Page 439 - 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

l the types and manufacturer of equipment and components installed
l the type of pressure test carried out and its duration
l the incoming static water pressure
● the flow rates and pressures at the outlets
l the expansion vessel pressure
l whether temperature and pressure relief valves have been fitted
● the results of tests on the discharge pipework.

The benchmark certificate should be signed by the operative and the customer,
and kept in a file in a secure location.

Hand over to the customer or end user
When the system has been tested and commissioned, it can then be handed
over to the customer. The customer will require all documentation regarding the
installation and this should be presented to them in a file, which should contain:
● all manufacturers’ installation, operation and servicing manuals for the
unvented hot water storage vessel and associated controls
● the commissioning records and certificates
l the Building Regulations Compliance certificate
● an ‘as fitted’ drawing showing the position of all isolation valves, backflow
prevention devices, etc.
The customer must be shown around the system and shown the operating
principles of any controls. Emergency isolation points on the system should be
pointed out and a demonstration given of the correct isolation procedure in the
event of an emergency. Explain to the customer how the systems work and ask
if they have any questions. Finally, highlight the need for regular servicing of
the appliances and leave emergency contact numbers.

6 DECOMMISSION SYSTEMS

AND COMPONENTS

Decommissioning hot water systems for maintenance and the replacement of
components can be a delicate task. It is important to ensure that the heat source
is totally isolated before work on the system begins. A notice should be placed
next to the heat source informing people that the system is decommissioned and
must not be turned on. Fuses to electric heaters, thermostats and motorised valves
should be removed and retained. If appliances are removed, any open pipes should
be capped off. The customer should be informed when the system is turned off.

The main components of hot water systems that require periodic maintenance
are as follows.

● The hot water storage vessel: should be periodically checked for any signs
of corrosion. Diminishing flow rates could indicate scale build-up in either
the cold feed connection or the hot water draw-off connection. These can
be removed and descaled as necessary. When replacing hot water cylinders,
the cylinder should be pre-assembled as much as possible before installation
begins, to reduce the time the hot water supply is off.

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