Aprilaire 112 Operating and maintenance instructions

Maintenance Instructions:
Aprilaire Model 112
1. Note humidistat setting and turn dial to the “OFF” position.
2. Disconnect electrical power and turn off water supply.
3. Disconnect:
a. 120 volt electrical service.
b. Copper water supply line (1) and feed tube (2).
c. Drain line (7).
d. 24 volt leads (8).
4. Turn two swing locks (3), one at either side of lower housing of humidifier
flange.
5. Lift humidifier straight up until bottom of humidifier clears lip of lower
housing. Pull humidifier out at bottom, lower and remove.
6. Slide off three closure clips (4&5) that hold 2 halves of humidifier together.
7. Remove upper half of humidifier. Remove water distribution pan cover (6)
and remove any mineral deposits from the “V” notches. DO NOT SCRAPE
OFF GRANULAR COATING FROM THE BOTTOM. This textured surface
helps ensure even water flow for maximum performance. If the granular
coating has been removed, place several drops of liquid dishwashing soap on
the distribution tray. This will only need to be done once if there is no
granular coating.
8. Remove Water Panel evaporator and scale control insert (if used).
9. Remove Water Panel evaporator from scale control insert (if used). Clean
scale control insert of mineral deposits. If scale control insert is not used,
contact your dealer about obtaining one.
10. Install a new Water Panel evaporator, with colored spot UP, in scale control
insert (if used), or directly into the humidifier if insert is not used.
IMPORTANT: When installing scale control insert and Water Panel evaporator
into the humidifier, the insert spout must discharge directly into the drain.
11. Remove drain line (7) from the bottom of the humidifier. If applicable, flex it
to loosen any mineral deposits or blockages. Then flush it with water under
pressure. If it does not properly clear, replace it. Slip drain line back onto the

drain fitting. Make sure the drain line has a constant downward slope and is
not flattened or blocked.
12. Following Water Panel evaporator replacement and maintenance, reassemble
humidifier.
13. Reconnect electrical power.
14. Turn on water supply.
15. Check system operation: With the furnace blower operating and the furnace
calling for heat, turn up humidistat and check system operation.
16. Set humidistat to its original position.