Page 298 - The City and Guilds Textbook: Plumbing Book 1 for the Level 3 Apprenticeship (9189), Level 2 Technical Certificate (8202) and Level 2 Diploma (6035)

The City & Guilds Textbook: Plumbing Book 1

Service valve
Independent screened
Cold water supply
overflow pipes for each
cistern. Cisterns over 1000
litres require an overflow and
a warning pipe

Service valve

Access cover for cistern
cleaning and float-operated valve
maintenance/replacement
Screened vent
Large diameter header pipe
Gate valves
Large cold water cisterns interlinked in parallel

Cold water feed and distribution pipes

p Figure 5.51 Cisterns in parallel

Where it is not possible to connect cisterns in parallel, cisterns may be
connected in series.

Internal water flow Internal water flow
Secondary Primary
outlet outlet
p Figure 5.52 Cisterns in series

In practice, cisterns in series should be interconnected to allow free movement
of water from one cistern to the other. They should be connected at the bottom
and the middle so that water passes evenly through them. The primary outlet
connection should be made on the opposite cistern to the float-operated valve
to encourage water movement, with the secondary connection made on the
cistern with the float-operated valve installed. The overflow/warning pipe

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