5
Mynute
A compartment used to enclose the appliance
must be designed and constructed specifically for
this purpose. An existing compartment/cupboard
may be utilised provided that it is modified to suit.
Details of essential features of compartment/
cupboard design, including airing cupboard in-
stallations, are given in BS 6798. This appliance
is not suitable for external installation.
3.3
GAS SUPPLY
The gas meter – as supplied by the gas supplier
– must be checked to ensure that it is of adequate
size to deal with the maximum rated input of all
the appliances that it serves. Installation pipes
must be fitted in accordance with BS 6891. Pipe
work from the meter to the appliance must be of
adequate size. Pipes of a smaller size than the
appliance gas inlet connection must not be used.
The installation must be tested for soundness in
accordance with BS 6891.
If the gas supply serves more than one appliance,
it must be ensured that an adequate supply is
maintained to each appliance when they are in
use at the same time.
3.4
FLUE SYSTEM
The terminal should be located where the disper-
sal 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 (fig. 4).
In a cold and/or humid water, water vapour may
condense on leaving the terminal; the effect of
such pluming must be considered.
If installed less than 2 metres 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 BS 5440 Part 1, when the terminal is 0,5
metres (or less) below plastic guttering or 1 metre
(or less) below painted eaves.
3.5
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.
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.
control valve
temporary
connection
control valve
flow/return pipe
double check
valve
supply pipe
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,
consequently there is no requirement for an ex-
ternal by-pass, however 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 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.
3.6.6
FILLING POINT (fig. 5)
A method for initial filling of the system and
replacing water lost during servicing etc. has
been provided. This method of filling must comply
with the current Water Supply (Water Fittings)
Regulations 1999 and Water Bylaws 2000
(Scotland). Fig. 5 shows a widely accepted method.
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 (fig. 5A). 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.
Fig. 5