Operating instructions
34
8.1 General
Electrically bond boiler to ground in accordance with 
requirements of authority having jurisdiction. Refer to:
• USA- National Electrical Code, ANSI/NFPA 70.
• Canada - Canadian Electrical Code, Part I, CSA C22.1: 
Safety Standard for Electrical Installations.
8.2 Electric Knockouts (gure 8-1)
• Five knockouts located on bottom of chassis.
A.  Three knockouts located under junction box are 
reserved for high voltage wires. Choose connectors 
using total diameter of wire bundles.
B.  Two knockouts located to right of high voltage 
knockouts (outside of junction box) are reserved 
for low voltage wiring. Use supplied grommets 
when using these knockouts.
8.3 Line Voltage Connections (gure 8-2)
• Boiler
A.  Provide individual 120V, 15 amp circuit 
(recommended) with fused disconnect or service 
switch as required by authority having jurisdiction.
B.  Open High Voltage Junction Box (see gures 3-4 
and 3-5) to access line voltage terminal strip.
C.  Connect 120 VAC circuit to line voltage terminal 
strip 120 VAC L,N,G.
• Central Heating Pump, if used.
A.  Isolate pump from control module if pump FLA (Full 
Load Amps) exceeds maximum allowable current 
draw. See Figure 8-3 and Table 11.
B.  Connect pump to line voltage terminal strip CH 
PUMP L,N,G.
• Domestic Hot Water Pump, if used.
A.  Isolate pump from control module if pump FLA 
exceeds maximum allowable current draw. See 
Figure 8-3 and Table 11.
B.  Connect pump to line voltage terminal strip DHW 
PUMP L,N,G.
8.4 External Connections (gure 8-4)
• User Interface Terminals 
A.  Factory wired to USER INTERFACE terminals
B.  Optional - Remote mount user interface for 
improved access. Use low voltage knockout. 
C.  Maximum wire length is 100 ft (30m) for 22 ga. 
wire, or 150 ft (45m) for 18 ga. wire.
WARNING
Electrical shock hazard. Turn OFF electrical power 
supply at service panel before making electrical 
connections. Failure to do so could result in death 
or serious injury.
! 
FIGURE 8-2 Line Voltage Connections
NOTICE
Wiring diagrams can be found in Section 14 of this 
Manual.
FIGURE 8-1 Electric Knockouts Bottom Of Boiler
 4½"
(114mm)
 5"
(127mm)
High Voltage 
Knockouts
Low Voltage Knockouts
(Use supplied 
grommets when using 
these knockouts)
Front of Boiler
Back of Boiler
8 - ELECTRICAL CONNECTIONS
MBH CH PUMP DHW PUMP NOTE
50 
75 
100
1 A 1 A
Powered by 
Control Board
150 
200 
299
10 A 10 A
Powered by 
installed 10 Amp 
relay
If CH or DHW pump current is more than the maximum 
allowable current draw install proper eld sourced relays 
as shown in gure 8-3.
Table 11 - Maximum Allowable Current Draw










