Page 528 - 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

Decommissioning central heating systems

When decommissioning central heating systems, there are a number of
procedures to be observed:
l Isolation of services: ensure that all relevant services, such as gas, water and
electricity, are isolated before commencing the decommissioning process.
If possible, localised isolation, such as removing fuses or isolating water at
isolation valves, etc., is preferable so that the customer is not left without
services for too long. You must seek the customer’s permission before
isolating any services.
l Warning notices and signs: warning signs saying that the system is isolated
and must not be reinstated should be placed at the point of isolation, so
that other users/customers know that the system is being worked on. If the
isolation point is a long distance from your point of work, leave a contact or
mobile number so that the customer can contact you with any queries.
l Temporary continuity bonding: temporary continuity bonding must be
carried out when removing electrical components, such as circulating pumps
and motorised valves. Temporary continuity bonding is absolutely essential
when making new connections involves cutting into existing pipework. It is
here that the risk from electrocution is at its greatest, as earth leakage faults
on electrical systems are not always noticeable.
l Drainage and disposal of systems’ contents and components: the
water from central heating systems often contains chemicals that are
very mildly toxic, such as inhibitors, scale preventers and sludge removers.
These must be disposed of carefully down a foul water sewer and not a top
water or rainwater drain. Top water drains often dispose of water straight
into a watercourse, river or stream, and the chemicals may be harmful to
aquatic life.
l Capping of pipework: no matter for how long the system is to be
decommissioned, the capping of pipework is essential in case of the system
being accidentally turned on. In the case of gas systems, the cap should be
installed and the system fully tested according to the Gas Safety (Installation
and Use) Regulations 1998 to ensure that, should the system be accidentally
turned on, it is completely gas tight and safe.

SUMMARY

This has been the most challenging chapter in the book for us so far. The
myriad of systems, layouts, appliances, components and fuels are confusing,
but each one has its tell-tale signs that make it unique. The art to good system
recognition is looking – just as the key to good system fault diagnosis is
listening. This chapter gives us the foundation to do both.
A good central heating system is one that is efficient in use, warms the home
to the right temperature, is quiet in operation and is installed to the highest
possible standards. This can be achieved only with the knowledge that allows us
to recognise the possibilities of efficiency, design with the customer in mind and
installation to the best of our ability.

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