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TO CONTROL
PANEL
W
R
B
W R
B
HI-LIMIT
AQUASTAT
RETURN
BURNER CONTROL
GATE VALVE
LOW WATER
CUTOFF
HON. RW700
OR EQUIV.
MANUAL
RESET
HI-LIMIT
SUPPLY WATER
TEMP. SENSOR
H3A
N
H2A
N
#2
#1
SUPPLY
115/24V
XFRMR.
DUAL AQUASTAT
AIR VENT
REVERSE ACTING AQUASTAT
H1
N
N.O.
N.C.
COM.
2" MOTOR
VALVE
#3
N H1
H2 H2
NO C
IN COM COM 24
VAC
AA
HEAT STARTER
240
VAC
COM
120
VAC
Y
TRANSFORMER
AR
RESET
S
STAGE
S
STAGE
240
NC COM NO
NC COM NO
AC
COM 120 NC
C
NO
SENSOR
SUPPLY
SENSOR
D.A.
SENSOR
COM
OUTSIDE AIR SENSOR
SUPPLY WATER SENSOR
OUTSIDE
AIR SENSOR
L1
L2
B
B
#1
DISPLAY
MODULE
(OPTIONAL)
DOUBLE POLE
RELAY WITH
115 COIL
TO CIRCULATOR
CONTACTOR COIL
#2
#3
115V LINES FROM
FUSED DISCONNECTS
POWER DISTRIBUTION
WIRING
D
DISPLAY
PRESS FOR SETPOINT
1
1
8
8
0
0
REQUIRED:
AA HEAT STARTER
OR
EQUIV. AUTOMATIC
CONTROL (T6031A)
OR
MANUAL SWITCH
(TO AVOID BOILERS
FIRING WITHOUT
CIRCULATOR
OPERATION)
H3A
BOILER
ROOM
SWITCH
MANUAL
RESET
HIGH LIMIT
LOW
WATER
CUTOFF
H2A
FIGURE C6: EXAMPLE OF LEVEL II CONTROL FOR COMBINATION SPACE & SERVICE WATER HEATING
Two modules maintain domestic hot water by modulating aquastats mounted in the heat exchanger for year-round operation. When the outdoor temperature falls below the setting of the heat starter mod-
ule, the circulator is energized. The reset module will fire the first module to maintain the supply water temperature according to the setting of the control. As the outdoor temperature decreases below
the setting of the stage modules, additional modules will fire. As the outdoor temperature decreases below the setting of the last stage module, the motorized valve will open, allowing domestic hot water
modules to contribute to space heating. If the water temperature in the heat exchanger falls below the setting of the low limit aquastat, the motor valve will close, retaining all the capacity in the heat
exchanger for domestic hot water.
SUPPLY
LOW LIMIT AQUASTAT
MOTORIZED
VALVE
L2
B
B
L1
ELECTRONIC
LOW WATER
CUTOFF
B
W
R
B
W
R
MANUAL RESET
HI-LIMIT
CIRCULATOR
SAFETY
HI-LIMIT
115V
24V TRANS.
SINGLE AQUASTAT
MODEL "S" CONTROL
FOR WIRING CONNECTIONS,
FOLLOW INSTRUCTIONS
IN S2 INSTALLATION MANUAL
PACKAGED WITH CONTROL
OUTDOOR
TEMP. SENSOR
RETURN
HN
115V
SUPPLY WATER
TEMP. SENSOR
TO "S"
CONTROL
TO "S"
CONTROL
TO "S"
CONTROL
DUAL AQUASTAT
POWER GAS BURNER
TO "S" CONTROL
TO
DISTRIBUTION
PANEL
FIGURE C7: EXAMPLE OF LEVEL III CONTROL FOR COMBINATION SPACE & SERVICE WATER HEATING
Three modules maintain domestic hot water by modulating aquastats mounted in the heat exchanger for year-round operation. When outdoor temperature falls below the setting of the outdoor
temperature sensor, the circulator and Model “S” control circuits are energized. The Model “S” control will begin to step fire modules until sufficient water temperature is present at the supply
water temperature sensor to meet the demand of the Model “S” control. When the heating load is great enough to operate Step 8 of the Model “S” control, the motorized valve will open, allowing
the domestic hot water modules to contribute to the space heating. If the water temperature in the heat exchanger falls below the setting of the low limit aquastat, the motorized valve will close,
retaining all of the capacity of the heat exchanger for domestic hot water.