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MODELS 350 & 360
1. Front Cover
2. Feed Tube
3. Integral Bypass Damper
4. Water Panel Evaporative
Assembly
5. Distribution Tray
6. “V” Notches
7. Water Panel Evaporator
8. Scale Control Insert/Float
Chamber
9. Overflow Drain Line
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 evaporative assembly (4). Tip the Water Panel evaporative assembly forward and lift it
out of the humidifier. Do not tip the Water Panel evaporative 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). 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.
6. Slide the used Water Panel evaporator (7) out of the scale control insert/float chamber and
dispose of the Water Panel.
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. Inspect the plastic feed tube (2) by gently flexing it and looking for cracks or signs of wear.
Replace tube if it is cracked, brittle, or has been damaged.
9. Slide a new Aprilaire No. 45 Water Panel evaporator (7) into the scale control insert/float
chamber (8). Snap the distribution tray (5) back on the scale control insert (8).
10. Reinstall the Water Panel evaporative assembly (4) into the humidifier. Take care not to over-
bend the water level sensor assembly. Push the top of the Water Panel evaporative 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. Under normal operation the overflow drain line (9) will never have water in it. However,
inspect it for mineral deposits and replace if necessary. Make sure the drain line has a
constant downward slope and is not flattened or blocked.
13. Turn on the water supply. Return integral bypass damper to appropriate position.
14. Check system operation:
Automatic Digital Humidifier Control: (Automatic or Manual mode) Check system operation
and reset Change Water Panel indicator by setting the knob to “Test/Reset”. With HVAC
blower operating and HVAC calling for heat, humidifier will operate for one minute. DO NOT
LEAVE IN TEST MODE AS HUMIDIFIER WILL NOT OPERATE.
15. Set Humidifier Control to its original position.
1. Inlet Grille
2. Distribution Tray
3. Scale Control Insert
4. Distribution Tray Cover
5. Water Panel Evaporator
6. Drain Spud
7. Power Cord
8. Metal Housing
9. Water Panel
Evaporative Assembly
1. Note Manual Humidifier Control setting and turn dial to the “OFF” position.
2. Disconnect electrical power and turn off water supply.
3. Remove inlet grille screws (1). Remove grille from metal housing (8).
4. Lift the Water Panel evaporative assembly (9) out of the humidifier housing (8).
5. To remove the distribution tray (2) from Water Panel evaporative assembly (9), push down
on tray and pull out scale control insert (3). To clean the “V” openings of the tray, gently pry
the distribution tray cover (4) from the tray. 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.
6. Slide the Water Panel evaporator (5) out from the scale control insert (3) and dispose of the
Water Panel. Clean the scale control insert of mineral deposits. Replace the Water Panel
evaporator (Stock No. 35) with a Genuine Aprilaire Water Panel. Slide the Water Panel back
into the scale control insert (3) and snap the distribution tray cover (4) into the distribution
tray (2). Then snap the distribution tray back into the scale control insert.
7. Inspect the plastic 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.
8. Remove the drain line from the bottom of the humidifier and flex it to loosen any mineral
deposits or blockage. Then flush it with water under pressure. If it does not properly clear,
replace it. Slip the drain line back onto the drain fitting (6). Make sure the drain line has a
constant downward slope and is not flattened or blocked.
9. Reinstall Water Panel evaporative assembly (9) and intake grille (1).
10. Reconnect electrical power (7) and turn on water supply.
11. Turn up Manual Humidifier Control and check system operation.
12. Set Manual Humidifier Control to its original position.
REQUIRED MAINTENANCE INSTRUCTIONS
(APRILAIRE HUMIDIFIER MODEL 400A)
REQUIRED MAINTENANCE INSTRUCTIONS
(APRILAIRE HUMIDIFIER MODELS 350 & 360)
MODEL 400A
CAUTION
Sudden operation may cause personal injury or property damage.
Turn Humidifier Control to “OFF” or lowest setting before servicing.
90-1077
WARNING
120 volts may cause serious injury from electrical shock. Disconnect
power and shut off water supply before servicing.
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