7
3.5
AIR SUPPLY
The following notes are intended for general guid-
ance 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 re-
quired.
3.6
WATER CIRCULATION
Detailed recommendations are given in BS 5449
Part 1 and BS 6798. The following notes are for
general guidance only.
3.6.1
PIPEWORK
It is recommended that copper tubing to BS 2871 Part
1 is 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 atten-
tion should be paid to pipes passing through
ventilated areas such as under floors, loft space,
and void areas.
3.6.2
AUTOMATIC BY-PASS
The appliance has a built-in automatic by-pass.
However it may be necessary to fit an external by-
pass should the design of the heating system
require such. In any case, the design of the system
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 filling of the system.
3.6.5
EXPANSION VESSEL
The appliance has an integral expansion vessel to
accommodate the increased volume of water
when the system is heated. It can accept up to 10
litres within the system, generally this is suffi-
cient, however if the system has an unusually high
water content, it may be necessary to provide
additional expansion capacity (see 6.24).
3.6.6
FILLING POINT
A method for initial filling of the system and
replacing water lost during servicing etc. has been
provided. This method of filling complies with the
current Water Supply (Water Fittings) Regulations
1999 and Water Bylaws 2000 (Scotland).
3.6.7
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. 5). The cold feed from the
make-up vessel or tank must be fitted with an
approved non-return valve and stopcock for isola-
tion purposes. The feed pipe should be connected
to the return pipe as close to the boiler as possible.
3.6.8
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.
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 con-
trols, i.e. time clock, room thermosta, etc. Alterna-
tively an un-switched shuttered socket with a
fused 3-pin plug both complying with BS 1363 is
acceptable.
3.8
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.
3.9
MOUNTING ON A COMBUSTIBLE SURFACE
If the appliance is to be fitted on a wall of combus-
tible material, a sheet of fireproof material must
protect the wall.
3.10
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”.
Make-up vessel
or tank
Automatic
air-vent
Non-return
valve
Stopcock
5.0 metres minimum
Heating
return
Fig. 5
