11 68-0173—3
Fig. 13. Hookup diagram for heating/cooling intermittent pilot gas burning ignition system.
S1
S
T1
T
OUT
OUT
LED
G
Y2
Y1
W1
W2
1
2
3
4
GND
C
R
RH
RC
HUM
HUM
VNT
VNT

W8900A,C

L1
(HOT)
L2
1
3
4
2
1
2
3
4
5
5
POWER SUPPLY. PROVIDE DISCONNECT
MEANS AND OVERLOAD PROTECTION
AS REQUIRED.
JUMPER R TO RH TO RC FOR SINGLE
TRANSFORMER APPLICATIONS.
DURING INSTALLER SETUP, CONFIGURE PC8900 FOR HUMIDITY CONTROL IN HEATING MODE
(HUMIDIFIER) OR COOLING MODE (DEHUMIDIFIER).
W8900 ALLOWS CONNECTION OF A CO MONITOR WITH UNCOMMITTED CONTACTS.
SEE VENTILATION INSTRUCTIONS FOR WIRING.
GROUNDING THE GND TERMINAL IS NOT RECOMMENDED.
CONNECTION FOR CM8900A REMOTE COMMUNICATIONS MODULE.
STAGE 1
COOL RELAY
FAN RELAY

PC8900

1
2
3
4
CO
2
MONITOR
M4489D
S8610U
MV MV/PV PV
GND
(BURNER)
24V
GND 24V TH-W
VENT
DAMPER
PLUG SENSE SPARK
LIMIT
CONTROLLER
PILOT
BURNER
GROUND
SENSOR
IGNITER
MAIN
VALVE
COM
PILOT
DUAL VALVE COMBINATION
GAS CONTROL
PILOT GAS
SUPPLY
1ST
OPERATOR
2ND
OPERATOR
D892 VENT
DAMPER
HUMIDIFIER OR
DEHUMIDIFIER
EQUIPMENT
VENTILATION
EQUIPMENT
CO
2
SYSTEM
TRANSFORMER
C7189A REMOTE AIR
TEMPERATURE SENSOR
C7100 DISCHARGE AIR
TEMPERATURE SENSOR
C7089A OUTDOOR AIR
TEMPERATURE SENSOR
2
7
6
7
6