7
Fig. 4A
Fig. 4
NOTE
●
The combined feed and vent pipe must rise continu-
ously and be unrestricted.
●
The diameter of the combined feed and vent pipe shall
be 22mm.
●
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 fl oat 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.
3.6.2 AUTOMATIC BY-PASS
Vokera recommend that an automatic bypass is installed
to ensure the required minimum fl ow-rate is achieved at
all times. Additionally, the design of the system and its
controls should ensure that an adequate temperature
differential is met, and should be such that it prevents
boiler ‘cycling’.
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 fi lling
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 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.
3.8 MOUNTING ON A COMBUSTIBLE
SURFACE
If the appliance is to be fi tted on a wall of combustible
material, a sheet of fi reproof material must protect the wall.
3.9 TIMBER FRAMED BUILDINGS
If the appliance is to be fi tted in a timber framed building,
it should be fi tted in accordance with the Institute of Gas
Engineers publication (IGE/UP/7) ‘Guide for Gas Instal-
lations 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 - includ-
ing 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
(fi g.4)
The appliance ‘fl ow’ and ‘return’ connections can be
confi gured to suit the following:
1. Top outlet connection
2. Bottom outlet connection
3. Top (fl ow), bottom (return) connection
4. Top (return) bottom (fl ow) 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 confi gured as shown
in fi g. 4A using a 22mm combined feed and vent pipe.
