Page 342 - 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

the sound of running water remains, the communication pipe is leaking and
this must be repaired by the water undertaker. If the sound of running water
stops when the external stop valve is turned off, the leak is on the service pipe
to the property and this is the responsibility of the property owner.
● Leakage from the internal cold water system pipes and fittings: this
can cause a lot of damage to the property. It is fairly easy to detect the
source by isolating the mains cold water stop valve. If the water stops, it is
on the mains cold water supply. If the water continues to run, it is on the
distribution pipework. By isolating the mains internal stop valve and opening
the hot and cold water taps in the property, the system will drain quickly,
allowing repairs to be carried out.
● Leakage from taps and FOVs: dripping taps are an annoyance but they can
also waste quite a lot of water if they are dripping for a long time. If the
property is on a water meter, they can make a significant impact on the
water bill. Dripping FOVs are detected when the overflow to the cold water
storage cistern or the WC cistern begins to run. This can first show itself
by the overflow running only at night when the pressure of the water main
rises. Gradually, it will start to run all the time and will need to be repaired.

Commissioning cold water systems

Refer to Chapter 2, Common processes and techniques, for further information
on the commissioning of cold water systems.
● The commissioning and flushing procedure should be undertaken with fresh
wholesome water direct from the water undertaker’s main.
● Check that all pipework is secure and check that all tap connectors and tank
connectors are fully tightened, and all drain-off valves turned off.
● Check the inside of any cisterns installed to ensure that they are free of
debris and that all connections are tight.
● Ensure that all isolation valves and terminal fittings are off.
● Open the kitchen cold tap and slowly open the mains cold water stop valve.
Allow the water to flow into the kitchen sink to clear any debris that may
have collected in the pipework.
● Close the cold tap on the kitchen sink and allow the system to fill to full
standing pressure.
● Turn on the cold taps one at a time until the water runs clear, and check for leaks.
● Turn on the isolation valves to the float-operated valve in the WC cistern and
allow the cistern to fill to the water line. Adjust the water level as necessary.
Flush the WC and check for leaks.
● Fill any cisterns in the roof space and adjust the water level at the
float-operated valve as necessary.
● Open any taps and terminal fittings fed from the cistern and clear any air in
the system. Allow the water to run, to clear any debris.
● Allow the system to stand, then check for any leaks throughout the system.
● Isolate at the mains cold water stop valve and completely drain the system
to flush the system through. This should clear any flux residue and swarf
from the system.

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