Aprilaire 220 Service Manual page 18

3. ELECTRICAL COMPONENTS — All components should be tested in place making
sure all electrical connections are secure and there are no breaks in the service. If the
pump motor isn't working with the humidistat circuit closed (see diagram) and the fur-
nace blower running, disconnect electrical power and connect the blue motor lead
directly to the black power cord lead and check. If the pump runs, replace the
relay/transformer or 120 volt humidifier control (after Serial No. 337,941). If the pump
doesn't run, or water flow does not reach outlet feed nozzle, replace the pump motor.
II. EXCESS HUMIDITY
III. LEAKING WATER
● Reservoir and Pump Section
The Model 445, 445A and 448 are circulating units which will require maintenance
every 30 days. Complete servicing instructions for both the water reser-
voir and circulating pump are located in the homeowners manual.
Aprilaire Humidifier Control
APRILAIRE HUMIDIFI-
TRANSFORMER
(2 VA MINIMUM)
24 VAC
FURNACE
BLOWER
MODEL
50
CORD & PLUG
TO 120VAC
60Hz POWER
SUPPLY
GROUND
GREEN
IV. NOISE
● Pump Motor
a. Disconnect electrical power. Remove the motor board cover.
b. Check fan blade.
c. Oil with two drops SAE #20 oil in the yellow hole on top and inside the yellow
mark on the side of the motor.
V. GENERAL MAINTENANCE
— See Page 4.
NORTH, EAST
OR WEST SIDE
OF HOME
OUTDOOR
TEMPERATURE
SENSOR &
*
OUTDOOR
TEMPERATURE
ABOVE EXPECTED
SENSOR & LEADS
SNOW LINE
Note: for installation in manual mode, replace
*
outdoor temperature sensor with plastic resistor
case and attach manual face plate. See form
#DP10005402 for complete wiring instructions,
included with each humidifier.
YELLOW
YELLOW
RELAY
BLACK
TRANSFORMER
WHITE
PUMP
BLUE
MOTOR
— See Pages 4 and 5.
IMPORTANT
USE 120 VAC
POWER SOURCE
OTHER THAN
FURNACE
MOTOR CIRCUIT
HOWEVER THE
TRANSFORMER
CAN BE POWERED
OFF THE HOT 120V
LINE BEFORE IT
ENTERS THE
FURNACE.
YELLOW
CORD & PLUG
TO 120VAC
60Hz POWER
SUPPLY
BLACK
WHITE
GROUND
GREEN
- 17 -
Manual Humidistat
NOTE
SOME FURNACES ARE EQUIPPED
WITH ACCESSORY TERMINALS THAT
CAN BE USED FOR THE HUMIDIFIER.
THE RP MODEL 50 RELAY MAY NOT BE
NECESSARY IN THIS CASE. CONSULT
THE FURNACE MANFACTURER'S REC-
OMMENDATIONS FOR WIRING.
HUMIDISTAT
CURRENT SENSING
RELAY
COMMON
LEAD
24 VAC
LEADS
FURNACE
BLOWER MOTOR
YELLOW
RELAY
TRANSFORMER
BLUE