Page 365 - 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

pumps, solar thermal panels and micro-combined heat and power systems
are also discussed. The guide also refers to other publications that refer to
techniques to assist in the design and installation of systems that are over
and above the standard that is required by the Building Regulations.

Manufacturer technical installation and
maintenance instructions

Unvented hot water storage systems must be fitted, commissioned and
maintained strictly in accordance with the manufacturer’s instructions. These
contain vital information for the correct and safe installation, operation and
maintenance of the system and its components, such as:

● the minimum required pressure and flow rate of the incoming supply,
for satisfactory operation of the system INDUSTRY TIP
● the minimum size of the incoming cold water supply
● the minimum size of any hot water distribution pipework If the manufacturer’s
● the required heat input and heat recovery time instructions are not available
● any electrical installation requirements or have been misplaced, most
manufacturers now offer
● the operation of any controls the facility to download the
● the calculation required to ascertain the correct size of the discharge pipework instructions from their website.
● fault-finding techniques.

Factors affecting hot water systems

You will learn about the factors that affect the selection of hot water systems
for dwellings, with consideration of:
● customer needs/occupancy and purpose ● appliance location
● building layout and features ● cost
● energy efficiency ● storage type/location
● environmental impact ● legislation.

The type of system we choose will depend on the following points.
The customer’s needs/occupancy and purpose

This concerns the number of occupants and the amount of hot water required.
Larger households will require more hot water, which can be supplied in a
number of ways, i.e. an instantaneous water heater giving unlimited hot water
amounts or a large hot water storage cylinder, although other factors must also
be considered before a decision is made.

Building layout and features: the size of the property
and the distance from the outlets

The Water Supply (Water Fittings) Regulations stipulate the maximum distance
that a hot water supply pipe may run without constituting wastage of water.
This is because of the amount of cold water that is drawn off before hot water
arrives at the taps. This ‘dead’ cold water must be limited. Large properties may

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