Aprilaire 448 User Manual

Page 14

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1. Note humidistat or control setting and turn dial to the “OFF” position.

2. Turn off water supply.

3. At the side of the unit opposite the airflow duct pull front cover (1) off hold-

ing with both hands and 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 plastic distribution tray (5) from the evaporative assembly

by unsnapping the white plastic holding strips from the tabs at the end of
the tray. 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 Scale Control Insert by twisting and flexing it to
loosen the calcium deposits, or use a putty knife. Inspect the Water Panel
evaporator (Stock No. 10 for Model 558 and Stock No. 35 for Model 568)
and replace with a new Genuine Aprilaire Water Panel if necessary. Slide
the Water Panel back into the Scale Control Insert with the black colored
spot up and snap the black distributor 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 pres-
sure and slip it back onto the black drain fitting.

9. Turn on water supply.

10. Check system operation:

Humidifier Control: Automatic Check system operation by setting the
knob to “Test.” With furnace blower operating and furnace calling for
heat, humidifier will operate for one minute.

11. Set Humidifier Control to its original position.

MAINTENANCE INSTRUCTIONS

for

APRILAIRE HUMIDIFIER MODELS 558-568

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 Evapo-

rative Assembly

5. Distribution Tray
6. ”V” Notches
7. Water Panel
8. Scale Control Insert
9. Drain Hose

5 6

MODELS 558-568