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Part number 550-110-260/0508
15
GOLD CGs Gas-Fired Water Boiler — Boiler Manual
Water piping — single-zone system3b
Figure 4 Diaphragm- or bladder-type expansion tank
Piping to single-zone system
See Table 3 for piping sizes.
Figure 5 Closed-type expansion tank
Piping to single-zone system
See Table 3 for piping sizes.
Diaphragm-type or bladder-
type expansion tank (Figure 4)
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
automatic air vent in air vent tapping as
shown.
Closed-type expansion tank
(Figure 5)
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.
Undersized expansion tanks cause system water to be lost from relief valve and makeup water
to be added through fi ll valve. Eventual section failure can result.
Use Figure 4 or Figure 5 only for single-zone systems designed for return water at least 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 18-23. 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.