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If the gas supply serves more than one appliance, it must be
ensured that an adequate supply is maintained to each appli-
ance when they are in use at the same time.
NOTE
It is recognised that 'pressure loss' through the gas cock and
gas valve may result in a pressure drop of approximately 2mbar
between the gas meter and gas valve inlet test point; this will
not impair the performance of the appliance, provided that a
dynamic pressure of 18mbar is available at the appliance inlet.
3A.4 FLUE SYSTEM
The terminal should be located where the dispersal of combustion
products is not impeded and with due regard for the damage
and discoloration that may occur to building products located
nearby. The terminal must not be located in a place where it is
likely to cause a nuisance (see I.S. 813).
In cold and/or humid weather, water vapour will condense
on leaving the terminal; the effect of such pluming must be
considered.
If installed less than 2m above a pavement or platform to
which people have access (including balconies or flat roofs)
the terminal must be protected by a guard of durable material.
The guard must be fitted centrally over the terminal. Refer to
I.S. 813, when the terminal is 0.5 metres (or less) below plastic
guttering or 1 metre (or less) below painted eaves.
3A.5 AIR SUPPLY
The following notes are intended for general guidance only.
This appliance is a room-sealed, fan-flued boiler, consequently it
does not require a permanent air vent for combustion air supply.
When installed in a cupboard or compartment, ventilation for
cooling purposes is also not required.
3A.6 WATER CIRCULATION
Specific recommendations are given in I.S. 813. The following
notes are for general guidance only.
3A.6.1 PIPEWORK
It is recommended that copper tubing be used in conjunction
with soldered capillary joints.
Where possible pipes should have a gradient to ensure air
is carried naturally to air release points and that water flows
naturally to drain cocks.
Except where providing useful heat, pipes should be insulated
to avoid heat loss and in particular to avoid the possibility of
freezing. Particular attention should be paid to pipes passing
through ventilated areas such as under floors, loft space and
void areas.
3A.6.2 AUTOMATIC BY-PASS
The appliance has a built-in automatic by-pass, consequently
there is no requirement for an external by-pass, however the
design of the system should be such that it prevents boiler
'cycling'.
3A.6.3 DRAIN COCKS
These must be located in accessible positions to facilitate
draining of the appliance and all water pipes connected to the
appliance.
3A.6.4 AIR RELEASE POINTS
These must be positioned at the highest points in the system
where air is likely to be trapped. They should be used to expel
trapped air and allow complete filling of the system.
3A.6.5 EXPANSION VESSEL
The appliance has an integral expansion vessel to accom-
modate the increased volume of water when the system is
heated. It can accept up to 8 litres of expansion from within
the system, generally this is sufficient, however if the system
has an unusually high water content, it may be necessary to
provide additional expansion capacity (see 6.18).
3A.6.6 FILLING POINT
A method for initial filling of the system and replacing water
lost during servicing etc. must be provided (see fig. 8). You
should ensure this method of filling complies with the local
water authority regulations.
3A.6.7 LOW PRESSURE SEALED SYSTEM
An alternative method of filling the system would be from an
independent make-up vessel or tank mounted in a position
at least 1 metre above the highest point in the system and at
least 5 metres above the boiler (see fig. 9). The cold feed from
the make-up vessel or tank must be fitted with an approved
non-return valve and stopcock for isolation purposes. The feed
pipe should be connected to the return pipe as close to the
boiler as possible.
3A.6.8 FREQUENT FILLING
Frequent filling or venting of the system may be indicative
of a leak. Care should be taken during the installation of the
appliance to ensure all aspects of the system are capable of
withstanding pressures up to at least 3 bar.
3A.7 ELECTRICAL SUPPLY
The appliance is supplied for operation on 230V @ 50Hz
electrical supply; it must be protected with a 3-amp fuse. The
method of connection to the mains electricity supply must allow
for complete isolation from the supply. The preferred method is
by using a double-pole switch with a contact separation of at
least 3,5 mm (3° high-voltage category). The switch must only
supply the appliance and its corresponding controls, i.e. time
clock, room thermostat, etc.
3A.8 MOUNTING ON A COMBUSTIBLE SURFACE
If the appliance is to be fitted on a wall of combustible material,
There is no requirement to protect the wall.
3A.9 TIMBER FRAMED BUILDINGS
If the appliance is to be fitted in a timber framed building, it
should be fitted in accordance with I.S. 813 and local Building
Regulations.
The Institute of Gas Engineers publication (IGE/UP/7) 'Guide
for Gas Installations in Timber Frame Buildings' gives specific
advice on this type of installation.
3A.10 WATER TREATMENT
Vokera recommend that water treatment be carried out in ac-
cordance with the Benchmark Guidance on water treatment
in central heating systems. If water treatment products are to
be used, then they must be entirely suitable for use with an
aluminium heat exchanger. Any water treatment product, must
be administered in strict accordance with the manufacturer's
instructions.
If the app
liance is to be installed to an existing system; water
treatment and flushing of the complete heating system should
be carried out in accordance with BS 7593 and the Benchmark
Guidance on water treatment in central heating systems.
3A.11 SHOWERS
If the appliance is intended for use with a shower, the shower
must be thermostatically controlled and be suitable for use with
a combination boiler.
3A.12 DECLARATION OF CONFORMITY
A Declaration of Conformity (as defined in I.S. 813) must be
provided on completion of the installation.
A copy of the declaration must be given to the responsible
person and also to the gas supplier if required.
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