25
4.6.7 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. 7
).
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.
4.6.8 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.
4.7 ELECTRICAL SUPPLY
The appliance is supplied for operation on 230V @ 50Hz electrical
supply; it must be protected with a 3-amp fuse (supplied). 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 3mm. The switch must only supply the appliance and its
corresponding controls, i.e. time clock, room thermostat, etc.
Alternatively an un-switched shuttered socket with a fused 3-pin
plug both complying with BS 1363 is acceptable.
Warning!
This appliance must be earthed.
4.8 MOUNTING ON A COMBUSTIBLE
SURFACE
The appliance can be mounted on a wall of combustible material
without any requirement to fit any additional protective (fire-
resistant) material.
4.9 TIMBER FRAMED BUILDINGS
If the appliance is to be fitted in a timber framed building, it
should be fitted in accordance with the Institute of Gas Engineers
publication (IGE/UP/7) ‘Guide for Gas Installations in Timber
Frame Buildings’.
4.10 WATER TREATMENT
Vokera recommend that water treatment be carried out in
accordance 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 a stainless-steel heat exchanger. Any water treatment
product, must be administered in strict accordance with the
manufacturer’s instructions.
If the appliance 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.
4.11 SHOWERS
If the appliance is intended for use with a shower, the shower
should be thermostatically controlled and be suitable for use
with a combination boiler.
This appliance must be installed by a competent person in
accordance with and defined by, the Standard Specification
(Domestic Gas Installations) Declaration (I.S. 813).
flow/return
pipe
control
valve
temporary
connection
control
valve
supply
pipe
double
check valve
Fig. 6
Make-up vessel
or tank
Automatic
air-vent
Non-return
valve
Stopcock
5.0 metres minimum
Heating
return
Fig. 7
