Weil-McLain CGa 3 Series Manual page 17

CGa Series 3 Gas-Fired Water Boiler — Boiler Manual
3b
Water piping — single-zone system
Diaphragm-type or bladder-
type expansion tank
1. Ensure expansion tank size will handle boiler and
system water volume and temperature. Tank must
be located in boiler return piping as close to boiler
as possible, before inlet side of circulator. See tank
manufacturer's instructions for details.
2. Install an
Figure 9
Part Number 550-142-300/0520
Undersized expansion tanks cause system water to be lost from relief valve and makeup water
to be added through fill valve. Eventual section failure can result.
(Figure 9)
automatic air vent
as shown.
Figure 9 Figure 10
Use or
130°F.
For systems with low return water temperature possible, such as converted gravity
systems and radiant heating systems, refer to the special piping suggestions of pages 20-25.
Failure to prevent low return water temperature to the boiler could cause corrosion of the boiler
sections or burners, resulting in severe personal injury, death or substantial property damage.
Diaphragm- or bladder-type expan-
sion tank — Single-zone system using
diaphragm-type or bladder-type expan-
sion tank. See Table 3 for piping sizes.
Closed-type expansion tank
(Figure 10)
1. Ensure expansion tank size will handle boiler and
system water volume and temperature. See tank
manufacturer's instructions for details.
2. Connect tank to ½" NPT tapping located behind
supply outlet, using ½" NPT piping. Pitch any
horizontal piping up towards tank 1 inch per 5 feet
of piping.
only for single-zone systems designed for
Figure 10 Closed-type expansion tank — Single-
zone system using closed-type expan-
sion tank. See Table 3 for piping sizes.
return water at least
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