7
3.6.3 DRAIN COCKS
These must be located in accessible positions to facilitate
draining of the appliance and all water pipes connected to
the appliance. The drain cocks must be manufactured in
accordance with BS 2879.
3.6.4 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.
3.7 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 3,5mm (3° high-voltage
category). The switch must only supply the appliance and
its corresponding controls, i.e. time clock, room thermo-
stat, etc. Alternatively an un-switched shuttered socket
with a fused 3-pin plug both complying with BS 1363 is
acceptable.
3.8 MOUNTING ON A COMBUSTIBLE
SURFACE
If the appliance is to be fitted on a wall of combustible
material, a sheet of fireproof material must protect the wall.
3.9 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’.
3.10 INHIBITORS
Vokera recommend that an inhibitor - suitable for use with
aluminium heat exchangers - is used to protect the boiler
and system from the effects of corrosion and/or electrolytic
action. The inhibitor must be administered in strict
accordance with the manufacturers instructions*.
*Water treatment of the complete heating system - including
the boiler - should be carried out in accordance with BS
7593 and the Domestic Water Treatment Association’s
(DWTA) code of practice.
3.11 APPLIANCE PIPEWORK CONFIGURATION (fig.4)
The appliance ‘flow’ and ‘return’ connections can be
configured to suit the following:
1. Top outlet connection
2. Bottom outlet connection
3. Top (flow), bottom (return) connection
4. Top (return) bottom (flow) connection.
3.11.1 FEED & VENT PIPEWORK
The feed and vent pipe work from the boiler to the F&E
(Feed & Expansion) tank should be configured as shown
in fig. 4A using a 22mm combined feed and vent pipe.
NOTE
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The combined feed and vent pipe must rise continuously
and be unrestricted.
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The diameter of the combined feed and vent pipe shall
be 22mm.
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The minimum distance from the top of the boiler to the
bottom of the F&E tank shall be no less than 1-metre,
whilst the maximum distance shall be no greater than
30-metres.
The supply of water to the F&E tank should be taken from
the mains water supply via a suitable float operated valve,
whilst the supply from the F&E tank to the boiler/heating
circuit (via the combined feed and vent pipe) shall be
unrestricted.
3.11.2 ALTERNATIVE CLOSE-COUPLED ARRANGEMENT
If necessary or if preferred, a close-coupled arrangement
for the feed and expansion pipe work can be used as an
alternative to a combined feed and vent pipe. The
configuration of the close-coupled pipe work shall be as
shown in figure 4B.
Fig. 4A
Fig. 4
