- 39 -
INST
ALLA
TION
- 39 -
INST
ALLA
TION
GENERAL REQUIREMENTS
turn valve, without the approval of the Local
Water Authority.
Mains water feed: hot water supply
The domestic section of the boiler is de-
signed to withstand an internal domestic
water pressure of 10 bar. Where it is likely
that the mains domestic water pressure may
exceed 5 bar, it is possible due to internal
“water hammer” effects that the pressure
within the domestic system can increase to
a level in excess of the 10 bar limit.
In these circumstances it is therefore rec-
ommended that a 3 bar pressure reducing
valve be fi tted to the incoming mains wa-
ter supply and a mini expansion vessel in-
stalled on the domestic circuit.
These devices will protect the boiler and the
domestic system from damage due to ex-
cessive domestic water pressure.
Filling
A method for initially fi lling the system and
replacing water lost during servicing must
be provided and it must comply with loca
water authority regulations.
The correct method is shown in Fig. 5.4 .
The temporary connection must be removed
immediately after fi lling.
Fig. 5.4
Temporary
connection
Control valve
Control valve
Double check valve
Supply pipe
(cold water inlet)
C.h. return pipe
The installer should ensure that no leaks ex-
ist either inside the boiler or on the system
as frequent fi lling of the system could cause
premature scaling of the heat exchanger.
Domestic water
5.9
The domestic water installation must be in
accordance with the relevant recommenda-
tions of BS 5546. Copper tubing to BS EN
1057 is recommended for water carrying
pipework and must be use for pipework car-
rying potable water.
For Ireland (IE), refer to I.S.813.2002.
Water treatment
5.10
C.h. circuit
Where a new boiler is fi tted to a new system
with either plastic or copper pipes, it is im-
portant the system is fully fl ushed, on com-
pletion, to ensure fl ux residues, swarfs, oils
and other installation debris is removed.
Where a new boiler is fi tted to an existing sys-
tem, it is important the debris from the existing
system is fully removed in order to ensure the
effi ciency of the new appliance is maintained.
Details on fl ushing procedure are given in
the section "Initial fi lling of the system" to
page 54 of this manual.
D.h.w. circuit (scale protection)
In areas where the water is ’hard’ (i.e. more
than 200 ppm total hardness as defi ned by
BS 7593: 1993 Table 2) it is recommended
that a proprietary scale-reducing device is
fi tted into the boiler cold supply, within the
requirements of the local water company.
Electrical supply
5.11
Warning, this appliance must be earthed.
External wiring to the appliance must be
carried out by a competent person and be in
accordance with the current I.E.E. Regula-
