Page 367 - 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

installations, are governed much more rigidly because of the safety features
that must be installed. Other systems, such as vented hot water installations,
do not require such tight regulation but may not meet the specification of the
appliances fitted.
Whichever system is fitted, the regulations that cover its installation must be
adhered to at all times.

Choosing the right hot water system

When the above points are considered, the choice of hot water system should
be quite a straightforward affair. Certain dwellings almost dictate the system
that should be fitted. For example, it would be foolhardy to install a combi
boiler in a dwelling with three bathrooms, a kitchen, utility room and downstairs
washroom. The hot water demand would be more than the boiler could cope
with. By far the main considerations that must be taken into account are the
type and number of appliances, and their pattern and frequency of use. Knowing
this will indicate the correct choice of system to install and the customer can
then be advised accordingly.
Hot water
supply

Localised or
Centralised system single point system

Instantaneous Storage Instantaneous Storage

Open
Thermal Combination vented/cistern Gas storage Unvented Gas fired Open vented
store vented 'Fortic' water system mains hot water
systems fed system fed system heater
Combi boiler or Unvented
instantaneous Direct Indirect Direct Indirect Indirect Electric hot water
water heater heater
Combined Small hot Small hot
primary water only water only Direct
storage units boiler boiler
Immersion Immersion
heater heater
p Figure 6.1 Types of hot water system
2 HOT WATER SYSTEMS

AND COMPONENTS

Identify types and layout features of hot

water systems

In this section, you will compare the types of hot water supply systems used in
dwellings and describe their applicable pipework layout features.
Hot water systems include:
● centralised systems – unvented hot water systems and vented hot water
systems
● localised systems – unvented point-of-use heaters and instantaneous heaters

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