21
Part Number 550-142-320/0720
GWA
Series 3
Gas-Fired Water Boilers –
Boiler Manual
6 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.
Wiring must be NEC Class 1– latest edition.
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.
Electrical installation must comply with:
National Electrical Code - latest edition and any other national,
state, provincial or local codes or regulations.
Wiring connections
Boiler is shipped with controls completely wired, except spill
switch and vent damper. See wiring diagram on pages 28
& 29
for spark-ignited pilot boiler. Circulator is shipped loose, but
wiring harness is pre-attached to the boiler. Connect wires in
circulator junction box.
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, sun rays 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 0.4
Figure 18
Field wiring connections - service switch, DHW (if used) and thermostat (or end switch) provided by installer.
amps. For other devices, see manufacturer’s specifications.
Wiring diagram on boiler gives setting for control module
and gas valve. Also see instructions with thermostat.
DHW
(if used)
Connect DHW aquastat as shown in wiring below. Economy
function isn’t utilized with DHW input.
R & C Connections
(if used)
24 VAC leads should be used for power stealing thermostats
only!
Junction box
1. Connect 120 VAC power wiring (Figure 18).
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
See zone valve manufacturer’s literature for wiring and applica-
tion. 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.
