Install Instructions
40
5 Electrical connections
External EMS connection to terminal
strip for stage firing control of
burners
This unit is equipped with a factory installed terminal strip
for connection of an energy management system (EMS)
to the burner stages. The EMS terminal strip is located
in the unit’s control panel. Ensure that all wiring used
for connection to this terminal strip is properly sized per
the recommendations in TABLE 5A. When connecting
an EMS to this terminal strip to sequence on each stage
of burner operation, the unit’s internal thermostat or
electronic sequencer should be set as an additional high
limit control. This will prevent problems between the set
points of the EMS and the boiler’s internal controller.
wiring connections. This remote ON/OFF control will provide
an Enable/Disable signal to the unit and allow the unit to
operate based on the stage set points, until the remote ON/
OFF signal is cancelled.
Figure 5-7 shows the connections necessary to operate the
unit as a two-stage (High/Low Fire) boiler or water heater
from an Energy Management System (EMS). The actual set
point temperatures are controlled by the EMS. The High Fire
Offset on the electronic temperature control in the unit must
be set to zero and the set point must be set to a value which
will function as an upper limit for proper operation under this
two-stage control from an EMS.
Figure 5-8 shows the Continuous and Intermittent terminals.
External safety devices connected to these terminals will
function to protect the unit. Devices connected to the
Intermittent terminals (B1 and B2) are monitored only
when there is an active Call for Heat. Devices connected
to the Continuous terminals (A1 and A2) are monitored
continuously and will activate an alarm (if the unit is equipped
with the alarm option) anytime the safety device senses an
abnormal condition.
1
2
3
4
5
6
7
8
9
10
+
+
+
+
+
+
+
+
+
+
SYSTEM/TANK
SENSOR
B2
B1
A2
A1
2NO
2C
1NO
1C
INTERMITTENT
LIMITS
CONTINUOUS
LIMITS
HIGH FIRE
ENABLE
LOW FIRE
ENABLE
9
8
7
6
4
3
2
1
10 5
1
2
3
4
5
6
7
8
9
10
+
+
+
+
+
+
+
+
+
+
SYSTEM/TANK
SENSOR
B2
B1
A2
A1
2NO
2C
1NO
1C
INTERMITTENT
LIMITS
CONTINUOUS
LIMITS
HIGH FIRE
ENABLE
LOW FIRE
ENABLE
9
8
7
6
4
3
2
1
10 5
Remote
on/off
Figure 5-3_Stand-alone operation boiler
Figure 5-5_Remote on/off boiler
Installation & Service Manual
Line voltage connections
1. Connect 120 VAC power wiring to the line voltage
terminal strip in the junction box, as shown in FIG. 5-2.
2. Provide and install a fused disconnect or service switch
(15 AMP recommended) as required by the code (see
FIG. 5-2).
3. To activate a system pump, wire as shown in FIG. 5-2.
If the motor is larger than 1 HP, you must install a
contactor.
IMG00594
G
D
I
S
C
O
N
N
E
C
T
LN
120V
SUPPLY
UNIT
PUMP
1 HP MAX
LBL20174 REV A
UNIT
PUMP
D
I
S
C
O
N
N
E
C
T
G
NLNL
UNIT
SUPPLY
UNIT PUMP
SUPPLY
GROUND
SPLICE
CHASSIS
GROUND
Figure 5-2_Line Voltage Field Wiring Connections
Terminal strip connection options
Figures 5-3 and 5-4 show the position of jumpers as shipped
from the factory for stand-alone operation of boilers or
water heaters.
Figures 5-5 and 5-6 show connections to the terminal strip
for Remote ON/OFF control of the boiler or water heater.
The 1C-1NO jumper must be removed when making these
1
2
3
4
5
6
7
8
+
+
+
+
+
+
+
+
SYSTEM/TANK
SENSOR
B2
B1
A2
A1
NO
C
1
1
INTERMITTENT
LIMITS
CONTINUOUS
LIMITS
ENABLE
9
8
7
6
4
3
2
1
10 5
Figure 5-4_Stand-alone operation water heater