Page 517 - 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 7 Central heating systems

Solid fuel

Solid fuel is still used in rural areas of the UK where access to piped fuel supply
is difficult. Solid fuel is available in many different forms, including:
l coal
l coke
l anthracite
l biomass wood pellets (carbon neutral).

Warm air systems
Warm air systems are not often fitted in modern domestic properties in the UK,
although they remain popular in parts of the USA. They work by blowing warm
air through duct work into the rooms of the property via grilles, which can be
located high on the wall or in the floor. The air is heated usually by a gas boiler
and the heated air is distributed by an electric fan. Some boilers also contain a
small water heat exchanger to heat the hot water for the property.

Electric storage heaters

Electric storage heaters were very popular in the 1980s and 1990s. They contain
a series of ceramic bricks, which are heated by electric elements overnight using
cheap rate electricity. The bricks store the heat and release it slowly during the
day.

The heaters have two settings that can be operated either automatically or
manually:

1 Charge – this controls the amount of heat that is stored
2 Draught – this controls the rate at which the heat is released.

They also have a day ‘top-up’ should the heaters require to be reheated for
short periods during the day.
This type of heater is expensive to install and run. Because of this, their use
today is very limited.

District heating

District heating utilises a very large central heat generating plant to heat
hundreds of homes from the same system. They are very popular in Europe and
some parts of the USA.

Pipes laid beneath the street distribute hot water (sometimes steam) from the
central generating plant to a local substation. From here the heat is controlled
to around 120°C, where it is delivered to all properties via a heating interface.
The heating interface replaces the properties boiler as the heat source. From
here, normal heating systems such as the S-plan and S-plan plus can be installed
and controlled in the normal way.
District heating systems are often installed as part of a combined heat and
power system, as discussed in Chapter 10, Domestic fuel systems.

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