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Universal Control System – Natural gas
Part Number 550-141-916/1001 7
Figure 3
Wiring diagram
Universal Control System
Natural Gas
LGB
6 thru 23
Intermittent Pilot
Steam or Water
550-101-131/0798WM
Michigan City, IN 46360-2388
A United Dominion Company
500 Blaine St.
PART NUMBER
Weil-McLain
(WHEN USED)
(NOTE 5)
HIGH GAS
PRESSURE
SWITCH
R
H
(NOTE 9)
(WHEN USED)
FIRING RATE CONTROL
PILOT BURNER
MAIN FLAME SENSOR
MAIN GAS VALVE LOW FIRE OPERATOR
MV/PV
PRESSURE
HIGH GAS
SENSE
SPARK
SWITCH
GND
(BURNER)
24V
(GND)
1
24V
PV
PILOT FLAME SENSOR
MV
NO. 2 BASE
MAIN FLAME PROVING MODULE
SPARK
SENSE
24V
GND
(BURNER)
PV
MV/PV
(GND)
24V
PILOT PROVING MODULE
SPARK
NO. 1 BASE
SENSE
(GND)
GND
(BURNER)
24V
1
24V
MV
PILOT FLAME SENSOR
PILOT SOLENOID VALVE
2
PV
MV/PV
(NOTE 6)
MAIN GAS VALVE HIGH FIRE
OPERATOR (NOTE 6)
MV
MV/PV
2
(WHEN USED)
FIRING RATE CONTROL
MAIN FLAME SENSOR
LADDER WIRING DIAGRAM
MAIN GAS VALVE LOW FIRE OPERATOR
CONTROL
CUT-OFF
CONTROL
(BY OTHERS)
MV
PV
MV/PV
NO. 1 BASE
MAIN FLAME PROVING MODULE
SPARK
SENSE
(BURNER)
GND
PV
24V
(GND)
24V
R
24 V.A.C.
MV
MV/PV
24 V.A.C.
PRIMARY
PRIMARY
SERVICE SWITCH
OPERATING
LOW WATER
120 V.A.C.
HIGH
LIMIT
PILOT SOLENOID VALVE
SECONDARY GAS VALVE
PV
MV/PV
(NOTE 6)
OPERATOR (NOTE 6)
MAIN GAS VALVE HIGH FIRE
MV
MV/PV
C
N
GROUND
(NOTE 10)
EQUIPMENT
PILOT BURNER
(NOTE 9)
(WHEN USED)
PILOT PROVING MODULE
(NOTE 5)
NO. 2 BASE
PV MV/PV
SECONDARY GAS VALVE
MV/PVPV