Page 520 - 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

l On new-build installations, it is common practice to install microbore
pipework behind the dry lining plasterboard. In this instance, if the
pipework is made from copper, it should be clipped well and wrapped
to avoid noise and corrosion. Polybutylene pipe should be wrapped too,
but because the expansion of pipe on a hard surface could cause undue
abrasion on the soft plastic. A metallic tape should be placed at the back
of the polybutylene to allow the pipe to be found by metal-detecting tools
when it is covered.
l Pipes placed in chases should be wrapped against corrosion and insulated
where required.

General installation requirements are as follows:
l Feed and expansion cisterns must be fitted in accordance with the Water
KEY POINT Supply (Water Fittings) Regulations.
Cistern requirements are l Filling loops, expansion vessels and associated equipment should be
mentioned in Chapter 5, installed where they do not create an eyesore but are accessible. The
Cold water systems.
installation of expansion vessels should always be in accordance with
the manufacturer’s installation instructions. With system boilers and
combination boilers this does not present a problem as they are an integral
part of the appliance.
l Radiator position should be considered with care. It is generally accepted
that radiators be placed under windows, but this is not always the best
position if an even circulation of warm air is to be achieved. On new builds
and refurbishments, the radiator positions are usually marked on the detailed
building plans.
l Pipework must be insulated in places where there is a risk of freezing, such
as under a suspended timber floor and unheated garages. The Building
Regulations also advise that pipework in airing cupboards must be insulated
to prevent unwanted heat loss.
l All pipework and metal parts within the system must be electrically bonded
to earth.

KEY POINT Pressure testing and filling

l Before initial testing
takes place, the Testing
system should be The testing procedure is very similar to both hot and cold water installations,
visually checked to but the test pressure will depend on the type of system installed. As with other
make sure that it is
correct, that all visible systems, the test pressure is 1.5 times normal operating pressure and that
joints are tight and pressure will vary depending on the type of system installed. For instance:
that all clipping is l for sealed (pressurised) systems working at 1 bar pressure, the test pressure
in accordance with
the British Standard is 1.5 bar
distances. l for open vented systems, where the head of pressure is, say, 8 m then the
l Pipework testing is test pressure is 12 m, or 1.2 bar
covered extensively in l test timing should be in accordance with the Water Supply (Water Fittings)
Chapter 2, Common Regulations, BS 8558 and BS EN 806 and will depend on the material used
processes and in the installation.
techniques.
Testing should be conducted using a hydraulic test pump.
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