Page 333 - 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 5 Cold water systems

The installation of showers and shower pumps will be covered in more detail in
Chapter 6, Hot water systems.

Scale reduction and water treatment

in domestic properties
As well as the treatment given to the water by the water undertaker, many INDUSTRY TIP
domestic properties, especially in hard water areas, employ alternative methods
to condition the water so that scaling problems do not occur. Remember: it is not permitted
to fit shower pumps on mains
Scaling occurs in hot and cold water systems and central heating installations cold water installations. The
when the water contains salts and minerals, such as calcium carbonate, that Water Supply (Water Fittings)
re-forms in the water as a hard limescale that sticks to the inside of pipes and Regulations prohibit the
appliances. This process is known as precipitation. The resulting limescale reduces use of pumps on mains cold
the appliance’s efficiency and can, in some cases, make the appliance unusable. water except when special
permission has been given
There are several methods we can use to prevent precipitation from occurring;
these include the use of: by the water undertaker.
● water conditioners
● water softeners
● water filters.
In this part of the chapter, we will look at the use of these appliances and how
they work.

Water conditioners p Figure 5.111 Magnetic scale
inhibitor
The term ‘water softener’ is used to describe a variety of products that are
designed to prevent the build-up of limescale. Water conditioners (also known
as limescale inhibitors) work by altering the chemistry of the precipitation
process by suppressing limescale formation and thereby reducing the rate of
scaling. There are many different types of water conditioner using a wide variety
of conditioning methods, including those described below.
● Magnetic: prevents scale build-up by influencing the type of calcium
crystals precipitated, which ensures that only needle-like aragonite crystals p Figure 5.112 Electrolytic scale
inhibitor
are formed. These find it harder to stick to smooth surfaces than the normal
calcium crystals. These are for individual appliance
protection only, such as combi boilers. They are installed
Rising main
on the cold main to the appliance.
● Electrolytic: these work by adding a minute amount Electrolytic water
conditioner
of zinc to the water, which suppresses the formation of
calcium crystals. Any crystals that are formed are washed
away by the flow of water. Can be used for whole-house
protection.

Stop valve

p Figure 5.113 Fitting an electrolytic water conditioner

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