Page 337 - 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

Cold water pipes should not be installed in the same notch as hot water and
central heating pipes. There must be a minimum horizontal distance of
300 mm between cold water pipes and any hot water/central heating pipes to
prevent radiated heat from warming the cold drinking water. Where there is a
significant risk of cold water pipes being warmed by other pipework, the cold
water installation should be lagged. To eliminate the risk of contamination from
undue warming, the cold water pipework must never be allowed to exceed a
temperature of 25°C.

Pipes in walls and sleeved through walls

According to Defra’s guidance on the Water Supply (Water Fittings)
Regulations 1999:
Unless they are located in an internal wall which is not a solid wall, a chase or
duct which may readily be removed or exposed, or under a suspended floor
which may be readily removed and replaced, or to which there is access, water
fittings shall not be:
1 Located in the cavity of a cavity wall, or;
2 Embedded in any wall or solid floor, or;
3 Installed below a suspended or solid floor at ground level.
Where the laying of pipes in walls and floors is unavoidable, they should
be placed in purpose-made ducts that have an accessible, removable cover,
as shown in Figure 5.118. Pipes laid in chases must have adequate room for
expansion and contraction, and should be sufficiently lagged or protected.

Floor screed Insulated pipe in duct

Access cover
Insulated pipe in duct

Plasterboard

Pipe clipped to joist Insulation
Access cover
Insulated pipe
in duct

Plasterboard

p Figure 5.118 Pipe in walls and floors

Pipes passing through walls should be sleeved to allow for expansion and to
protect the pipe from building settlement and the corrosive effects of the
masonry on the pipe. The sleeve should be sealed at both ends. The pipe
should be thermally insulated where necessary.

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