Boiler Manual
Part Number 550-110-593/1099 27
Field wiring
For your safety, turn off electrical power supply at
service entrance panel before making any electrical
connections to avoid possible electric shock hazard.
Failure to do so can cause severe personal injury or
death.

Electrical installation must

comply with:

1. National Electrical Code and any other national,
state, provincial or local codes or regulations.
2. In Canada, CSA C22.1 Canadian Electrical Code
Part 1, and any local codes.

Wiring connections

Boiler is shipped with controls completely wired, except
spill switch and vent damper. Refer to wiring diagrams
shown on page 34 for standing pilot ignition boiler or
page 38 for spark-ignited pilot boiler.
Figure 20
Field wiring connections —
service switch and
thermostat (or end switch)
provided by installer
5
Field wiring
Factory wiring
Service
switch
(notprovided)
Junction box,
boiler left side
Thermostat
leads, through
jacketleft side
Service
switch
(notprovided)
Thermostat
or end switch
(notprovided)
Thermostat
or end switch
(notprovided)
Black White Green
Ground screw Wire nuts
Black Black
120 VAC
Hot Neutral Ground
59323
Thermostat
1. Connect thermostat as shown on wiring diagram
on boiler.
2. Install on inside wall away from influences of drafts,
hot or cold water pipes, lighting fixtures, television,
sunrays or fireplaces.
3. If thermostat has a heat anticipator, set heat
anticipator in thermostat to match power
requirements of equipment connected to it. If
connected directly to boiler, set for 0.1 amps plus
gas valve current. See information on the wiring
diagram shown in Figure 25b, page 39. For other
devices, refer to manufacturer’s specifications.
Wiring diagram on boiler gives setting for control
module and gas valve. Also see instructions with
thermostat.
Junction box (furnished)
1. Connect 120 VAC power wiring (Figure 20).
2. Fused disconnect or service switch (15 amp.
recommended) may be mounted on this box. For
those installations with local codes which prohibit
installation of fused disconnect or service switch on
boiler, install a 2 x 4 cover plate on the boiler
junction box and mount the service switch remotely
as required by the code.
Wiring multiple zones
Refer to zone valve manufacturer’s literature for wiring
and application. A separate transformer is required to
power zone valves. Zoning with circulators requires a
relay for each circulator.
Wiring must be N.E.C. Class 1.
If rollout thermal fuse element wire as supplied with
boiler must be replaced, type 200 °C wire or equivalent
must be used. If other original wiring as supplied with
boiler must be replaced, use only type 105 °C wire or
equivalent.
Boiler must be electrically grounded as required by
National Electrical Code ANSI/NFPA 70-latest edition.