Page 465 - The City and Guilds Textbook: Plumbing Book 1 for the Level 3 Apprenticeship (9189), Level 2 Technical Certificate (8202) and Level 2 Diploma (6035)
P. 465
Chapter 7 Central heating systems
Table 7.5 Advantages and disadvantages of the microbore system
Advantages Disadvantages
Contains only a small amount of water and Microbore piping is easily damaged and not
so is heated quickly very resistant to knocks
Microbore tubing comes in fully annealed Microbore tubes can easily get blocked with
coils, is easily bent by hand and is easily sludge if the system is installed poorly
hidden
It can sometimes be a cheaper form of
installation
Long lengths of tubing mean fewer joints
Can be used with sealed and open vented
systems, Y-plan or S-plan
The system is Building Regulations
Document L compliant
The reversed return system
The reversed return system is designed for larger systems and is a variation on
the two-pipe system. In the reversed return system, the flow and returns are p Figure 7.21 Microbore manifolds
connected, as before, to separate flow and return pipes, but the return travels
away from the boiler in the same direction as the flow before looping around to
be connected to the return at the boiler. By doing this, the amount of pipe used
on both flow and the return is almost equal, which has the effect of ensuring
that all of the heat emitters reach full temperature at about the same time.
Reversing the return makes balancing the system much quicker and easier and,
in some cases, balancing is eliminated completely.
22 mm
15 mm
15 mm
22 mm
22 mm
15 mm
15 mm
22 mm
p Figure 7.22 The reversed return system
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