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Part number 550-142-054/0411
GV90+ gas-fired water boiler — Boiler Manual
56
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.
Installation must comply with:
National Electrical Code and any other national, state, provincial or
local codes or regulations. In Canada, CSA C22.1 Canadian Electrical
Code Part 1, and any local codes. Boiler must be electrically grounded as
required by National Electrical Code ANSI/NFPA 70-latest edition.
Wiring must be N.E.C. Class 1. Boiler must be electrically
grounded as required by National Electrical Code ANSI/
NFPA 70-latest edition.
To replace wiring, order complete harness assemblies
from Weil-McLain. If any original wiring as supplied with
boiler must be replaced, and a harness is not immediately
available, use only type 105°C wire or equivalent. Use this
wiring only as a temporary repair. Obtain a complete
harness from Weil-McLain.
Wiring connections
Power wiring
Connect 120 VAC power wiring as shown in Figure 66. The junction
box is located on the inside left jacket panel.
Watch the polarity of the circuit when connecting the
120 VAC power wiring. If the polarity is switched, the
integrated boiler control will lockout. The IBC will
flash the POWER light to indicate this problem. See the
troubleshooting information beginning on page 75.
Additional limit controls
Wire additional limit controls (if used) as shown in Figure 67.
Thermostat(s)
Install thermostats on inside walls, away from influences of drafts,
hot or cold water pipes, lighting fixtures, television, sun rays, or fire-
places.
Follow instructions with thermostat. If it has a heat anticipator, set heat
anticipator in thermostat to match power requirements of equipment
connected to it (ignition control and gas valve, zone valve contacts,
etc.). Wiring diagram on boiler gives setting for standard equipment
(ignition control and gas valve).
Thermostat wires are labeled “T-T” on boiler. Remove label before
connecting as shown in Figure 66. Route this wiring through the hole
in the upper left side jacket.
For zoned systems, substitute the zone valve end switches or circulator
relay contacts for the thermostat contact shown in Figure 66.
Figure 66 Field wiring connections — service switch
and thermostat (or end switch) provided
by installer
When using three-wire zone valves, take care
to avoid mis-wiring. This can impose an ad-
ditional 24 volts across the boiler control circuitry. The IBC
will sense this problem and lockout. It will flash the POW-
ER and TSTAT CIRC lights to indicate the problem. See
label on IBC for explanation of lockout conditions. To
verify before connecting to boiler, disconnect field thermo-
stat wires at boiler. Place a voltmeter across the leads. Then
watch the voltmeter as each zone is activated (by activating
zone thermostat). There should never be a voltage reading
across the two leads coming to the boiler. If you see a volt-
age reading, one or more zone valves is mis-wired.
Carbon monoxide detector
For Direct Exhaust units, a carbon monoxide
detector is required in the boiler room. The
carbon monoxide detector must be wired on
the same electrical circuit as the boiler. For
Direct Vent units, a carbon monoxide detector
that is wired on the same electrical circuit as
the boiler is strongly recommended.
Figure 67 Wiring location for additional limit controls