Siting The Appliance - Worcester benchmark ZWB 7-25 R 25 HE Design, Installation And Servicing Instructions

The water capacity of the system is shown in table 12,
page 27. If a greater capacity is required then an addi-
tional expansion vessel must be fitted into the system
Domestic
hot water
Fig. 6 Sealed primary water system
If the system pressure is greater than 2.65 bar when the
appliance is operating at maximum temperature then an
additional expansion vessel must be fitted into the sys-
tem return as close to the appliance as possible.
The filling point must be at low level and arranged as
shown in figs. 6 and 5.
The pressure relief valve is set to operate at 3 bar.
There must be no connection to the mains without the
approval of the local water company. All connections in
the system must be capable of withstanding a pressure
of up to 3 bar and the radiator valves conform to the
requirements of BS 2767:10.
Fit Thermostatic Radiator Valves to radiators in the
sleeping accommodation and not to the radiator where
the room thermostat is sited, this must be left open.
Repeated venting probably indicates a leak and this
must be rectified to ensure the proper operation of the
appliance.
No galvanised radiators or pipes must be used.
If any system water treatment is required then
use only products suitable for use with Alumin-
ium shall be used i.e Fernox- Copal or Supercon-
centrate or Sentinal X100, in accordance with the
manufacturers instructions. The use of any other
substances will invalidate the guarantee. The pH
value of the system water must be less than 8 or
the appliance guarantee will be invalidated.
Suitable products are available from Betz-Dearborn
Tel.: 0151 4209563 and Fernox Tel.: 01799 550811
A drain cock to BS2879 must be fitted to the lowest
point of the system.
IMPORTANT: Check that no dirt is left in the
water pipework as this could damage the appli-
ance. Thoroughly flush the heating system and
6 720 611 441 GB (03.11)
APPLIANCE
Refer to
Appliance
Water Flow
Diagram
WRC
approved
filling loop
Central heating return
Central heating flow
BS stop valve
Fixed spindle type.
Water main
return as close to the appliance as possible. The system
pressure can be set up to a maximum of 1.5 bar with 1
bar being the normal setting.
Radiator valve Lockshield valve
A drain cock should be fitted at the lowest point of the
heating circuit and the appliance
the mains water supply before fitting the appli-
ance to the wall in accordance with the recom-
mendations of BS7593:1992.
3.4

Siting the appliance

Regulations concerning the Installation Site
B Relevant national regulations must be complied with
section 3.9.1.
B Consult the installation instructions for details of min-
imum clearances required.
Combustion air
In order to prevent corrosion, the combustion air must
not contain any corrosive substances.
Substances classed as corrosion-promoting include
halogenated hydrocarbons which contain chlorine and
fluorine compounds and are contained in some sol-
vents, paints, adhesives, aerosol propellants and house-
hold cleaners, for example.
Surface temperature
The max. surface temperature of the casing and the flue
is less than 85 °C.
This means that, no special safety precautions are
required with regard to flammable building materials
and fitted furniture. The specified clearances must be
maintained.
Cupboard/Compartment
The appliance can be installed in a cupboard/compart-
ment need for airing clothes providing that the require-
ments of BS6798 and BS5440:2 are followed. The low
casing losses from the appliance eliminate the need for
ventilation openings in the compartment.
Installation
6 720 610 576 -09.3O
13