Page 413 - 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 6 Hot water systems

Pressure relief value
Pressure reducing value

Reduced pressure cold water Cold water inlet
outlet to the hot water storage
vessel

Strainer Single check value

Balanced cold connection
p Figure 6.47 A typical composite valve

Some composite valves may also contain an isolation valve. With all controls
contained in a single valve, making the connection to an unvented hot water
storage vessel is a simple matter of just connecting the cold supply, without
the need to ensure that the controls have been fitted in the correct order.

Isolation valve
Composite valve
Expansion vessel Balanced cold water

p Figure 6.48 Position of a composite valve

Unvented hot water systems: the discharge pipework

The layout features for temperature and expansion relief
(discharge) pipework
With unvented hot water systems, there is always the possibility, however
undesirable, that the pressure relief and temperature relief valves may discharge
water. The discharge pipework is designed specifically to remove the discharged
water away from the building safely. It is, therefore, very important that it is
installed correctly with the correct size of pipe and that the pipework is made
from the correct material, especially since the water discharged may be at near
boiling point.

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