Page 43
The pressure loss through a flow regulator at the
designated flow rate is about 1.8 bar. Therefore
for the flow regulator to control the flow rate at
pre-set level, the inlet pressure must be greater
than 1.8 bar. If the inlet pressure is lower, the
flow rate will be correspondingly less than the
pre-set values.
The maximum equivalent pipe lengths from
the manifold to the terminal fittings can be
estimated from the above information and
the resistance characteristics of the pipes.
The examples presented below are for 15mm
copper pipe in table 1 and for plastic pipework
in table 2.
The size of the distribution pipes supplying
the manifold should be calculated using
the method set out in BS 6700. A typical
diagrammatic arrangement of a system using
Manifold Type 1 is shown below.
This is only meant to show the principles
involved and the actual connection of fittings to
the manifold will need to suit the arrangements
shown on page 42.
Note: If it is proposed to fit chemical water
treatment such as a water softener this should
be fitted in this location and the cold water
branch in the sink should be branched off the
cold water main prior to the treatment device
instead of the cold water manifold.
Any other isolating/control valves and backflow
protection devices should be provided as
necessar y to comply with the Water
Regulations.
An optional location where
cupboard space is tight
Table 1: Maximum equivalent pipe length in 15mm copper
Inlet pressure
(bar)
Maximum equivalent length of pipe (m)
@ 9 l/m
@ 12 l/m
@ 18 l/m
2.0
25
10
5
2.5
75
30
15
3.0
150
60
30
Table 2: Maximum equivalent pipe length in plastic pipe
Inlet pressure
(bar)
Maximum equivalent length of pipe (m)
@ 9 l/m
@ 12 l/m
@ 18 l/m
2.0
1.5
15mm : 10
15mm : 4.5
22mm : 40
2.5
3.0
15mm : 20
15mm : 9.0
22mm : 80.0
3.0
4.5
15mm : 30
15mm 13.5
22mm : 120
APPENDIX
APPENDIX B
The preferred solution where
space will allow
Bath Toilet
cistern
Hand
basin
Toilet
cistern
Hand
basin
Hand
basin
Toilet
cistern
Mains
supply
Shower
DW
Kitchen sink
Kitchen
En-Suite
Bathroom
Check valve
NOT REQUIRED
unless chemical
water treatment
is fitted
Double check
valve NOT REQUIRED
unless supply pipe
services more than
one dwelling
Pressure limiting valve NOT REQUIRED
at pressures below 5 bar unless any
system components have a lower
maximum working pressure
Cloak room
WM
Thermal
Store
Scale
inhibitor
NOT REQUIRED
Airing
cupboard
See Note 1
