ideal British Gas 100 RD2 User guide
British Gas:
(Any internal reference to British Gas applies equally to Scottish Gas)
The British Gas RD2 is a range of cast iron floor standing gas central heating boilers.
A complete range of natural gas models is available.
The ideal replacement boiler...
Easy to install, easy to operate and easy to service. The British Gas RD2 really is the
ultimate replacement floor standing range - you can depend on it.
Proven reliability...
Proven cast iron heat exchanger engineered and refined to be the most dependable
floor standing boiler ensuring totally calm operation and quiet running, whatever the
system demands.
Complete range...
There are 7 models in the range. All models include an overheat thermostat and a Flue
Directional kit for side and top outlet installations.
Full system suitability...
All models are suitable for connection to pumped open vent central heating systems,
pumped central heating combined with pumped or gravity indirect domestic hot water
supply systems. They can also be used on sealed water systems.
Free Three Star Service Cover:
In addition to the guarantee, we will provide absolutely free a British Gas Services
Three Star Service Cover agreement to cover your complete new system during the
first year. The benefits of this cover include priority attention and a 24 hours a day 365
days a year helpline. Full details of the terms and conditions for Three Star Cover
schemes are available separately on request.
2
British Gas 100 & 125 RD2 - Installation & Servicing
GENERAL
Table 1 - General Data
Boiler Size 100 125
Gas Supply Connection in. BSP Rc 1/2 (1/2)
Number of Boiler Sections 4 5
Flow and Return Connections Rc 1 (1" BSP)
MAXIMUM Static Water Head m (ft.) 30.5 (100) (3 bar)
MINIMUM Static Water Head m (ft.) 1.0 (3.3)
Electrical Supply (Power Consumption) 230 V ~ 50 Hz (150 W)
Fuse Rating External 3 A Internal 2A to BS4265
Water Content litre (gal.) 9.8 (2.1) 12.2 (2.7)
Dry Weight kg. (lb.) 113 (249) 136 (300)
Boiler Size Height mm (in.) 850 (33.5)
Width mm (in.) 440 (17.4)
Depth mm (in.) 533 (21.0) 600 (23.6)
Gas Type Natural 2 H
Gas Supply Pressure 20 mb
Flue duct diameter mm (in.) 100 (4.0)
Flue duct length (max) m (ft) 2 (6.5) 1 (3.25)
Table 2 - Performance Data
Boiler Size 100 125
Boiler Input Nett CV kW (Btu/h) 33.0 (112 600) 41.3 (141 000)
Gross CV kW (Btu/h) 36.6 (125 000) 45.8 (156 300)
Gas Consumption l/s (ft.
3
/h) 0.95 (120.4) 1.18 (150.5)
Boiler Output to Water
kW (Btu/h) 29.3 (100 000) 36.6(125 000)
Burner Setting Pressure (hot)
mbar (in w.g.) 11.5 (4.6) 13.2 (5.3)
Seasonal Effiiciency (SEDBUK)* Band[ ]% D[77.6]% D[77.9]%
* The value is used in the UK Government's Standard Assessment Procedure (SAP) for energy rating of dwellings.
The test data from which it has been calculated have been certified by BG plc 0087.
Note.
Gas consumption is calculated using a calorific value of 38.7
3
(1038 Btu/ft3) gross or 34.9 MJ/m3 (935 Btu/ft3) nett. To
MJ/m
obtain the gas consumption at a different calorific value:-
a. For l/s - divide the gross heat input (kW) by the gross C.V.
of the gas (MJ/m3)
3
b. For ft
/h - divide the gross heat input (Btu/h) by the gross
C.V. of the gas (Btu/ft3)
c. The appliance is preset at the factory to the nominal rating.
CAUTION.
To avoid the possibility of injury during the installation, servicing or cleaning of
Key to symbols
GB = United Kingdom
(Countries of destination)
PMS = Maximum operating pressure of water
C12 = A room sealed appliance designed for connection via
ducts to a horizontal terminal which admits fresh air to
the burner and discharges the products of combustion
to the outside through orifices which, in this case, are
concentric. The fan is down stream of the combustion
chamber.
I
= An appliance designed for use on 2nd Family gas,
2H
Group H only.
this appliance, care should be taken when handling edges of sheet steel components.
British Gas 100 & 125 RD2 - Installation & Servicing
3
GENERAL
CONTENTS
Air Supply. ..................................................................... 7
Boiler Assembly - Exploded view ............................. 12
Boiler Clearances ......................................................... 6
Electrical Connections............................................... 23
Electrical Diagrams ............................................ 23 - 26
Electrical Supply ........................................................... 8
Extension Ducts - Fitting ........................................... 21
Fault Finding ............................................................... 38
Flue Fitting ............................................................. 15-20
Flue Installation ............................................................ 7
Gas Safety Regulations ............................................... 5
Gas Supply .................................................................... 7
Initial Lighting ............................................................. 27
Installation ................................................................... 12
Mandatory Requirements ......................................... 5-7
Pump Systems .............................................................. 9
System Diagrams (Electrical) .................................... 25
Terminal Guards. .......................................................... 7
Water Connections ........................................ 5, 15 & 22
Water Circulation .......................................................... 8
Water Systems .............................................................. 9
BENCHMARK LOG BOOK DETAILS
Boiler Page
Make and model ........................................................ 4
Appliance Serial No. on Data Badge ........................ 9
Controls ............................................... as applicable
Forall boilers
Flushing to BS.7593 .................................................. 8
Inhibitor ...................................................................... 8
Gas inlet working pressure ....................................... 6
Burner operating pressure ........................................ 3
Heat input .......................................... to be calculated
Temperature differential .............measure and record
For combination boilers only ................. Not applicable
For domestic hot water mode ................ Not applicable
For condensing boilers ........................... Not applicable
For all boilers: complete, sign & hand over to customer
British Gas RD2
100 RD2 G.C. No. 41 387 58
125 RD2 G.C. No. 41 387 59
Natural Gas only Appliance type: C
Certified - P.I. No. 87BL30 Destination Countries: GB.
INTRODUCTION
British Gas RD2 above range is of floor standing, fanned
flue gas boilers. They are rated to provide central heating
outputs of 29.3 kW (100,000 Btu/h) to
36.6 kW (125,000 Btu/h).
The boiler has a cast iron heat exchanger and is supplied
fully assembled, complete with a white enamelled mild
steel casing.
A door at the top of the casing front panel hinges down,
revealing the boiler thermostat control.
The boilers are supplied with kits for rear, side and top
(100 only) flue outlets.
The boilers are suitable for connection to open-vented
systems and sealed water systems.
The systems may be:
z pumped or gravity circulating indirect DHW only
z pumped central heating only
z pumped central heating combined with either a pumped
or gravity circulating indirect DHW circuit.
The diagnostic controls within the boiler are capable of
communicating key operational data to a central computer data
processing system via the house ring main and public telephone
system known as Remote Appliance Diagnostic System (or
RADS).
RADS can identify actual failure, or predict imminent failure of
components and specify the corrective procedures to the British
Gas Service Engineer.
To enable the system to operate, a remote mounted interface
(Gateway) is required to receive and transmit data from the
boiler.
Without this facility, the boiler operates as standard fanned flued
boiler.
OPTIONAL EXTRA KITS
Extension Duct kit To extend standard flue.
90o Flue Elbow Kit
12
For assistance see Technical Helpline on the back page
NOTE TO THE INSTALLER:
INSTRUCTIONS ADJACENT TO THE GAS METER.
ALSO COMPLETE THE BENCHMARK LOG BOOK
AND GIVE THIS TO THE CUSTOMER.
4
LEAVE THESE
British Gas 100 & 125 RD2 - Installation & Servicing
GENERAL
GAS SAFETY
Current Gas Safety (Installation and Use)
Regulations, or the rules in force.
It is law that all gas appliances are installed by a CORGI
registered installer in accordance with the above regulations.
Failure to install appliances correctly could lead to prosecution.
It is in your own interest, and that of safety, to ensure the law is
complied with.
The installation of the boiler MUST also be in accordance with
the latest I.E.E (BS 7671) Wiring Regulations, local building
regulations, bylaws of the local water authority, the Building
Regulations and Building Standards (Scotland) and any
relevant requirements of the local authority.
Detailed recommendations are contained in the following
British Standard Codes of Practice:
BS. 6891 Low pressure installation pipes.
BS. 6798 Installation of gas fired hot water boilers of rated
input not exceeding 60 kW.
BS. 5449:1 Forced circulation hot water systems (small bore
and microbore domestic central heating
systems).
BS. 5546 Installation of gas hot water supplies for
domestic purposes (2nd Family Gases).
BS. 5440: 1 Flues for gas appliances of rated input not
exceeding 70 kW.
BS. 5440: 2 Ventilation for gas appliances of rated input not
exceeding 70 kW.
BS 7593 Treatment of water in Domestic Hot Water
Central Heating Systems.
Health and Safety Document No. 635.
The Electricity at Work Regulations, 1989.
Manufacturer’s notes must NOT be taken in any way as
overriding statutory obligations.
IMPORTANT. These appliances are certificated by the BG
Technology Certification Services for safety and performance.
It is important, therefore, that no external control devices, e.g.
flue dampers, economisers etc., are directly connected to
these appliances unless covered by these Installation and
Servicing Instructions or otherwise recommended by British
Gas in writing. If in doubt please enquire.
Any direct connection of a control device not approved by
British Gas could invalidate the certification and the normal
appliance warranty. It could also infringe the Gas Safety
Regulations and the above regulations or other statutory
requirements.
SAFE HANDLING OF SUBSTANCES
Care should be taken when handling the boiler insulation
panels, which can cause irritation to the skin. No asbestos,
mercury or CFC's are included in any part of this boiler.
LOCATION OF BOILER
The boiler must be installed on a flat and level floor, capable of
adequately supporting the weight of the boiler and any ancillary
equipment.
The boiler may be fitted on a combustible floor.
Insulation is not necessary, unless required by the local
authority.
The boiler must not be fitted outside.
Timber Framed Buildings
If the boiler is to be fitted in a timber framed building it should
be fitted in accordance with the Institute of Gas Engineers
document IGE/UP/7 : 1998.
1
BOILER WATER CONNECTIONS
1. This appliance is NOT suitable for use in a direct hot water system.
2. The boiler is suitable to be used on a sealed system. Overheat
Thermostat is fitted as standard.
Dimension A B
100 299mm (11
125 373mm (14
3/4") 533mm (21")
5/8") 600mm (23 5/8")
British Gas 100 & 125 RD2 - Installation & Servicing
5
GENERAL
Bathrooms
The boiler may be installed in any room or internal space,
although particular attention is drawn to the requirements of the
current I.E.E. (BS 7671) Wiring Regulations and, in Scotland,
the electrical provisions of the building regulations applicable in
Scotland with respect to the installation of the boiler in a room or
internal space containing a bath or shower.
Where a room-sealed appliance is installed in a room
containing a bath or shower then the appliance and any
electrical switch or appliance control utilising mains electricity
should be so situated that it cannot be touched by a person
using the bath or shower.
Where installation will be in an unusual location, special
procedures may be necessary and BS.6798 gives detailed
guidance on this aspect.
Compartment Installations
A compartment used to enclose the boiler MUST be designed
and constructed specially for this purpose.
2
FLOOR MOUNTING AND BOILER CLEARANCES
Flammable materials must not be placed in close proximity to
the appliance. Materials giving off flammable vapours must
not be stored in the same room as the appliance.
Floor mounting
1. The floor must be flat, level and of suitable load bearing
capacity.
2. The back of the boiler may be fitted up to the wall.
Boiler clearances
The minimum overall dimensions of the space in which the boiler
is to operate and to facilitate servicing are as follows:-
An existing cupboard or compartment may be used, providing it
is modified for the purpose.
In both cases details of essential features of cupboards/
compartment design, including airing cupboard installation, are
to conform to the following:
zz
z BS. 6798.
zz
zz
z The position selected for installation MUST allow
zz
adequate space for servicing in front of the boiler
and for air circulation around the boiler.
Side clearance is only necessary for installation. The amount
of side clearance will depend upon the type of connection
used.
z This position MUST also permit the provision of a satisfactory
flue termination.
z For the minimum clearances required for safety, and
subsequent service, see Frame 2.
Additional space will be required for installation,
depending upon site conditions.
IMPORTANT.
In order to facilitate gas connection, a clearance of at
least 100 mm (4") must be available at either the left
hand side or the right hand side DURING installation.
Refer to Frame 31.
In addition a MINIMUM clearance of 533 mm (21") MUST
be available at the front of the boiler, for servicing.
Boiler Flue Overall Space Dimension Min Side Clearance 'A'
Model Length Depth Height Width Width Rear Flue Side/Top Flue
Rear Flue Side/Top Flue
(
114 to 600
100 600 to 2000 533 (21") 870 (34
(23 5/8 to 78 3/4")
114 to 600 (
125 600 to 1000 600
23 5/8" to 39 1/4")
(
4 1/2 to 23 5/8
4 1/2 to 23 5/8
6
") 533 (21") 870 (34 1/4") 460 (18 1/8") 510 (20 1/8") 10 (3/8") 35(1 3/8")
1/4") 510 (20 1/8") 510 (20 1/8") 35 (1 3/8") 35(1 3/8")
") 600 (23 5/8") 870 (34 1/4") 550 (21 5/8") 550 (21 5/8") 55 (2 1/4") 55(2 1/4")
(23 5/8") 870 (34 1/4") 550 (21 5/8") 550 (21 5/8") 55 (2 1/4") 55(2 1/4")
British Gas 100 & 125 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.
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 spacing from the terminal to
obstructions and ventilation openings are specified in
Table 3.
Table 3 - Balanced flue terminal position
Terminal Position
1. Directly below or alongside an
opening window, air vent or other
ventilation opening 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 75 mm ( 3")
6. From internal or external corners 300 mm ( 12")
7. Above adjacent ground, roof or
balcony level 300 mm (12")
8. From a surface 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")
Minimum Spacing
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
Tower Flue Guard, Model K1. In case of difficulty seek
advice from:
Tower Flue Components Ltd.,
Vale Rise, Tonbridge, Kent TN9 1TB
Telephone No. 01732 351 555
Ensure that the guard is fitted centrally.
5. Where the terminal is fitted within 1000mm (39
plastic or painted gutter or 500mm (19 1/2") of painted eaves
then an aluminium shield at least 1000mm (39 1/2") long
should be fitted to the underside of the gutter or painted
surface.
6. 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: 1990.
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.
1/2") of a
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
High level Low level High level Low level
100 354 (55) 354 (55) 177 (28) 177 (28)
125 438 (68) 438 (68) 219 (34) 219 (34)
2
(in.2) outside cm2 (in.2)
British Gas 100 & 125 RD2 - Installation & Servicing
7
GENERAL
WATER CIRCULATION SYSTEM
The boiler must NOT be used for direct hot water supply or for
sealed systems. The boiler is suitable for connection to pumped
open vent central heating systems, pumped central heating
combined with pumped or gravity indirect domestic hot water
supply systems.
The boiler is NOT suitable for gravity heating systems. The
hydraulic resistances of the boilers at maximum output with 11
(20 oF) temperature differentials are shown in the graph below.
Maximum boiler operating temperature should be 82OC (180OF).
The central heating system should be in accordance with
BS. 6798 and, in addition, for smallbore and microbore
systems, BS. 5449:1.
The domestic hot water system, if applicable, should be in
accordance with the relevant recommendations of BS. 5546.
Copper tubing to BS. 2871:1 is recommended for water carrying
pipework.
The hot water storage cylinder MUST be of the indirect type and
should preferably be manufactured of copper.
Single feed, indirect cylinders are not recommended and MUST
NOT be used on sealed systems.
The hot water cylinder and ancillary pipework not forming part of
the useful heating surface should be lagged to prevent heat loss
and any possible freezing - particularly where pipes run through
roof spaces and ventilated underfloor spaces.
IMPORTANT
The boiler must be vented. If venting cannot be done via a flow
connection a separate vent MUST be fitted by the installer.
Draining taps MUST be located in accessible positions, which
permit the draining of the whole system - including the boiler and
hot water storage vessel. They should be at least
nominal size and be in accordance with BS. 2879.
If required, a drain tap (not supplied) may be fitted to an unused
bottom (1" BSP) tapping on the front of the boiler.
Water Flow Rate and Pressure Loss
1/2" BSP
FLOW RATE (gals/hr.)
100
600
125
140
100
60
200 400
125
100 &
PRESSURE LOSS (mbar)
20
10
20
30 40
50
FLOW RATE (l/min.)
Dotted lines indicate flow rates equivalent
to a temperature rise of 11
o
C (20 oF)
o
5.0
4.0
3.0
2.0
1.0
WATER TREATMENT
The British Gas RD2 incorporates a cast iron heat
exchanger. As part of the installation the central heating
system should be thoroughly flushed with appropriate
water treatment in order to comply with BS7593:1992
British Gas recommend the use of Fernox or Betz
C
Dearborn water treatment products which must be used in
accordance with the manufacturers instructions. For
further information contact :
Fernox Manufacturing. Co. Ltd., Tandem House,
Marlowe Way, Croydon, Surrey CRO 4XS,
tel. 0870 5601 5000
or
Betz Dearborn Ltd., Widnes, Cheshire,
tel. 0151 424 5351
IMPORTANT. ANY OTHER TREATMENT FOR THIS
PRODUCT MAY RENDER THE GUARANTEE OF
BRITISH GAS INVALID.
Notes.
1. If an inhibitor is used, and in hard water areas where
treatment to prevent lime deposits is necessary, it is
most important that the water treatment MUST be
maintained at the correct concentrations recommended
by the treatment manufacturer.
2. Artificially softened water must not be used in the
system, under any circumstances.
THERMOSTATIC RADIATOR VALVES
British Gas recommend that heating systems utilising full
thermostatic radiator valve control of temperature in individual
rooms should also be fitted with a room thermostat controlling
the temperature in a space served by radiators not fitted with
such a valve, as stated in BS. 5449.
When thermostatic radiator valves are used, the space heating
temperature control over a living / dining area or hallway having
a heating requirement of at least 10% of the boiler heat output
should be achieved using a room thermostat, whilst other rooms
are individually controlled by thermostatic radiator valves.
However, if the system employs thermostatic radiator valves on
all radiators or two port valves without end switches then a
bypass must be fitted in order to ensure a flow of water should
all the valves be in the closed position.
ELECTRICAL SUPPLY
WARNING. The appliance MUST be efficiently earthed.
Wiring external to the appliance MUST be in accordance with
the current I.E.E. (BS 7671) Wiring Regulations and any local
regulations which apply.
The boiler is supplied for 230 V ~ 50 Hz single phase. The fuse
rating is 3A.
Connection must be made in a way that allows complete
isolation of the electrical supply - such as a double pole switch,
PRESSURE LOSS (ft. water)
having a 3mm (
and socket serving only the boiler and system controls.
The means of isolation must be accessible to the user after
installation.
For bathroom installations the point of connection to the mains
Mex 1341 -1
must be situated outside the bathroom.
1/8") contact separation in both poles, or a plug
8
British Gas 100 & 125 RD2 - Installation & Servicing
GENERAL
3
MINIMUM REQUIREMENTS Fully pumped systems
1. Open vent and cold feed connections must be made to the
boiler flow and return tappings according to the options
shown in Frame 12.
2. The boiler is assumed to be the highest point of the
circulating system.
3. The circulating pump is positioned on the FLOW and the
vertical distance, between the pump and feed/ expansion
tank, must comply with the pump manufacturer's minimum
requirements, to avoid cavitation. Should these conditions
not apply, either lower the pump position or raise the feed/
expansion tank above the minimum requirements of
British Gas Services.
4. The water velocity through the boiler flow / return pipes is
assumed to be below 1.5 m/s (5 ft./s), whilst the pump flow
rate is set to provide a temperature difference of
o
C (20 oF) across the boiler flow / return, at design input.
11
5. This information is intended as a GUlDE ONLY and cannot
take into account instantaneous changes in head caused
by the operation of motorised valves, pumps etc.
Due allowance MUST be made if surging is liable to occur.
If in any doubt, contact British Gas Services.
4
GRAVITY HOT WATER & PUMPED CENTRAL HEATING
1. Separate flow and return connections are used for each
service. All possible configurations are given in Frame 12
and ONLY those shown should be used.
2. The schematic pipework graph is based on the assumption
that NO MORE than 8 elbows are used in the gravity loop,
including entry to the boiler.
3. For each extra elbow in excess of 8 (R) MUST be reduced by
300 mm (12") or (H) increased by 100 mm (4")
4. Whatever value is selected for (R), the value of (H) MUST be
at least that indicated by the graph.
(R) = the horizontal distance between the centre line of the
cylinder and the boiler tappings used - measured along
the pipe run.
(H) = the vertical distance between the top of the boiler and
the base of the cylinder.
Notes.
a. Flow and return pipes should rise vertically on leaving the
boiler.
b. Horizontal pipes should be ABOVE ceiling level and as short
as possible.
c. A MINIMUM inclination of 25 mm per 3 m run (1" per 10') is
required to avoid air locks.
British Gas 100 & 125 RD2 - Installation & Servicing
If the above conditions cannot be met pumped primaries should
be used.
9
5
SEALED SYSTEM REQUIREMENTS
Safety valve
Drain cock
Pressure gauge
GENERAL
Pump
Air vent
HEATING
CIRCUIT
Make-up vessel
(max. capacity
3 litres
)
Non-return
valve
Automatic
air vent
Hosepipe
(disconnect
after filling)
Hose
union
bib
tap
Water
supply
Mex 903
BOILER
Expansion
vessel
Double check valve
Note. The method of filling, refilling, topping up or flushing
sealed primary hot water circuits from the mains via a
temporary hose connection is only allowed if acceptable to the
local water authority.
1. General
a. The installation must comply with the requirements of
BS.6798 and BS.5449.
b. The installation should be designed to work with flow
temperatures of up to 82
o
C.
c. All components of the system, including the heat exchanger
of the indirect cylinder, must be suitable for a working
pressure of 3 bar (45 lb/in2) and temperature of 110oC. Care
should be taken in making all connections so that the risk
of leakage is minimised.
2. Safety Valve
A spring loaded safety valve complying with the relevant
requirements of BS.6759 must be fitted in the flow pipe, as
close to the boiler as possible and with no intervening valve
or restriction. The valve should have the following features:
a. A non-adjustable pre-set lift pressure not exceeding 3 bar
(45 lb./in
2
)
b. A manual testing device.
c. Provision for connection of a discharge pipe. The valve or
discharge pipe should be positioned so that the discharge
of water or steam cannot create a hazard to the occupants
of the premises or cause damage to electrical components
and wiring.
3. Pressure Gauge
A pressure gauge covering at least the range 0-4 bar (0-60
2
) must be fitted to the system. The gauge should be
lb./in
easily seen from the filling point and should preferably be
connected at the same point as the expansion vessel.
BS.1010:2
Test cock
stop tap
Hose
connector
4. Expansion Vessel
a. A diaphragm type expansion vessel must be connected at
a point close to the inlet side of the pump, the connecting
pipe being not less than 15mm (
1/2" nominal) size and not
incorporating valves of any sort.
b. The vessel capacity must be adequate to accept the
expansion of the system water when heated to 110oC
(230oF)
c. The charge pressure must not be less than the static water
head above the vessel The pressure attained in the system
when heated to 110oC (230oF) should be at least 0.35 bar
(5lb/in2) less than the lift pressure of the safety valve.
For guidance on vessel sizing refer to the table in Frame 6.
For further details refer to BS.5449 and the British Gas
Corporation publication : Material and Installation
Specifications for Domestic Central Heating & Hot Water.
5. Cylinder
The cylinder must be either of the indirect coil type or a direct
cylinder fitted with an immersion calorifier which is suitable
for operating on a gauge pressure of 0.35 bar (5lb./in
excess of the safety valve setting. Single feed indirect
cylinders are not suitable for sealed systems.
6. Make-up Water
Provision must be made for replacing water loss from the
system, either:
a. From a manually fitted make-up vessel with a readily visible
water level. The vessel should be mounted at least 150mm
(6") above the highest point of the system and be
connected through a non-return valve to the system, fitted
at least 300mm (12") below the make-up vessel on the
return side of the domestic hot water cylinder or radiators.
b. Where access to a make-up vessel would be difficult by
pre-pressurisation of the system. Refer to 'Filling.'
2
) in
10
British Gas 100 & 125 RD2 - Installation & Servicing
GENERAL
6
SEALED SYSTEM REQUIREMENTS - continued
7. Mains Connection
There must be no direct connection to the mains water supply
or to the water storage tank supplying domestic water, even
through a non-return valve, without the approval of the local
water authority.
8. Filling
The system may be filled by one of the following methods:
a. Through a cistern, used for no other purposes, via a ball
valve permanently connected directly to a service pipe and
/ or a cold water distributing pipe.
The static head available from the cistern should be
adequate to provide the desired initial system design
pressure. The cold feed pipe from the cistern should include
a non-return valve and a stop valve with an automatic air
vent connected between them, the stop valve being located
between the system and the automatic air vent. The stop
valve may remain open during normal operation of the
system if automatic water make-up is required.
b. Through a self-contained unit comprising a cistern,
pressure booster pump (if required) and, if necessary, an
automatic pressure reducing valve and flow restrictor. The
cistern should be supplied through a temporary connection
from a service pipe or cold water distributing pipe.
This unit may remain permanently connected to the heating
system to provide limited automatic water make-up. Where
the temporary connection is supplied from a service pipe
or distributing pipe which also supplies other draw-off points
at a lower level then a double check valve shall be installed
upstream of the draw-off point.
c. Through a temporary hose connection from a draw-off tap
supplied from a service pipe under mains pressure. Where
the mains pressure is excessive a pressure-reducing valve
shall be used to facilitate filling.
The following fittings shall form a permanent part of the
system and shall be fitted in the order stated:
A stop valve complying with the requirements of
BS. 1010, Part 2 (the hose from the draw-off tap shall be
connected to this fitting).
A test cock.
A double check valve of an approved type.
• Thoroughly flush out the whole of the system with cold
water, without the pump in position.
• With the pump fitted, fill and vent the system until the
pressure gauge registers 1.5 bar (21.5lb/in
Examine for leaks.
• Check the operation of the safety valve by manually
raising the water pressure until the valve lifts. This
should occur within ± 0.3 bar (± 4.3lb/in
lift pressure.
• Release water from the system until the initial system
design pressure is reached.
• Light the boiler and heat the system to the maximum
working temperature. Examine for leaks.
• Turn off the boiler and drain the system while still hot.
• Refill and vent the system.
• Adjust the initial pressure to the required value.
2
).
2.
) of the pre-set
Sizing procedure for expansion vessels: The volume of the expansion vessel (litres) fitted to a sealed system shall not be
less than that given by the table below, multiplied by a factor of 0.8 (for flow temperatures of less than 88
Safety valve setting 3.0 bar 2.5 bar 2.0 bar
Vessel charge and initial 0.5 1.0 1.5 0.5 1.0 1.5 0.5 1.0
system pressure bar bar bar bar bar bar bar bar
Total water content of system Expansion vessel volume
(litres) (litres)
25 2.1 2.7 3.9 2.3 3.3 5.9 2.8 5.0
50 4.2 5.4 7.8 4.7 6.7 11.8 5.6 10.0
75 6.3 8.2 11.7 7.0 10.0 17.7 8.4 15.0
100 8.3 10.9 15.6 9.4 13.4 23.7 11.3 20.0
125 10.4 13.6 19.5 11.7 16.7 29.6 14.1 25.0
150 12.5 16.3 23.4 14.1 20.1 35.5 16.9 30.0
175 14.6 19.1 27.3 16.4 23.4 41.4 19.7 35.0
200 16.7 21.8 31.2 18.8 26.8 47.4 22.6 40.0
225 18.7 24.5 35.1 21.1 30.1 53.3 25.4 45.0
o
C).
250 20.8 27.2 39.0 23.5 33.5 59.2 28.2 50.0
275 22.9 30.0 42.9 25.8 36.8 65.1 31.0 55.0
300 25.0 32.7 46.8 28.2 40.2 71.1 33.9 60.0
Multiplying factors for
other system volumes 0.0833 0.109 0.156 0.094 0.134 0.237 0.113 0.20
British Gas 100 & 125 RD2 - Installation & Servicing
11
7
BOILER ASSEMBLY - Exploded View
100 shown with casing removed .
INSTALLATION
INSTALLATION
41
5
1
7
Tie rod
Mex 1852
42
Fan sensor
38
92
14
12
49
3
4
2
6A
Overheat sensor
Return sensor
Flow
6
sensor
6B
8
47
18
46
28
16
65
Data badge
LEGEND
1. Heat exchanger assembly.
2. Front section.
3. Centre section.
4. Section alignment rings and 'O' rings.
5. Back section.
6. Flow thermistor sensor pocket.
6A.Return thermistor sensor pocket.
6B.O/heat thermostat sensor pocket.
7. Distributor tube.
8. Combustion chamber.
12. Collector hood.
14. Fan assembly.
16. Front plate assy.
18. Burner manifold.
28. Gas cock.
38. Pressure switch.
41. Air inlet duct.
42. Turret access cover assy.
46. Boiler base plate.
47. Baseplate heat shield.
49. Flue baffle.
65. Control box.
92. Thermostat bush.
12
British Gas 100 & 125 RD2 - Installation & Servicing
INSTALLATION
8
UNPACKING
The boiler is supplied fully assembled in
Pack A, together with a standard flue
assembly for lengths up to 600mm (23 1/2")
rear or side flue outlet in Pack B.
Unpack and check the contents.
PACK 'A' CONTENTS
z Complete boiler assembly
z The Boiler Hardware Pack (listed
separately)
z The Flue Hardware Pack (listed
separately)
z These Installation/Servicing
Instructions
z User's Instructions.
z Template
FLUE PACK. Pack B Contents
z Duct cutting support - 2 off (cardboard )
z Terminal wall plate - 1 off.
z Terminal grille assy. - 1 off.
z Polyurethane foam seal 400 lg. - 1 off.
z No. 8 x 8 lg. Pozi pan hd. screws - 3 off.
complete boiler
assembly
FLUE HARDWARE PACK
z Flue extension tube (rear).
z Flue extension tube (side).
BOILER HARDWARE PACK
z 1" BSP plugs - 3 off.
z Distributor tube - 1 off.
z 28mm x 1"BSP male straight
adapter compression fitting - 3 off.
For connection to the boiler
PUMPED & GRAVITY flow /return
tappings.
z Flow sensor pocket -1 off.
z Return sensor pocket kit
comprising:
Hexagon bush - 1 off.
Sensor pocket - 1 off.
'O' ring - 1 off.
Heyco bush - 1 off.
M5 x 10mm Pozi screw - 3 off.
Washers - 3 off.
z O/heat thermostat pocket - 1off
z 1/2" square bar - 1 off.
z Cable tie - 4 off.
z Control thermostat knob - 1 off.
z M3 x 6mm Pozi pan screw- 1 off.
z Self tapping screw - 2 off.
z British Gas Logo- 1 off.
z Scottish Gas Logo - 1 off.
INSTALLATION
Flue terminal
9
BOILER CASING REMOVAL
To install the boiler the casing MUST be removed.
1. Undo the 2 screws and lift off the lower front panel.
2. Remove the 2 screws and lift off the grille assembly.
3. Release the 'Burner On' neon from the rear of the
control panel.
Terminal wall plate
z Flue extension tube (top).
z Elbow .
z Sealing ring.
z M5 wing nuts - 3 off.
z Side outlet plate.
z No. 10 x 2" lg. Rd Hd.wood
screws - 4 off.
z Wall plugs - 4 off.
Side outlet plate
4. Release the wiring harness leads from the edge clips
on the RH side panel.
5. Remove the 2 screws securing the control panel and
pull down to release the tabs from under the top
panel.
British Gas 100 & 125 RD2 - Installation & Servicing
13
10
BOILER CASING REMOVAL - continued
INSTALLATION
6. Release the screw securing the control box to the
baseplate and slide to the left to release the box.
7. Remove the 2 screws securing the top panel to the
sides.
8. Draw the top panel forward and lift it off the boiler.
9. Remove the 2 screws securing the LH side panel to
the turret front panel and baseplate.
10. Pull the panel forward, disengaging from the
collector hood tab, lift it clear of the locating peg
and remove.
INSTALLATION
11
DETERMINING THE FLUE LENGTH
11. Repeat steps 9 and 10 to remove the RH panel.
12. The boiler is held to the packaging base by 4 M6
hex head screws. Remove the front screws,
slacken the rear screws and remove the boiler from
the packaging base.
It is MOST IMPORTANT that the boiler is installed in a vertical position.
WARNING.
For top outlet installation the flue
terminal MUST always be in the
horizontal position (not available on
125 model).
Top outlet flue length
= A + B + Elbow allowance
o
Elbow = 1m
90
45o Elbow = 0.7m
FLUE KITS
Pack B: supplied as standard.
Pack D: optional extension kit for side
flue, top or rear flue outlet. Refer to 'Flue
Extension Ducts'
14
1. A maximum of 2 extension ducts (plus
the standard flue duct) may be used
together for 100 or 1 extension duct
for 125.
2. Flue extensions of greater than 1m
(39") should be supported with the
bracket provided.
Flue length
Up to 600 B, 1 off B, 1 off 150 308
600 to 1000 B, 1 off + D, 1 off B, 1 off + D, 1 off 150 308+152132
600 to 1550 B, 1 off + D, 1 off N/A 150 308+
1505 to 2000 B, 1 off + D, 2 off N/A 150 308+
mm
100 Pack Req. 125 Pack Req. Product No.
152132, 1 off
152132, 2 off
British Gas 100 & 125 RD2 - Installation & Servicing
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