Models 350 & 360; Models 400 & 400M - Aprilaire 350 Safety & Operating Instructions Manual

REQUIRED MAINTENANCE INSTRUCTIONS
(APRILAIRE HUMIDIFIER MODELS 350 & 360)
WARNING
120 volts may cause serious injury from electrical shock. Disconnect power and
shut off water supply before servicing.
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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.
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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
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REQUIRED MAINTENANCE INSTRUCTIONS
(APRILAIRE HUMIDIFIER MODELS 400 & 400M)
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 Evaporative
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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:
Manual Humidifier Control (Model 400M): With the HVAC blower operating, turn up Humidifier
Control and check system operation.
Automatic Digital Humidifier Control (Model 400): (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.
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90-1077
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