Weil-McLain 550-141-826/1201 - Manual (Page 18)

SERVICE TECHNICIAN ONLY — read and follow completely.
General piping information
• All packaged WGO boilers are shipped with an installed
combination temperature limit control/low water cut-off.
• If installation is to comply with ASME or Canadian
requirements, an additional high temperature limit is
needed. Install control in supply piping between boiler
and isolation valve. Set control to a minimum of 20°F
above set point of combination control. Maximum al-
lowable set point is 220°F. Wire control as shown on
wiring diagram.
• Use backflow check valve in cold water supply as required
by local codes.
Install piping
• See Figure 9 or Figure 10, page 19, and Table 4, page 18
for near-boiler piping and single-zone piping. See page 20
to complete multiple-zone piping or page 21 to complete
piping for systems operating below 140°F.
• For multiple-boiler piping, refer to Weil-McLain’s “Pri-
mary/Secondary Piping Guide” and “M-WGO Multiple
Boiler Manual.”
• Install relief valve vertically in “R1” tapping on front
of boiler. See Figure 9 or Figure 10 and also refer to tag
attached to relief valve for manufacturer’s instructions.
Pipe relief valve discharge line near floor close
to floor drain to eliminate potential of severe
burns. Do not pipe to any area where freezing
could occur. Do not plug, valve or place any
obstruction in discharge line.
DIAPHRAGM expansion tank
(Figure 9, page 19)
• Make sure expansion tank size will handle boiler and
system water volume and temperature. Tank must be
located near boiler before inlet to circulator. See tank
manufacturer’s instructions for details.
• Undersized expansion tanks cause system water to be lost
from relief valve and makeup water added through fill
valve. Eventual section failure can result.
• Install automatic air vent in “N” tapping as shown in
Figure 9.
CLOSED expansion tank
(Figure 10, page 19)
• Ensure expansion tank size will handle boiler and
system water volume and temperature.
Undersized expansion tanks cause system
water to be lost from relief valve and
makeup water added through fill valve.
Eventual section failure can result.
• Connect tank from “N” tapping shown in Figure
9 to expansion tank. Use ½" N.P.T. piping. Pitch
any horizontal piping up towards tank 1 inch per
5 feet of piping.
To connect WGO boilers to
indirect-fired water heaters
Install and wire per water heater manual provided with
water heater.
Connect water piping
Boiler model
number
To system From system
WGO-2 1" 1"
WGO-3 1¼" 1¼"
WGO-4 1¼" 1¼"
WGO-5 1½" 1½"
WGO-6 1½" 1½"
WGO-7 1½" 1½"
WGO-8 2" 2"
WGO-9 2" 2"
* All piping sizes based on 20°F
temperature rise through boiler.
Table 4 Water piping sizes
Part number 550-141-826/1211 18
GOLD
WGO
OIL-FIRED NATURAL DRAFT WATER BOILER — SERIES 3 —
Boiler Manual