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WIRING AND OPERATION
All wiring should be installed according to local and national electrical codes and ordinances.
Figure 4 shows wiring connections for a typical installation using
the 8J48A with a 36C03 or a 36C53 24V manifold gas valve.
Figure 5 shows wiring connections for the 8J48A with a 36C03U
or 36C53U self-generating gas valve. Operation is as follows:
As the room thermostat contacts close, the relay coil is ener-
gized and closes its two sets of relay contacts. The manifold gas
valve opens as the no. 1 relay contacts close, while the circulator
motor starts as the no. 2 relay contacts close.
When the room thermostat opens its contacts, the manifold gas
valve closes and the circulator motor stops.
If the boiler temperature exceeds the setting of the high limit
while the thermostat is calling for heat, the high limit will close the
gas valve but permit the circulator to run as long as the
thermostat is calling for heat.
AUTO/MANUAL SWITCH
For manual operation of self-generating millivolt systems
only.
The manual switch, located on the outside of the controls case,
allows operation of the burner during power failures. When the
switch is set to MANUAL, the burner will operate continuously
until the high limit temperature is reached. The circulator, which
requires line voltage to operate, will not function in MANUAL
mode. When power is restored, reset the switch to AUTO to
resume automatic operation.
NOTE
C1
C2
T
TV
B3
B1
Z W TP
B2
B
120 VAC
Transformer
Factory-
installed
Jumper
Field-
installed
Jumper
Manual
Switch
High
Limit
No. 1 Relay
Contacts
36C
Gas Valve
Low Voltage
Room Thermostat
Circulator
Motor
No. 2 Relay
Contacts
Hot
Neutral
TH TH-TR TR
Line Voltage
Low Voltage
INTERNAL WIRING
Line Voltage
Low Voltage
EXTERNAL WIRING
Figure 4. 24 Volt AC Gas Valve
L1
L2
C1
C2
T
TV
B3
Z W TP
B2
B
120 VAC
Transformer
Factory-
installed
Jumper
Manual
Switch
High
Limit
No. 1 Relay
Contacts
36C
Gas Valve
To 750 MV
Thermopile
Low Voltage
Room Thermostat
Circulator
Motor
No. 2 Relay
Contacts
Hot
Neutral
TH TH-PG PG
Line Voltage
Low Voltage
INTERNAL WIRING
Line Voltage
Low Voltage
EXTERNAL WIRING
Figure 5. Millivolt Gas Valve
L1
L2
B1