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2.8.6 Combined pumped C.H. & Gravity D.H.W. systems
When this option of system is chosen:
The gravity hot water pipes to the indirect hot water cylinder
must be 28 mm diameter and be connected to each of the
28 mm connections on the flow and return manifold.
The pumped central heating pipes should be 22 mm diame-
ter and be connected to each of the 22 mm connections on
the flow and return manifolds. A gravity system requires a
minimum circulating head of 1 m assuming there is no hori-
zontal pipe run. If horizontal pipe runs are required then an
increase in head of 0,5 m is required for every additional 1 m
of horizontal pipe. Further details are available in the current
issues of BS5449 and BS6798.
7
TYPICAL SYSTEM DESIGN, FULLY PUMPED, OPEN VENTED.
Fig. 6
COMBINED PUMPED C.H. & GRAVITY D.H.W. SYSTEM
Fig. 7
