Technical data

Page 12
1.3 SYSTEM DETAILS
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 A-Class 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 A-Class at the
time of the maximum calculated simultaneous demand. If the manifolds (available as
an optional extra) are being used the inlet pressure to the manifold must be a minimum
of 2 bar. 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.
If you encounter a situation where the water pressure is adequate but fl ow rates are
poor please contact our technical helpline for details of an effective solution.
Note: Each BoilerMate A-Class is fi tted with a strainer and fl ow regulator on the cold
mains supply connection. If the supply pressure is less than 2 bar or if the manifolds
(available as an optional extra) are being used or if all taps are provided with fl ow
regulators the fl ow regulator on the cold inlet should be removed.
No check valve or similar device should be fi tted on the cold water supply branch to
the BoilerMate A-Class.
The Building Regulations L1A: New dwellings/L1B: Existing dwellings 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”.
1.0 DESIGN
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
plate heat exchanger is easily isolated and
quickly replaced with a service exchange unit
which can be obtained at a nominal cost from
Gledhill.
The hot water fl ow rate from the BoilerMate
A-Class 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.
Pressure limiting valve NOT
REQUIRED at pressures
below 5 bar unless any
components have a lower
maximum working pressure.
Second
dwelling
M.C.W.S
supply pipe.
Sink
Open vent
Cold feed/
expansion
Hand
basin
WC - fitted
with BS1212
ballvalve
Bath
BM A-Class
Optional
polyphosphate
scale inhibitor -
NOT REQUIRED
unless the hardness
level exceeds
300ppm (mg/l)
Shower.
H
aa
a
a
aa a
C
HC HC C
S.V.
Check valve NOT REQUIRED unless
chemical water treatment unit is fitted.
'a' - flow regulator recommended for better
balance of hot and cold water supplies.
Double check valve NOT REQUIRED unless supply
pipe services more than one dwelling.
Typical hot and cold water distribution
F&E Cistern