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DESIGN
SY
STEM
DE
TAILS
Hot and Cold Water System
Pipe Sizing / Materials
To achieve even distribution of the available supply of hot and cold water, it is
important in any mains pressure system, that the piping in a dwelling should be sized
in accordance with BS 6700. This is particularly important in a large property with
more than one bathroom.
However, the following rule of thumb guide lines should be adequate for most smaller
property types as long as water pressures are within the recommended range of 2-3
bar.
1. A 15mm copper or equivalent external service may be sufficient for a small
1bathroom dwelling (depending upon the flow rate available), but the minimum
recommended size for new dwellings is 22mm (25mm MDPE). For the BMA 225
model we recommend a 28mm (32mm MDPE) supply pipe.
2. The internal cold feed from the main incoming stop tap to the BoilerMate should
be run in 22mm pipe. The cold main and hot draw-off should also be run in 22mm
as far as the branch to the bath tap.
3. The final branches to the hand basins and sinks should be in 10mm and to the
baths and showers in 15mm. (1 metre minimum)
4. If an external hose tap is provided this should be branched in 15mm pipework
from the cold pipework as near to the incoming mains as possible.
5.
We would recommend that best results for a balanced system are
achieved by fitting appropriate flow regulators to each hot and cold
outlet. This is particularly relevant where the water pressures are above the
recommended water pressure range of 2-3 bar, or the dwelling is 3 storey.
Details of suitable flow regulators are provided in Appendix.
Note: If manifolds are being used suitable flow regulators need to be provided
at each outlet.
All the recommendations with regard to pipework systems in this manual are generally
based on the use of BS/EN Standard copper pipework and fittings.
However, we are happy that plastic pipework systems can be used in place of copper
internally as long as the chosen system is recommended for use on domestic hot
and cold water systems by the manufacturer and is installed fully in accordance with
their recommendations.
It is also essential that if an alternative pipework material/system is chosen the
manufacturer confirms that the design criteria of the new system is at least equivalent
to the use of BS/EN Standard copper pipework and fittings.
Taps/Shower Fittings
Aerated taps are recommended to prevent splashing.
Any type of shower mixing valve can be used as long as both the hot and cold
supplies are mains fed. However, all mains pressure systems are subject to
dynamic changes particularly when other hot and cold taps/showers are opened
and closed, which will cause changes in the water temperature at mixed water
outlets such as showers. For this reason and because these are now no more
expensive than a manual shower we strongly recommend the use of thermostatic
showers with this appliance. These must be used in 3 storey properties where
the impact on pressure/temperature of opening another tap in the system is
greater than normal.
The shower head provided must also be suitable for mains pressure supplies.
However, if it is proposed to use a ‘whole body’
or similar shower with a number of high flow/
pressure outlets please discuss with the Gledhill
technical department.
The hot water supply to a shower-mixing valve
should be fed wherever practical directly from
the BoilerMate A-Class or be the first draw-
off point on the hot circuit. The cold supply
to a shower-mixing valve should wherever
practical be fed directly from the rising mains
via an independent branch. The shower must
incorporate or be fitted with the necessary
check valves to provide back-syphonage
protection in accordance with the Water
Regulations.
The supply of hot and cold mains water directly
to a bidet is permitted provided that it is of the
over-rim flushing type and that a type ‘A’ air gap
is incorporated.
Hot and Cold Water System.
If the length of the hot water draw off
pipework is excessive the delivery time may
be unacceptable before hot water is available
at the tap, you may wish to consider using trace
heating to the hot water pipework such as the
Raychem HWAT system. Please consult Gledhill
Technical Department for further details.
It is important that the cold water pipework
is adequately separated/protected from any
heating/hot water pipework to ensure that
the water remains cold and of drinking water
quality.
Summary of Contents for BMAS 150 OVR
Page 38: ...Page 38 APPENDIX APPENDIX B ...
Page 40: ...Page 40 APPENDIX D NOTES ...
Page 41: ...Page 41 NOTES ...
