Page 366 - 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

exceed the maximum distances for hot water dead legs, which excludes some
hot water systems. In these cases, only systems that can incorporate secondary
circulation should be considered.

Running costs and energy efficiency

New, more efficient methods of heating water are constantly being developed.
Perhaps the most important recent development is that of solar hot water
heating, which can, theoretically, offer a 60 per cent saving on domestic hot
water heating costs, despite its initial costly installation. The development of
fuel-efficient condensing oil and gas boilers and storage cylinders with fast heat
recovery times have also helped in terms of energy efficiency.

Environmental impact: the type(s) of fuel to be used

With most storage hot water systems, multiple fuels may be used in one system,
i.e. utilising gas, oil or solid fuel as the main fuel source, with an electrical
alternative (immersion heater) as back-up or for summer use. Multipoint
heaters do not have this capability and so fuel type usage is very limited. The
environmental impact of fuels like gas and oil are now important considerations,
especially in buildings where a low/zero carbon footprint is preferred.

Appliance location: the number of hot water outlets
Again, an important point because this may automatically exclude such
appliances as combi boilers and instantaneous heaters because, although classed
as multipoint heaters, only one outlet at a time may be opened satisfactorily,
whereas other types of hot water system may allow multiple open taps with
a good flow rate. This becomes important where there are long distances
between the appliance and the hot water source.

Installation and maintenance costs
This is also a very important point because of the size of the system, and initial
cost of the appliance and materials. Add to this the installation costs and any
maintenance costs over the lifetime of the system.

Storage type/location

The type of hot water storage system used (vented or unvented) will play a vital
part in its location within the dwelling. While a vented system may be fitted in
an airing cupboard, an unvented system generally requires much more space
than that available in an airing cupboard, because of the need for safety and
functional controls. The distance from the outlets also may create a problem
because the longer the run of hot water pipework, the greater the need for
secondary circulation. Location of the storage vessel is, therefore, of great
importance.

Legislation
As with all plumbing systems, the legislation that covers the installation of hot
water systems must be considered. Some systems, such as unvented hot water

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