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11.2.7 Checking the expansion vessel
Fig. 28
Checking expansion vessel
- Isolate the electrical supply.
- Isolate the boilers heating flow and return.
- Remove the boiler front casing cover.
- Drain the boiler until there is no pressure within the boiler.
- Remove the dust cover on the schreder valve located at the top of the expansion
vessel.
- Check the pressure within the vessel and if it requires increasing then connect a
suitable pump to the schreder valve and increase to a suitable pressure as indi-
cated
in Table 04.
- Refit the dust cover and recharge the boiler with cold water to a minimum of 0.8 bar
pressure.
- Open any isolating valves to the heating flow and return.
- Switch on the electrical supply to the boiler and test fire visually examining for
leaks.
- Re-fit front casing cover replacing the gasket if it was damaged during removal.
Note:
If the pressure gauge located in the boiler increases sharply when firing and
drops when not firing then the expansion vessel could be too small for the volume of
water in the heating system and an additional vessel will have to be installed.
