SERVICE TECHNICIAN ONLY — read and follow completely.
Connect water piping
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, an additional high
temperature limit is needed. If installation is to comply with
Canadian requirements, an additional high temperature limit
maybe needed. Consult local inspector. Install control in sup-
ply piping between boiler and isolation valve. Set control to
a minimum of 20°F above set point of combination control.
Maximum allowable set point is 220°F. Wire control as shown
on wiring diagram.
•
Use back flow check valve in cold water supply as required
by local codes.
Install piping
•
See Figures 11 or Figure 12, page 19, and Table 4 for near-
boiler piping and single-zone piping. See page 20 to com-
plete multiple-zone piping or page 21 to complete piping for
systems operating below 140°F.
•
For multiple-boiler piping, contact Weil-McLain Technical
Services for assistance, if required.
•
Install relief valve vertically in “R1” tapping on front of boiler.
See Figure 11 or Figure 12 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 oc-
cur. Do not plug, valve or place any obstruction in
discharge line.
DIAPHRAGM expansion tank
(
Figure 11, 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 Fig-
ure 11.
CLOSED expansion tank
(
Figure 12, 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 re-
sult.
•
Connect tank from “N” tapping shown in Figure 12, page 19
to expansion tank. Use ½" NPT 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.
Table 4
Water piping sizes
Boiler
Size
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
Part number 550-142-331/0421
18
WGO
OIL-FIRED NATURAL DRAFT WATER BOILER — SERIES 4—
Boiler Manual
