gledhill BMBP125, Design, Installation & Servicing Instructions

Page: 10 / 28

Page 10
DESIGN
SY
STEM DET
AILS
Hot and Cold Water System
General
A schematic layout of the hot and cold water services in a typical small dwelling is
shown below. BoilerMate BP will operate at mains pressures as low as 1 bar and as
high as 5 bar although the recommended range is 2-3 bar. These pressures are the
minimum dynamic pressures at the cold connection to the BoilerMate BP at the time
of the maximum calculated simultaneous demand. Particular consideration should also
be given to available pressures in the case of 3 storey properties. It is also important
to check that all other equipment and components in the hot and cold water system
are capable of accepting the mains pressure available to the property. If the mains
pressure can rise above 5 bar or the maximum working pressure of any item of
equipment or component to be fi tted in the system a pressure limiting (reducing)
valve set to 3 bar will be required.
No check valve or similar device should be fi tted on the cold water supply branch to
the BoilerMate BP.
The Building Regulations L1A, L1B and the requirements set out in the Domestic
Heating Compliance Guide specify that “where the mains water hardness exceeds
200ppm provision should be made to treat the feed water to water heaters and the
hot water circuit of combination boilers to reduce the rate of accumulation of lime
scale”.
To comply with this requirement the hardness of the mains water should be checked by
the installer and if necessary the optional factory fi tted in-line scale inhibitor should be
specifi ed at the time of order for hardness levels between 200 and 300 ppm (mg/l).
Where the water is very hard ie 300ppm (mg/l) and above the optional polyphosphate
type, inhibitor should be specifi ed at the time of order. However, this will need to be
fi tted by the installer at a suitable point in the
cold water supply to the appliance.
If scale should ever become a problem the
BoilerMate BP heat exchanger can be descaled
in situe. Contact the Technical Helpline for more
details.
The hot water fl ow rate from the BoilerMate
BP is directly related to the adequacy of the
cold water supply to the dwelling. This must
be capable of providing for those services,
which could be required to be supplied
simultaneously, and this maximum demand
should be calculated using procedures defi ned
in BS 6700.
If a water meter is fi tted in the service pipe,
it should have a nominal rating to match the
maximum hot and cold water peak demands
calculated in accordance with BS 6700. This
could be up to 80ltr/min in some properties.
Warning/
overflow
pipe
MCWS
Safety/open vent
Shower
Expansion/
cold feed
Second
dwelling
Pressure limiting valve
NOT REQUIRED at
pressures below 5 bar
unless any components
have a lower
maximum working
pressure
Double check valve
NOT REQUIRED unless
pipe supplies more
than one dwelling
‘a’ - flow regulator recommended for
better balance of hot and cold
water supplies
MCWS
supply
pipe
Sink
H C
a a
SV
a a a a
Bath
H C
Hand basin
H C
WC - fitted
with BS1212
ballvalve
C
Figure 8
Typical hot and cold water distribution
BOILERMATE BP
Check valve
NOT REQUIRED unless
chemical water
treatment unit is fitted
a
Top up cistern