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Part Number 550-110-710/0107
21
GOLD CGi Gas-Fired Water Boiler — Boiler Manual
Water piping — single-zone system4b
Diaphragm-type or bladder-
type expansion tank (Figure 16)
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 as shown.
Figure 16 Diaphragm- or bladder-type expansion
tank — Piping to single-zone system
using diaphragm-type or bladder-type
expansion tank. See Table 6 for piping
sizes.
Figure 17 Closed-type expansion tank — Piping
to single-zone system using closed-
type expansion tank. See Table 6 for
piping sizes.
Closed-type expansion tank
(Figure 17)
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.
Use Figure 16 or Figure 17 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 24-29. 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.
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.