Models 220-224-400*-440-550-550A*-558*-560-560A*-568*-600 - Aprilaire 220 Service Manual

INDIVIDUAL UNIT SERVICE—MODELS 220-224-400-440-550-550A-558-560-560A-568-600
CAUTION:
1. Sudden operation may cause personal injury or property damage. Turn
the Automatic Humidifier Control or manual humidistat to "Off" or
lowest setting before servicing or troubleshooting these units.
I. LACK OF HUMIDITY
●
Check The Home — See Pages 2 and 3.
●
Check Furnace Operation — See Page 3.
●
Check The Humidity Control — See Page 4.
●
General Maintenance — See Pages 4 and 5.
1. AIR FLOW — Be sure the damper in the duct between the two plenums is open. Air
flow is based on a 0.2 total static pressure difference between the supply and return
plenums. The static pressure can be determined with a U-Tube Manometer calibrated in
inches of water. Adjust the damper to obtain proper air flow at pressures greater than 0.2
inches of water.
2. ELECTRICAL COMPONENTS — The transformer must be isolated from multispeed
motors with an RP Model 50 Current Sensing Relay. All components should be tested in
place making sure all electrical connections are secure and there are no breaks in the
service. If the solenoid valve isn't working with the humidistat circuit closed (see dia-
gram) and the furnace blower is running, disconnect electrical power and insert a trans-
former that is known to function and check. If the solenoid valve functions, replace the
transformer. If the solenoid valve does not function, replace the valve.
Note: With the Model 400, both floats must be in the down position for electrical con-
nection.
Aprilaire Humidifier Control
TRANSFORMER
(10 VA MINIMUM)
24 VAC
FURNACE
BLOWER
MODEL
50
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.
II. EXCESS HUMIDITY
NORTH, EAST OR
WEST SIDE OF HOME
OUTDOOR
TEMPERATURE
SENSOR & SHIELD
*
OUTDOOR
ABOVE EXPECTED
TEMPERATURE
SNOW LINE
SENSOR & LEADS
LEADS
TO APRILAIRE
TERMINALS
DO NOT WIRE
SOLENOID LEADS
TO EXTERNAL
24 VAC SOURCE
— See Page 4.
Manual Humidistat
IMPORTANT
CURRENT SENSING
USE 120 VAC
RELAY
POWER SOURCE
OTHER THAN FURNACE
MOTOR CIRCUIT
HOWEVER THE
TRANSFORMER
CAN BE POWERED
OFF THE HOT
FURNACE
120V LINE BEFORE IT
BLOWER MOTOR
ENTERS THE
FURNACE.
24 V
120 V
TRANSFORMER
- 6 -
NOTE
SOME FURNACES
ARE EQUIPPED
WITH ACCESSORY
TERMINALS THAT
COMMON
LEAD
CAN BE USED FOR
THE HUMIDIFIER.
THE RP MODEL 50
RELAY MAY NOT BE
NECESSARY IN THIS
CASE. CONSULT
THE FURNACE
HUMIDISTAT
MANFACTURER'S
RECOMMENDA-
TIONS FOR WIRING.
SOLENOID
VALVE