Part number 550-141-825/1211
18
GOLD
WTGO
OIL-FIRED NATURAL DRAFT WATER BOILER — SERIES 3 — Boiler Manual
SERVICE TECHNICIAN ONLY — read and follow completely.
Connect water piping
Boiler model
number
To system From system
WTGO-3 1¼" 1¼"
WTGO-4 1¼" 1¼"
WTGO-5 1½" 1½"
WTGO-6 1½" 1½"
WTGO-7 1½" 1½"
WTGO-8 2" 2"
WTGO-9 2" 2"
* All piping sizes based on 20°F
temperature rise through boiler.
Table 4 Water piping sizes
General piping information
• All packaged WTGO 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 allowable
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 Water Piping Size Table 4 for
near-boiler piping and single-zone piping. See page 20 to complete
multiple-zone piping or page 21 to complete piping for systems oper-
ating below 140°F.
• For multiple-boiler piping, refer to Weil-McLain’s “Primary/Secondary
Piping Guide.”
• 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)
• 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)
• 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 10
to expansion tank. Use ½" NPT piping. Pitch any
horizontal piping up towards tank 1 inch per 5
feet of piping.
To connect WTGO boilers to
indirect-fired water heaters
• Install and wire per water heater manual provided
with water heater.
• If boiler has a tankless heater installed:
• Remove tankless heater and install cover plate.
OR
• Leave tankless heater installed. Drain coil and re-
move piping. Do not plug holes in tankless heater
front plate.
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