gledhill benchmark BMA 125 OV Design, Installation And Servicing Instructions Download

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Page 11

BOILERMA

A-CL

ASS

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 ﬁtted 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 ﬂow rates are
poor please contact our technical helpline for details of an effective solution.

Note

: Each BoilerMate A-Class is ﬁtted with a strainer and ﬂow 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 ﬂow
regulators the ﬂow regulator on the cold inlet should be removed.

No check valve or similar device should be ﬁtted on the cold water supply branch to
the BoilerMate A-Class.

To comply with the Benchmark Guidance Note for Water Treatment in Heating and
Hot Water Systems the installer should check the hardness level of the water supply
and if necessary ﬁt an in-line scale inhibitor/reducer to provide protection to the
whole of the domestic water system. See Appendix C for a copy of the relevant part
of the Benchmark Guidance Note.

1.0 DESIGN

The standard appliance is suitable for hardness
levels up to 280 ppm without the use of a scale
inhibitor. For hardness levels above 280ppm
(mg/l) we would recommend that the appliance
is ordered with the optional factory ﬁtted scale
inhibitor.

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  ﬂow  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 deﬁned
in BS 6700.

If  a  water  meter  is  ﬁtted  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.

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