General Wiring; Burner Wiring; High Temperature Limit - Weil-McLain WGO 4 Series Manual

WGO
OIL-FIRED NATURAL DRAFT WATER BOILER — SERIES 4 —
Connect wiring

General wiring

• Packaged boilers have harnesses furnished.
• For Semi-packaged and Knocked-down boilers, trim kits
are furnished with burner and limit harnesses integrated
with Hydrolevel control.
• All field-provided high voltage wiring must be sheathed
in flexible metal conduit.
• Connect incoming line voltage "HOT" wire to service
switch, and neutral wire to white wire. Field-install equip-
ment ground wire to green wire with wire nut inside
Hydrolevel control.
• Service switch is integrated into the Hydrolevel control.
• Some local codes may require an emergency shut-off
switch installed at a location away from boiler. Follow
local codes.

Burner wiring

• Burner harness incorporates a disconnect plug, provid-
ing a convenient way to disconnect wiring when burner
mounting door is opened.
• All Packaged boilers have a power disconnect plug installed
on combination limit control.
• The burner is provided with a burner disconnect plug as
shown in Figure 18. For burners in which the disconnect
plug is not factory-wired, connect the threaded conduit
coupling of the disconnect plug wire harness (P/N 591-
391-850, included in water trim carton) to the burner
housing and route the wires to make all connections in
burner junction box as shown in boiler wiring diagram.

High temperature limit

• To comply with ASME, UL 726 or Canadian requirements,
an additional high temperature limit is needed.
• Install the secondary control in the supply piping between
boiler and isolation valve.
• Set the control to a minimum of 20˚F above the set point
of the combination control.
• The maximum allowable set point is 220˚F.
• Wire the control as shown on page 24.
THE LIMIT CONTROL SUPPLIED WITH THE BOILER MUST BE SET-UP WITH THERMAL PREPURGE
Section 303 of the
In accordance with
2007 Energy Act , this boiler is equipped
with a feature that saves energy by re-
ducing the boiler water temperature as
the heating load decreases. This feature
is equipped with an override which is
provided primarily to permit the use of
an external energy management system
that serves the same function.
Part number 550-142-331/0421
SERVICE TECHNICIAN ONLY — read and follow completely.
(continued)
OR THERMAL TARGETING ACTIVE UNLESS EXEMPTED BELOW:
IMPORTANT
THIS OVERRIDE MUST NOT BE USED UNLESS AT LEAST ONE OF THE
FOLLOWING CONDITIONS IS TRUE:
• An external energy management system is installed that reduces the boiler water tem-
perature as the heating load decreases.
• This boiler is not used for any space heating.
• This boiler is part of a modular or multiple boiler system having a total input of
300,000 BTU/hr or greater.
• This boiler is equipped with a tankless coil (not applicable to WGO boilers).
Boiler Manual
Figure 18
Boiler wiring for forced hot water
Limit control
Burner
wiring
harness
Burner
disconnect
plug
Service
switch
on
control
23