Page 279 - The City and Guilds Textbook: Plumbing Book 1 for the Level 3 Apprenticeship (9189), Level 2 Technical Certificate (8202) and Level 2 Diploma (6035)

Chapter 5 Cold water systems

Indirect boosting to a storage cistern

This system incorporates a break cistern to store the water before it is pumped
via a boosting pump (known as a booster set) to a storage cistern at high level.
The pumps should be fitted to the outlet of the break cistern. The capacity of
the break cistern needs careful consideration and will depend upon the total
water storage requirements and the cistern’s location within the building, but it
should not be less than 15 minutes of the pump’s maximum output. However,
the cistern must not be oversized as this may result in water stagnation within
the cistern.

The water level in the storage cistern (or cisterns) is usually controlled by means
of water level switches that control the pumps. When the water drops to a
predetermined level, the pumps start to fill the storage cisterns. The pumps are
then switched off when the water level reaches a point about 50 mm from the
shut-off level of the float-operated valve. A water level switch should also be
positioned in the break cistern to automatically shut off the pumps if the water
level drops to within 225 mm of the suction connection near the bottom of the
break cistern. This is simply to ensure the pumps do not run dry.

Pump stop
Pump stop Pump start
Pump start

NOTE: This drawing does not show any additional backflow
prevention devices that may be required under the Water
Supply (Water Fittings) Regulations 1999.

Filtered air vent
Incoming supply
Overflow and filter

Pump stop
Pump start

Duplicate pump
p Figure 5.28 Indirect boosting to a storage cistern

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