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Part Number 550-142-300/0520
27
CGa Series 3 Gas-Fired Water Boiler — Boiler Manual
For your safety, turn off electrical power supply at ser-
vice entrance panel before making any electrical con-
nections
to avoid possible electric shock hazard. Failure
to do so can cause severe personal injury or death.
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.
Installation must comply with:
1. National Electrical Code ANSI /NFPA 70 – latest edition
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 36 for spark-ignited pilot boiler.
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 equip-
ment 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 37.
For other devices, refer to manufacturer’s specifica-
tions. Wiring diagram on boiler gives setting for
control module and gas valve. Also see instructions
with thermostat.
DHW
Connect DHW aquastat as shown in wiring below.
Economy function isn’t utilized with DHW input.
Junction box (furnished)
1. Connect 120 VAC power wiring (Figure 20).
2. Fused disconnect or service switch (15 amp. recom-
mended) may be mounted on this box. For those
installations with local codes which prohibit instal-
lation 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.
DO NOT connect directly from 3-wire
zone valves to the T-T terminals on
the boiler
. When using 3-wire zone
valves, install an isolation relay. Connect
the zone valve end switch wires to the
isolation relay coil. Connect the isolation
relay contact across the boiler T-T
terminals. Failure to comply can result in
damage to boiler components or cause
unreliable operation, resulting in severe
property damage.
Field wiring
Figure 20
Field wiring connec-
tions —
service switch, DHW
(if used) and
thermostat
(or end switch) pro-
vided by installer
5
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