate if RH is less than 50%.
13. Set humidistat to its original position.
MODELS
440, 445 & 448
1. Cover Knob
2. Top Cover
3. Feed Nozzle
4. Distribution Tray
5. Metal Frame
3
4
5
1
2
1
MODEL 440
