Page 433 - 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

3 the Building Regulations Approved Document G3
4 the manufacturer’s instructions of any equipment and appliances.

The documents required for correct testing and commissioning were
investigated in Chapter 5, Cold water systems.

The checks to be carried out during a visual inspection of an
unvented hot water storage system to confirm that it is ready to
be filled with water
Before soundness testing a hot water system, visual inspections of the
installation should take place. These should include:
● walking around the installation; check that you are happy that the
installation is correct and meets installations standards
● check that all open ends are capped off and all valves isolated
l check that all capillary joints are soldered and that all compression joints
are fully tightened
l check that sufficient pipe clips, supports and brackets are installed, and that
all pipework is secure
l check that the equipment, i.e. unvented hot water storage cylinder, shower
boosting pumps, expansion vessels and subsequent safety and functional
controls, are installed correctly and that all joints and unions on and around
the equipment are tight
l check that the pre-charge pressure in the expansion vessel is correct and in
accordance with the manufacturer’s data
l check that any cisterns installed on open vented hot water storage systems
are supported correctly and that float-operated valves are provisionally set
to the correct water level
l check that all appliances’ isolation valves and taps are off; these can be
turned on and tested when the system is filled with water
● check that the D1 and D2 discharge pipework complies with the Building
Regulations and that it terminates in a safe but visible position.

The initial system fill
The initial system fill is always conducted at the normal operating pressure of the
system. The system must be filled with fluid category 1 water direct from the water
undertaker’s mains cold water supply. It is usual to conduct the fill in stages so that
the filling process can be managed comfortably. There are several reasons for this:
● Filling the system in a series of stages allows the operatives time to check for
leaks stage by stage. Only when the stage being filled is leak free should the
next stage be filled.
● Open vented systems: air locks from cistern-fed open vented systems
are less likely to occur, as each stage is filled slowly and methodically. Any
problems can be assessed and rectified as the filling progresses without the
need to isolate the whole system and initiate a full drain down. Allowing
cisterns to fill to capacity and then opening any gate valves is the best way
to avoid air locks. This ensures that the full pressure of the water is available

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