Maintenance Instructions; Model 400 - Aprilaire 400 Owner's Manual

MAINTENANCE INSTRUCTIONS FOR
APRILAIRE HUMIDIFIER MODEL 400
CAUTION! Sudden operation may cause personal injury or
property damage. Turn Humidifier Control to "off" or
lowest setting before servicing.
1. Front Cover
2. Feed Tube
3. Integral Bypass Damper
4. Water Panel Evaporator
Assembly
5. Distribution Tray
6. "V" Notches
7. Water Panel
8. Scale Control Insert/Float
Chamber
9. Overflow Hose
10. Float Cover
11. Float
12. Water Level Sensor Assembly
1. Note Humidifier Control setting and turn dial to the "Off" position.
2. Turn off water supply. Turn the integral bypass damper (3) to the SUMMER position.
3. Press the tabs in the latches on the top and bottom of front cover (1) and pull cover off base
with both hands.
4. Carefully pull the plastic feed tube (2) out of the distribution tray (5) at the top of the Water
Panel evaporator assembly (4). Tip the Water Panel evaporator assembly forward and lift it
out of the humidifier. Do not tip the Water Panel evaporator assembly more than needed to
clear the housing to avoid over-bending the water level sensor assembly (12).
5. Unsnap the distribution tray (5) from the scale control insert (8). 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 any mineral deposits and clean the "V" notches (6). This textured surface helps ensure
even water flow for maximum performance. See page 3 if removed.
6. Slide the used water panel (7) out of the scale control insert/float chamber and dispose of
the water panel. Inspect the overflow hose (9) to make sure it is open.
7. Remove the float cover (10) and inspect the floats (11) and float chamber for mineral build-
up. Remove deposits as needed from floats, float chamber and scale control insert. Wash
the parts with a disinfecting cleaner. Reassemble the floats and float cover. Make sure
stems of both floats extend through openings in float cover and that floats move freely up
and down.
8. Check the condition of the feed tube and replace if tube is damaged or brittle.
9. Slide a new Aprilaire No. 45 water panel into the scale control insert/float chamber. Snap
the distribution tray back on the scale control insert.
10. Re-install the Water Panel evaporator assembly into the humidifier. Take care not to over-
bend the water level sensor assembly. Push the top of the Water Panel evaporator
assembly firmly back until it snaps into place.
11. Push the end of the feed tube back firmly into the distribution tray. Replace the front cover.
12. Turn on the water supply. Return integral bypass damper to appropriate position.
13. Check system operation:
Humidifier Control: (Automatic or Manual) Check system operation and reset change water
panel indicator by setting the knob to "Test/Reset". With furnace blower operating and
furnace calling for heat, humidifier will operate for one minute. DO NOT LEAVE IN TEST
MODE AS HUMIDIFIER WILL NOT OPERATE.
14. Reset Humidifier Control to its original position. Check operation.
MODEL
400
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