Aprilaire 448 - Manual (Page 15)

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1. Note humidistat or control setting and turn dial to the “OFF” position.
2. Turn off water supply.
3. Press the tabs in the latches on the top and bottom of front cover (1) and pull cover off
base with both hands. Set aside.
4. Carefully pull the plastic feed tube (2) out of the nozzle (3) at the top of the Water Panel
evaporative assembly (4). Pull this assembly out by grasping at top and tipping out.
5. Remove the black distribution tray (5) from the evaporative assembly by lifting straight
up from the scale control insert (8). Lightly scrape out any calcium deposits and clean
the “V” notches (6) but do not scrape off the granular coating from the bottom.
This textured surface helps ensure even water flow for maximum performance. See
page 2 if removed.
6. Slide the Water Panel evaporator (7) out from the white plastic Scale Control Insert (8).
Clean the insert frame of calcium deposits with a putty knife. Inspect Water Panel evap-
orator (Stock No. 35 for Model 600) and substitute a new Genuine Aprilaire Water Panel
if necessary. Slide the Water Panel back into the scale control insert with the black col-
ored spot up and snap the black distribution tray back into place.
7. Re-install the Water Panel evaporative assembly into the unit by fitting its drain tube
into the round receptacle at the base of the unit. Push the assembly in at the top
against the beveled tabs that will hold it in place. Push the end of the feed tube back
firmly into the nozzle and replace the front cover.
8. Remove the drain hose (9) from the bottom of the unit and bend and flex it to loosen
the internal calcium deposits. Then flush it with water under pressure and slip it back
onto the drain fitting.
9. Turn on the water supply.
10. Check system operation:
Humidifier Control: (Automatic or Manual) Check system operation by set-
ting the knob to “Test.” 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.
11. Set Humidifier Control to its original position.
MAINTENANCE INSTRUCTIONS
for
APRILAIRE HUMIDIFIER MODEL 600
CAUTION! Sudden operation may cause personal injury or property damage.
Turn humidistat or control to “off” or lowest setting before servicing.
1. Front Cover
2. Feed Tube
3. Nozzle
4. Water Panel
Evaporative Assembly
5. Distribution Tray
6. “V” Notches
7. Water Panel
8. Scale Control Insert
9. Drain Hose
10. Integral Damper
MODEL 600