7
British Gas 4100 & 4125 RD2 -
Installation & Servicing
GENERAL
GAS SUPPLY
The local gas supplier should be consulted, at the installation
planning stage, in order to establish the availability of an
adequate supply of gas. An existing service pipe must NOT be
used without prior consultation with the local gas supplier.
The boiler is to be installed only on a gas supply with a
governed meter.
A gas meter can only be connected by the local gas supplier or
by a local regional contractor.
Check that the appliance is suitable for the proposed gas supply.
An existing meter should be checked, preferably by the gas
supplier, to ensure that the meter is adequate to deal with the rate
of gas supply required. A minimum gas pressure of
20 mbar MUST be available at the boiler inlet, with the boiler operating.
Installation pipes MUST be fitted in accordance with BS. 6891.
Pipework from the meter to the boiler MUST be of an adequate
size. Both 100 and 125 models should be piped in 22mm
minimum. The final metre may be run in 15mm if it is visible.
The complete installation MUST be tested for gas soundness
and purged as described in the above code.
FLUE INSTALLATION
Some pluming may occur at the termination, so terminal
positions where this could cause a nuisance should be avoided.
The flue must be installed in accordance with the
recommendations of BS.5440-1:2000. The following notes are
intended for general guidance:-
1. The boiler MUST be installed so that the terminal is exposed
to external air.
2. It is important that the position of the terminal allows the free
passage of air across it at all times.
3. Minimum acceptable spacings from the terminal to
obstructions and ventilation openings are specified in Table 3.
4. Where the lowest part of the terminal is fitted less than 2m
(6'6") above a balcony, above ground or above a flat roof to
which people have access then the terminal MUST be
protected by a purpose designed guard.
Terminals guards are available from boiler suppliers - ask
for TFC Flue Guard, Model K1. In case of difficulty seek
advice from:
Grasslin (UK) Ltd., Tower House,
Vale Rise, Tonbridge, Kent TN9 1TB
Telephone No. 01732 359 888, Fax No. 01732 354 445
www.tfc-group.co.uk
Ensure that the guard is fitted centrally.
5. The air inlet/products outlet duct and the terminal of the
boiler MUST NOT be closer than 25mm (1") to combustible
material. Detailed recommendations on the protection of
combustible material are given in BS.5440-1:2000.
IMPORTANT
It is absolutely ESSENTIAL to ensure, in practice, that products
of combustion discharging from the terminal cannot re-enter the
building or any other adjacent building through ventilators,
windows, doors, other sources of natural air infiltration or forced
ventilation/air conditioning. If this should occur, the appliance
MUST be turned OFF, labelled 'unsafe' and corrective action
taken.
TERMINAL
WARNING
For top outlet installation the flue terminal MUST always be in
the horizontal position (not available on 125 model).
The terminal assembly can be adapted to accommodate various
wall thicknesses. Refer to Frames 11 & 28.
AIR SUPPLY
Detailed recommendations for air supply are given in
BS.5440:2. The following notes are for general guidance:
1. It is NOT necessary to have a purpose provided air vent in
the room or internal space in which the boiler is installed.
2. If the boiler is to be installed in a cupboard or compartment,
permanent air vents are required (for cooling purposes) in
the cupboard/compartment, at both high and low levels. The
air vents must either communicate with room/internal space,
or be direct to outside air. The minimum effective areas of
the permanent air vents, required in the cupboard/
compartment, are specified as follows and are related to
maximum rated heat input.
3. Both air vents MUST communicate with the same room or
internal space or MUST be on the same wall to outside air.
4. In siting the air vents care must be taken to avoid the
freezing of pipework.
Table 4 - High and low vent areas
Boiler
Air from room/internal
Air direct from
space cm
2
(in.
2
)
outside cm
2
(in.
2
)
High level
Low level
High level Low level
4100
354 (55)
354 (55)
177 (28)
177 (28)
4125
438 (68)
438 (68)
219 (34)
219 (34)
Table 3 - Balanced flue terminal position
Terminal Position
Minimum Spacing
1a. Directly BELOW an opening, air brick,
opening window, etc.
300 mm (12")
1b. Directly ABOVE an opening, air brick,
opening window, etc.
300 mm (12")
1c. HORIZONTALLY to an opening,
air brick,opening window, etc.
300 mm (12")
2. Below guttering, drain pipes or soil
pipes
75 mm
( 3")
3. Below eaves
200 mm
( 8")
4. Below balconies or a car port roof
200 mm
( 8")
5. From vertical drain pipes or soil pipes
150 mm
( 6")
6. From an internal or external corner or
to a boundary alongside the terminal
300 mm (12")
7. Above adjacent ground, roof or
balcony level
300 mm (12")
8. From a surface or a boundary facing
the terminal
600 mm (24")
9. From a terminal facing a terminal
1200 mm (48")
10. From an opening in a car port
(e.g. door or window) into dwelling
1200 mm (48")
11. Vertically from a terminal on the
same wall
1500 mm (60")
12. Horizontally from a terminal on the wall
300 mm (12")
