Page 464 - The City and Guilds Textbook: Plumbing Book 1 for the Level 3 Apprenticeship (9189), Level 2 Technical Certificate (8202) and Level 2 Diploma (6035)

The City & Guilds Textbook: Plumbing Book 1

Alternative central heating designs

Apart from the central heating systems we have already looked at, there are
two other pipework arrangements that can be installed in domestic premises.
These are:
1 the microbore system
2 the reversed return system.

The microbore system
The microbore system is a form of two-pipe system that uses a very small-bore
pipe to feed the heat emitters. The system uses a multi-connection fitting,
known as a manifold, fitted to the flow and return pipes and, depending on the
size of the system, these are either 22 mm or 28 mm in size. All of the flow
pipes to the heat emitters are taken from the flow manifold and all the returns
to the return manifold. The heat emitters are supplied through microbore
pipework, generally 8 mm or 10 mm in diameter. Manifolds are fitted in pairs
with the flow and return manifolds side by side.
In small dwellings all the radiators may be taken from one pair of manifolds,
which can accommodate up to eight radiators. It is usual, however, to fit a
separate pair of manifolds on each floor in a house and larger properties may
have two pairs on each floor. The pipework loops that serve the largest radiators
should be no more than 9 m in length.

Manifolds connected to 8 mm
or 10 mm microbore tubing
15 mm

22 mm

22 mm
22 mm

22 mm

p Figure 7.20 Microbore system

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