Page 18
Cold and Hot Water Distribution Network
a. As a minimum it is recommended that the cold supply to the appliance internally is
run in 22mm copper (or equivalent in plastic) and then from the appliance, hot and
cold services are in 22mm past the draw-off to the bath. For large properties bigger
sizes will be necessary and these should be proved by calculation in accordance
with BS6700. It is recommended that flow regulators are provided in the branch
to each terminal fitting (or in the fitting itself) to ensure best use is made of the
available pressure/flow.
b. The highest hot or cold water draw-off point should not exceed 4 metres above
the combination inlet valve fitted to the appliance.
c. In average size dwellings, the cold water supply to any mixer fittings (other than
dual outlet fittings) should be taken from the balanced cold outlet connection on
the combination valve fitted to the appliance. However, in larger dwellings with
a number of bathrooms and en-suites and/or long pipe runs, the balanced cold
supply must be provided with its own pressure regulating valve (set at the same
pressure as the one provided with the appliance ie 1.5 bar static) and not taken from
the appliance. When a separate pressure regulating valve is used for the balanced
cold water supply, it is recommended that a small expansion vessel (0.25 - 0.5 litre)
is fitted after the pressure regulator to accommodate the pressure rise caused by
the increase in temperature of the balanced cold water.
SH
WHB
SCV
SCV
WC BATH
22
22
15
15
WHB
WC
M
DC
DCV
DC
DCV
To
External
Tap
25mm MDPE
Incoming
Supply
WM or DWM
SINK
Discharge
Pipe
BoilerMate
HP-DEM
Ground
Level
mains c
old
hot
dischar
ge
balanc
ed c
old
Location
of optional
polyphosphate
scale inhbitor
- NOT REQUIRED
unless the hardness
level exceeds
300ppm (mg/l)
Typical cold and hot water network (to a smaller property)
Cold supplies to single taps taken from the mains cold water system.
Cold supplies to mixer taps only to be taken from the balanced cold water connection on the combination valve or in
larger property/minimum pressure situation from a separate pressure reducing valve.
Figure 1.11
d.
If the supply to the mixer fittings (other
than a dual outlet type) is not taken
from the balanced supply the system will
become over pressurized and cause the
pressure relief valve to discharge. Over
time this could also cause the premature
failure of the appliance itself which will
not be covered by the warranty.
e. Whenever possible the hot and cold water
supply to a shower-mixing valve should be
the first draw-off point on each circuit.
f. It is important that the mains cold water
pipe work is adequately separated from any
heating/hot water pipe work to ensure that
the water remains cold and of drinking water
quality.
DESIGN
SY
STEM DET
AILS
