Honeywell H8908B Humidistat Installation Instructions page 3

WIRING
CAUTION
Personal Injury Hazard.
Power supply can cause electrical shock and
injury.
Disconnect power supply before installation or
servicing.
All wiring must comply with applicable local codes, ordi-
nances and regulations. Make wiring connections
according to humidifier (or dehumidifier/ventilator)
instructions, if available; otherwise, see typical wiring
diagrams in Fig. 5 through 12.
IMPORTANT
Select models of fan centers include humidifer
taps so the current sensing relay or sail switch
is not needed.
If not using a current sensing relay or sail
switch, the humidifier must be energized dur-
ing blower motor cycles for proper operation.
On multispeed blower applications, do not wire
the high voltage side of the transformer to the
same power source that services the furnace
blower. Premature transformer burnout can
occur.
On HE360 fan powered humidifier models,
only the two yellow wires are connected to the
control. The remaining two red wires are only
used with electronic humidity controls.
L1
(HOT) POWER
FAN CONTROL
SUPPLY
L2
1
FURNACE
FAN
MOTOR
1 PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION
AS REQUIRED.
2 24 VAC WIRING.
Fig. 5. Typical wiring diagram for
system with fan interlock.
L1
(HOT) POWER
FAN CONTROL
SUPPLY
L2
DPST
1
SWITCHING
RELAY
H L
C
1 POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
2 24 VAC WIRING.
Fig. 6. Typical wiring diagram for system
with 2-speed fan motor.
H8908B
TRANSFORMER
HUMIDIFIER
H8908B
2
TRANSFORMER
2-SPEED
FAN
HUMIDIFIER
MOTOR
H8908B HUMIDISTAT H8908C DEHUMIDISTAT
CURRENT
SENSING
RELAY
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
2 24V WIRING.
Fig. 7. Typical wiring diagram of current
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
2 24V WIRING.
H8908B
2
1 24V WIRING.
NOTE:
Fig. 9. Typical wiring diagram for steam humidifiers.
M13368
H8908C
1 PROVIDE OVERLOAD PROTECTION AND
DISCONNECT MEANS AS REQUIRED.
M13384
Fig. 10. Typical parallel wiring of humidity controller
with Chronotherm® IV Thermostat for
dehumidification and mildew control.
3
H8908B
2
TRANSFORMER
1
L2 L1
(HOT)
LO
C
HI HUMIDIFIER
sensing relay with humidifier.
SAIL
SWITCH H8908B
2
TRANSFORMER
1
L1
L2
(HOT)
Fig. 8. Typical wiring diagram
of sail switch with humidifier.
FAN WIRING
TERMINALS
1
HUMIDISTAT
TERMINALS
HUMIDIFIER
FOLLOW THE INSTALLATION INSTRUCTIONS
INCLUDED WITH THE STEAM HUMIDIFIER
TO WIRE THE SYSTEM FAN.
CHRONOTHERM ® IV THERMOSTAT
B O
W Y
HEATING
RELAY OR
VALVE COIL
COOLING
CONTACTOR
COIL
WATER
SOLENOID
LEAD WIRE
M13386
HUMIDIFIER
M13385
1
TO
SYSTEM
FAN
M13387
R
G
FAN
RELAY
COIL
1
M13366
69-1341