Page 378 - 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

Factory-fitted internal vent

Hot water draw-off

Primary flow connection
1" male thread

Factory-fitted cold
feed connection

Primary return connection
1" male thread
p Figure 6.11 Combination open
vented hot water storage
cylinder p Figure 6.10 The layout of a combination open vented hot water storage cylinder

Integrating a cold water feed cistern and a hot water cylinder in a compact
all-copper unit is an effective way of providing adequate supplies of hot water
when storage space is limited. It also enables a dry roof space, eliminating the
risk of freezing. It is an ideal system for rented accommodation due to its low
maintenance requirement.
The main problem with this type of cylinder is the lack of water pressure at the
taps. The cold water storage is very close to the hot water cylinder and so the
static head of pressure is very low. Because of this, Fortics need to be installed as
high as possible (but not in the roof space) to improve the pressure at the outlets.

Power shower pumps may also cause a problem because the cold water storage
cistern cannot replenish itself quickly enough to feed the shower pump. The
cistern is not designed to supply hot and cold water systems, and so shower
pumps must not be fitted to this type of hot water supply.

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