gledhill BM125 Installation And Servicing Instructions page 11

1.3 SYSTEM DETAILS
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).
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 fi nal branches to the hand basins and sinks should be in 10mm and to
the baths and showers in 15mm. (1 metre minimum)
4. We would recommend that best results for a balanced system are achieved
by fi tting appropriate fl ow 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. Details of suitable fl ow regulators are
provided in Appendix A.
Note: If manifolds (available as an optional extra) are being used suitable fl ow
regulators are automatically provided in the manifold and do not need to be
provided at each outlet - See Appendix B for further details.
All the recommendations with regard to pipework systems in this manual are
generally based on the use of BS/EN Standard copper pipework and fi ttings.
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.
This is particularly important in relation to use of push fi t connections when using
the optional fl exible hose kits - see 2.2 Installation, Pipework connections.
It is also essential that if an alternative pipework material/system is chosen the
manufacturer confi rms that the design criteria of the new system is at least equivalent
to the use of BS/EN Standard copper pipework and fi ttings.
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.
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 fl ow/pressure outlets please discuss with the Gledhill technical department.
1.0 DESIGN
The hot water supply to a shower-mixing valve
should be fed wherever practical directly from
the BoilerMate 2000 or be the fi rst 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 fl ushing 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 and the delivery time will be more
than 60 seconds 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.
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