Ideal Boilers BOXER C 24 User guide

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When replacing any part on this appliance, use only spare parts that you can be assured conform
to the safety and performance specification we require. Do not use reconditioned or copy parts
that have not been clearly authorised by the manufacturer.
installation and
servicing
C24 & C28
Combination boiler
Your installation and servicing guide

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2BOXER combination boiler - Installation and Servicing
GENERAL
Gas supply 2H - G20 - 20mbar / 3P - G31 - 37 mbar
Gas Supply Connection 22mm copper
Injector size G20 Natural Gas 1.2 mm (13 x) 1.2 mm (15 x)
Inlet Connection Domestic Hot Water 15mm copper
Outlet Connection Domestic Hot Water 15mm copper
Flow Connection Central Heating 22mm copper
Return Connection Central Heating 22mm copper
Flue Terminal Diameter mm (in) 100 (4)
Average flue temp/mass flow rate (DHW) 122.5oC / 14.6g/s 124.5oC / 18.1g/s
Maximum Working Pressure (Sealed Systems) bar (lb/in2) 3.0 (43.5)
Maximum Domestic Hot Water Inlet Pressure bar (lb/in2) 10.0 (145)
Minimum Domestic Hot Water Inlet Pressure bar (lb/in2) 0.5 (7)
Electrical Supply / Power consumption 230 V ~ 50 Hz. / 137 W
Fuse Rating External : 3A Internal : 4AF 250 V
Water content Central Heating litre (gal) 1.5 (.33) 1.6 (.35)
Domestic Hot Water 0.5 (0.11) 0.5 (0.11)
Packaged Weight kg (lb) 38 (84) 39 (86)
Maximum Installation Weight kg (lb) 36 ( 80) 37 (82)
Boiler Casing Size Height mm (in) 700 (27 5/8) 750 (29 1/2)
Width mm (in) 450 (17 3/4)
Depth mm (in) 285 (11 1/4)
Table 1 - General Data
Note. Gas consumption is calculated using a
calorific value of 37.8 MJ/m3(1038 Btu/ft3)
gross or 34 MJ/m3 (910 Btu/ft3) nett at 15°C
and 1013.25 mbar.
To 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)
b. For ft3/h - divide the gross heat input (Btu/
h) by the gross C.V. of the gas (Btu/ft3)
Key to symbols
I E = Ireland, GB = United Kingdom (Countries of destination)
PMS = Maximum operating pressure of water
C12 C32 C52 = A room sealed appliance designed for connection via ducts to a
horizontal or vertical 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.
II2H3P = An appliance designed for use on 2nd and 3rd Family gases.
* 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 a notified body.
CAUTION. To avoid the possibility of injury during the installation, servicing or cleaning
of this appliance, care should be taken when handling edges of sheet steel components.
Table 2 - Performance Data - Central Heating and Domestic Hot Water (D.H.W.)
Boiler Input : Max. Min. Max. Min.
Nett CV kW 26.5 12.5 31.0 14.5
(Btu/h) (90,400) (42,650) (105,800) (49,500)
Gross CV kW 29.4 13.9 34.4 16.1
(Btu/h) (100,300) (47,400) (117,300) (54,900)
Burner Pressure mbar 12.8 2.8 13.1 2.9
(G 20) (in.w.c.) ( 5 1/8) ( 1 1/8) ( 5 1/4) (1 1/8 )
Gas Consumption l/s 0.78 0.37 0.91 0.42
(ft3/h) (99.3) (47) (115.8) (53.5)
Boiler Output : kW 24.3 11.1 28 12.6
(Btu/h) (82,900) (37,800) (95,500) (43,000)
Flow Rates for ∆T 35°C l/min 10.0 11.5
Seasonal efficiency (SEDBUK)* D Band [79.1]% D Band [79.8]%
NOx Classification Class 3
BOXER C 24 BOXER C 28
BOXER C 24 BOXER C 28
Note. For 3rd Family gases, supply and burner pressure are given in the instructions sheet supplied with the Conversion kit.

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3BOXER combination boiler - Installation and Servicing
GENERAL
CONTENTS
page no.
Air Supply ....................................................................... 7
Boiler Clearances ......................................................... 6
Boiler Exploded Diagram ...................................... 10, 11
Electrical Connections ...............................................22
Electrical Supply ...........................................................8
Extension Ducts - Fitting ....................................... 17, 18
Fault Finding ....................................................... 45 to 49
Flow Wiring Diagram .................................................. 23
Flue Fitting
Rear outlet .............................................................. 13
Side outlet .............................................................. 13
Flue Installation ............................................................. 7
Gas Safety Regulations ................................................ 5
Gas Supply ..................................................................... 7
Installation ......................................................... 10 to 27
Mandatory Requirements ......................................5 to 9
Pump .......................................................................... 39
Servicing ............................................................ 28 to 44
Short List of Parts ....................................................... 50
Thermostatic Radiator valves ..................................... 8
Water and Systems ............................................ 8 to 10
Water Connections ............................................... 19, 20
Water Treatment ......................................................... 10
Wiring Diagrams ............................................... 21 to 23
BOXER
Natural Gas only
G.C. Appliance No. 47-348-22 ( BOXER C 24 )
G.C. Appliance No. 47-348-23 ( BOXER C 28 )
PI No. 0049AU2867 ( BOXER C 24 )
0049AU2949 ( BOXER C 28 )
Destination Countries: GB, IE
NOTE TO THE INSTALLER: LEAVE THESE
INSTRUCTIONS ADJACENT TO THE GAS METER.
ALSO COMPLETE THE BENCHMARK LOG BOOK
AND GIVE THIS TO THE CUSTOMER.
BENCHMARK LOG BOOK DETAILS
Boiler Page
Make and model ....................................................... 3
Appliance Serial No. on Data Badge
Controls ............................................... as applicable
For all boilers
Flushing to BS.7593 .............................................. 10
Inhibitor .................................................................. 10
Gas inlet working pressure ......................................7
Burner operating pressure....................................... 2
Heat input..........................................to be calculated
Temperature differential .......... measure and record
For combination boilers .......................................... 9
For domestic hot water mode ................................9
For all boilers: complete, sign & hand over to customer
For assistance see Technical Helpline on the back page

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4BOXER combination boiler - Installation and Servicing
GENERAL
1 BOILER WATER CIRCUIT DIAGRAMSINTRODUCTION
The BOXER combi boiler is a fully automatically controlled,
wall mounted, low water content, fanned flue combination gas
boiler.
Note.
Due to the high efficiency of the boiler a plume of water vapour
may form at the terminal during operation.
Central heating (CH) output is fully modulating with a range of:
11.1 to 24.3 kW (37,800 to 82,900 Btu/h) for BOXER C 24
12.6 to 28.0 kW (43,000 to 95,500 Btu/h) for BOXER C 28
Instantaneous Domestic hot water (DHW) output is also fully
modulating with a maximum of:
24.3 kW (82,900 Btu/h) for BOXER C 24
28 kW (95,500 Btu/h) for BOXER C 28
The boiler is supplied fully assembled with DHW built in heat
exchanger, diverter valve, circulating pump, pressure gauge,
safety valve and CH expansion vessel.
Variable CH and DHW temperature controls are fitted on the
user control.
The boiler casing is of white painted coated mild steel.
The boiler temperature controls are placed at the botton of the
front panel.
The heat exchanger is of finned oval copper tubes.
The boiler is suitable for connection to fully pumped, sealed
water systems ONLY.
The system pipework MUST include drain cocks in appropriate
places.
Pipework from the boiler is routed downwards as standard, but
may be routed upwards behind the boiler using the stand-off
frame (supplied in a separate kit).
OPERATION
With no demand for CH the boiler fires only when DHW is
drawn off.
When there is a demand for CH, the heating system is
supplied at the selected temperature of between 45oC and
82oC, until DHW is drawn off. The full output from the boiler is
then directed via the diverter valve back to the heat exchanger to
supply a maximum DHW draw-off at 35oC temperature rise of:
- 10.0 l/min for BOXER C 24
- 11.5 l/min for BOXER C 28
At low DHW draw-off rate the maximum temperature is limited
to 62 oC by the modulating gas control.
Refer also to Frame 1 - 'Boiler Water Circuit Diagrams'
Central Heating Circuit
Domestic Hot Water Circuit
Fan
Expansion
vessel
Diverter
valve
C.H.
Temperature
sensor
H.L.
Termostat
Air Pressure
Switch
Low
Pressure
switch
Heat
exchanger
Burner
Flame sensing
electrode Ignition
electrode
Pump
Automatic
air vent
Gas valve
Safety
relief valve
CH Flow
Gas
CH Return
Fan
Diverter
valve
Air Pressure
Switch
Heat
exchanger
Flame sensing
electrode
Ignition
electrode
Gas valve
Gas
H.L.
Termostat
Burner
Pump
Automatic
air vent
Safety
relief valve
Flow rate
switch
DHW Cold in
DHW Hot out
DHW
Temperature
sensor
Flow
restrictor
Cold water
filter
Low
Pressure
switch

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5BOXER combination boiler - Installation and Servicing
GENERAL
SAFETY
Current Gas Safety (installation and use) regulations or rules
in force:
It is law that all gas appliances are installed and serviced 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, bye-laws of the local water authority, the building
regulations and the Building Standards (Scotland) and any
relevant requirements of the local authority.
Detailed recommendations are contained in the following British
Standard Codes of Practice:
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. 5449 Forced circulation hot water systems.
BS. 5546 Installation of gas hot water supplies for
domestic purposes (2nd and 3rd Family Gases)
BS. 6798 Installation of gas fired hot water boilers of rated
input not exceeding 70 kW.
BS. 6891 Low pressure installation pipes.
Health & Safety Document No. 635.
The Electricity at Work Regulations, 1989.
The manufacturers notes must NOT be taken, in any way, as
overriding statutory obligations.
IMPORTANT. These appliances are CE certificated for safety
and performance. It is, therefore, important 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 as otherwise
recommended by Caradon Ideal Limited in writing. If in doubt
please enquire.
Any direct connection of a control device not approved by
Caradon Ideal Limited could invalidate the certification and the
normal appliance warranty. It could also infringe the Gas Safety
Regulations and the above regulations.
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 CFCs are included in any part of the boiler or its
manufacture.
LOCATION OF BOILER AND FLUE OUTLET
The boiler must be installed on a flat and vertical wall, capable
of adequately supporting the weight of the boiler and any
ancillary equipment.
The boiler may be fitted on a combustible wall and insulation
between the wall and the boiler is not necessary, unless
required by the local authority.
For electrical safety reasons there must be no access available
from the back of the boiler.
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 Engineering
document IGE/UP/7:1998.
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 should be designed
and constructed specially for this purpose.
An existing cupboard or compartment may be used, provided
that it is modified for the purpose.
In both cases, details of essential features of cupboard /
compartment design, including airing cupboard installation, are
to conform to the following:
lBS 6798 (No cupboard ventilation is required - see air supply
for details).
lThe position selected for installation MUST allow adequate
space for servicing in front of the boiler.
lFor the minimum clearances required for safety and
subsequent service, see the wall mounting template and
Frame 2. In addition, sufficient space may be required to
allow lifting access to the wall mounting plate.
Bathroom Installations
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.
Note. It is not permissible to install a mains socket in a bathroom.
Where installation will be in an unusual location, special
procedures may be necessary and BS 6798 gives detailed
guidance on this aspect.
OPTIONAL EXTRA KITS
lFlue Extension Duct 1 m Pack D up to 3 m (122 in).
lFlue extension ducts 250 mm lengthPack D1
l90oElbow (maximum 2 per installation).
l45oElbow (maximum 2 per installation).
lRoof Flue Kit (to a maximum of 4.2 m)
lInclined roof tile
lFlat roof tile
lVertical flue connection
lBoiler Stand-off Kit
lConversion kit to change from 2nd family gasses to 3rd
family
lConversion kit to change from 3rd family gasses to 2nd
family
lDHW mini expansion vessel
lTwin pipe flue system
lPre Piping kit
Note: For Twin pipe system refer to your supplier

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6BOXER combination boiler - Installation and Servicing
GENERAL
2 BOILER DIMENSIONS, SERVICES & CLEARANCES all dimensions in mm (in)
The following minimum clearances must be maintained for
operation and servicing.
Additional space will be required for installation, depending
upon site conditions.
Side and Rear Flue
aProvided that the flue hole is cut accurately, e.g. with a core
drill, the flue can be installed from inside the building where
wall thicknesses do not exceed 600 mm (24"). Where the
space into which the boiler is going to be installed is less
than the length of flue required the flue must be fitted from
the outside.
Installation from inside ONLY
b. If a core boring tool is to be used inside the building the
space in which the boiler is to be installed must be at least
wide enough to accommodate the tool.
Front clearance
The minimum front clearance when built in to a cupboard is
5 mm (1/4") from the cupboard door but 480 mm (18 7/8")
overall clearance is still required, with the cupboard door
open, to allow for servicing.
* Bottom clearance
Bottom clearance after installation can be reduced to 5 mm.
However, 150 mm must be available for servicing.
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450 (17 3/4)
285 (11 1/4)
480 (18 7/8)
150 (6)
700 (27 5/8) BOXER C 24 750 (29 1/2) BOXER C 28
See inset (A) above
BOILER DIMENSIONS
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(3/4)
(3 5/32) (3 5/8)

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7BOXER combination boiler - Installation and Servicing
GENERAL
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 K6. In case of difficulty seek
advice from:
Grasslin (UK) Ltd.,
Vale Rise, Tonbridge, Kent TN9 1TB
Telephone No. 01732 359 888
Ensure that the guard is fitted centrally.
5. Where the terminal is fitted within 850mm (34") of a plastic
or painted gutter or 450mm (18") of painted eaves then an
aluminium shield at least 750mm (30") long should be
fitted to the underside of the gutter or painted surface fitted
centrally above the flue.
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: Part 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 as 'unsafe' until corrective action can be taken.
TERMINAL
The terminal assembly can be adapted to accommodate
various wall thicknesses. Refer to Frame 9 - Unpacking.
AIR SUPPLY
Detailed recommendations for all supply are given in BS5440.2
The following notes are for general guidance:
1. It is NOT necessary to have a purpose-povided 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/comparment, at both high and low levels.
The air vents must either comunicate with room/internal space,
or be direct to outside air. The minimum efective 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.
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 MUST be installed on a gas supply with a governed
meter only.
A gas meter can only be connected by the local gas supplier or
by a registered CORGI engineer.
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 working gas pressure of
20 mbar should be available at the boiler inlet.
Do not use pipes of a smaller size than the boiler inlet gas
connection.
IMPORTANT.
Installation pipes MUST be fitted in accordance with BS. 6891.
Pipework from the meter to the boiler MUST be 22mm O.D.
The complete installation MUST be tested for gas soundness and
purged as described in the above code.
FLUE INSTALLATION
Pluming may occur at the terminal, so where possible, terminal
positions where this could cause a nuisance should be
avoided.
The flue must be installed in accordance with the
recommendations of BS. 5440: Part 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 spacing from the terminal to
obstructions and ventilation openings are specified in
Table 3.
Table 3 - Balanced flue terminal position
Terminal Position Minimum Spacing
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 150 mm ( 6")
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")
Table 4
Boxer
C 24
C 28
Air from room/internal space
cm (in )
22
Air direct from outside
265 (41)
310 (48)
133 (21)
155 (24)
cm (in )
22

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8BOXER combination boiler - Installation and Servicing
GENERAL
Notes
a. 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.
b. Antifreeze fluid, corrosion and scale inhibitor fluids
suitable for use with boilers having copper heat
exchangers may be used in the central heating system.
Advice should be sought from a local water treatment
company.
THERMOSTATIC RADIATOR VALVES (TRV)
It is 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 area having a heating
requirement of at least 0.9kW (3000Btu/h) of the boiler heat
output should be achieved using a room thermostat whilst
other rooms are individually controlled by thermostatic radiator
valves. A higher proportion of TRVs may be used, provided that
a bypass between the boiler flow and return is fitted, to ensure
adequate flow when all TRVs are closed.
For further information refer to the 'Good Practice Guide 143', a
publication of the Energy Efficiency Office, available from the
Building Research Establishment, Garston, Watford WD2 7JR.
Tel: [phone].
ELECTRICAL SUPPLY
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 point of connection to the mains should be readily
accessible and adjacent to the boiler.
3 SYSTEM REQUIREMENTS - Central Heating
Safety valve setting bar 3.0
Vessel charge pressure bar 0.75 to 1
System pre-charge pressure bar 1.0
System volume Expansion vessel
(litres) volume (litres)
25 1.8
50 3.7
75 5.5
100 7.4
125 9.2
150 11.0
175 11.9
190 14.0
200 14.7
250 18.4
300 22.1
For other system volumes
multiply by the factor across 0.074
WATER CIRCULATION SYSTEM
The boilers are designed for connection to pressurised, fully
pumped, sealed water central heating systems ONLY. The
domestic hot water (DHW) calorifier is incorporated within the
heat exchanger and only requires connection to the mains
water supply.
IMPORTANT
Ensure that the mains water supply pressure is
adequate to provide the required DHW flow rate. Refer to
Table 2 on page 2.
The central heating system should be installed and
commissioned in accordance with BS. 6798 and, in addition,
for smallbore and microbore systems BS. 5449.
The domestic hot water system should be in accordance with
BS. 5546 and BS. 6700.
Copper tubing to BS 2871:1 is recommended for water
carrying pipework and MUST be used for pipework carrying
potable water.
Any soldered joints on potable water pipework MUST NOT be
made with solder containing lead.
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 or ventilated underfloor spaces.
Draining taps MUST be located in accessable positions, which
permit the draining of the whole system.
They should be at least 1/2" BSP nominal size and be
in accordance with BS 2879.
Maximum recommended system hydraulic losses are given in
the Table within Frame 4.
WATER TREATMENT - See frame 6

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9BOXER combination boiler - Installation and Servicing
GENERAL
4 SYSTEM REQUIREMENTS - CH (continued) and HOT WATER
General
1. The installation must comply with all relevant national and
local regulations.
2. The installation should be designed to work with flow
temperatures of up to 82 oC.
3. All components of the system must be suitable for a working
pressure of 3 bar and temperature of 110 oC. Extra care
should be taken in making all connections so that the risk of
leakage is minimised.
The following components are incorporated within the
appliance:
a. Circulating pump.
b. Safety valve, with a non-adjustable preset lift pressure of
3 bar.
c. Pressure gauge, covering a range of 0 to 4 bar.
d. A 5-litre expansion vessel for BOXER C 24 and a 8-litre
expansion vessel for BOXER C 28, with an initial charge
pressure of 1 bar.
4. 'Make-up' Water. Provision must be made for replacing
water loss from the system, either :
a. From a manually filled 'make-up' vessel with a readily
visible water level. The vessel should be mounted at
least 150 mm above the highest point of the system and
be connected through a non-return valve to the system,
fitted at least 150 mm below the 'make-up' vessel on the
return side of the radiators.
or
b. Where access to a 'make-up' vessel would be difficult, by
pre-pressurisation of the system.
The maximum cold water capacity of the system
should not exceed 67 litres for BOXER C 24 and 108
litres for BOXER C 28, if not pressurized. However,
with the system pressurized, the efficiency of the
expansion vessel will be reduced and a larger vessel
(or smaller system volume) may be necessary. If the
capacity of the vessel is not considered sufficient for
this, or for any other reason, an additional vessel
MUST be installed on the return to the boiler.
Guidance on vessel sizing is given in frame 3.
5. Filling. The system may be filled as follows:
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 must be used to facilitate
filling.
i. Thoroughly flush out the whole system with
cold water.
ii. Fill and vent the system until the pressure gauge
registers 1.5 bar, and examine for leaks.
iii. Check the operation of the safety valve by raising the
water pressure until the valve lifts.
This should occur within 0.3 bar of the preset lift
pressure.
iv. Release water from the system until the minimum
system design pressure is reached;
1.0 bar if the system is to be pre-pressurised.
When installing the filling connection provided with the
boiler, an additional WRAS approved value MUST be
fitted to the mains water supply, up stream of the
double check valve to fully comply with the water
regulations
Water Flow Rate and Pressure Loss
BOXER C 24 C 28
Max CH Output kW 24.3 28.0
(Btu/h) (82,900) (95,500)
Water flow rate l/sec 0.38 0.44
(gal/min) 4.9 5.7
Temperature Differential oC15 15
(oF) (27) (27)
Head available for m w.g. 2.3 2.3
system pump. (ft w.g.) 7.5 7.5
DOMESTIC HOT WATER
Domestic Hot Water Requirements
1. The domestic hot water service must be in accordance
with BS 5546 and BS 6700.
2. Refer to Table 1 for minimum and maximum working
pressures.
3. The boilers are suitable for connection to most types of
washing machine and dishwasher appliances.
4. When connecting to suitable showers, ensure that:
a. The cold inlet to the boiler is fitted with an approved
anti-vacuum or syphon non-return valve.
b. Hot and cold water supplies to the shower are of equal
pressure.
5. Hard Water Areas
Where the water hardness exceeds 200 mg/litre, it is
recommended that a proprietary scale reducing device
is fitted into the boiler cold supply within the
requirements of the local water company.
IMPORTANT
Provision MUST be made to accommodate the expansion of
DHW contained within the appliance, if a non-return valve is
fitted to the DHW inlet.
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Supplied By www.heating spares.co Tel. [phone]
10 BOXER combination boiler - Installation and Servicing
INSTALLATION
The boiler does not normally need a bypass but at least some
radiators on the heating circuit, of load of at least 20% of the
minimum boiler output, must be provided with twin lockshield
valves so that this minimum heating load is always available.
See note regarding thermostatic radiator valves on page 8.
Note.
Systems incorporating zone valves which could completely cut
off the flow through the system, must be wired such that the
boiler will not fire or continue to fire when this occurs.
BALANCING
1. Set the programmer to ON.
Close the manual or thermostatic valves on all radiators,
5 SYSTEM BALANCING
leaving the twin lockshield valves (on the radiators referred
to above) in the OPEN position.
Turn up the room thermostat and adjust these lockshield
valves to give boiler flow and return temperatures not more
than 20 oC apart.
These valves should now be left as set.
2. Open all manual or thermostatic radiator valves and adjust
the lockshield valves on the remaining radiators, to give
around 15 oC temperature drop at each radiator.
3. Adjust the room thermostat and programmer to NORMAL
settings.
6 WATER TREATMENT
The BOXER boiler has a COPPER heat exchanger
IMPORTANT.
The application of any other treatment to this product may render the guarantee invalid.
If water treatment is used, FERNOX MB1 or SENTINEL X100 is recommended. For further information, to contact:
Fernox Manufacturing Co. Ltd.
Betz Dearborn Ltd., Widnes, Cheshire, WA8 8UD
Tel: [phone]
Tandem House, Marlowe Way, Croydon, Surrey, CRO 4XS.
Tel: [phone]
Sentinel Division
Notes.
1. It is most important that the correct concentration of the
water treatment product is maintained in accordance with
the manufacturers' instructions.
2. If the boiler is installed in an existing system any
unsuitable additives MUST be removed by thorough
cleansing. BS. 7593:1992 details the steps necessary to
clean a domestic central heating system.
3. In hard water areas, treatment to prevent lime scale
may be necessary - however, the use of artificially
softened water is NOT permitted.
4. Under no circumstances should the boiler be fired
before the system has been thoroughly flushed.
19. CH flow pipe.
20. CH thermistor.
21. Diverter valve.
22. By-pass pipe.
23. DHW outlet fitting.
24. DHW outlet pipe.
25. DHW inlet pipe.
26. Overheat thermostat.
27. Low water switch.
28. DHW thermistor.
29. Heat exchanger.
30. Air pressure switch.
31. Venturi.
32. Fan outlet gasket.
33. Fan.
34. Fan bracket.
35. Fan inlet gasket.
36. Collector hood.
1. Complete casing.
2. LH ignition lead.
3. Gas valve.
4. Gas inlet pipe.
5. Ignition/Flame detection electrode.
6. Burner.
7. Ignition transformer.
8. Pump.
9. Pressure gauge.
10. Fascia board.
11. Control Housing.
12. Automatic air vent.
13. CH return pipe.
14. DHW Inlet fitting.
15. Pump clips.
16. Pressure relief valve.
17. DHW flow switch.
18. DHW inlet pipe.
7 BOILER ASSEMBLY - Exploded View Legend
37. Exp. vessel flexible pipe.
38. Fixing clips.
39. Expansion vessel.
40. Combustion chamber insulation.
41. Combustion chamber.
42. Mains chassis.
43. Flow restrictor.
44. Vertical protection shield.
45. Horizontal protection shield.
46. Flame detection lead.
47. Overheat thermostat clamp.
48. PCB.
49. Fan outlet connector.
96. RH ignition lead.
INSTALLATION

Supplied By www.heating spares.co Tel. [phone]
11BOXER combination boiler - Installation and Servicing
INSTALLATION
8 BOILER ASSEMBLY - Exploded View
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INSTALLATION

Supplied By www.heating spares.co Tel. [phone]
12 BOXER combination boiler - Installation and Servicing
INSTALLATION
9 UNPACKING
The boiler is supplied fully assembled in one Pack A, together
with a standard flue assembly for lengths up to 720 mm, rear
or side flue outlet, in Pack B.
Optional extras, if ordered, are available in separate boxes.
Unpack and check the contents.
Hardware Pack
lWall plugs with hook screw - 2 off.
lWall mounting template - 1 off.
lCH Flow and Return isolating valve
- 2 off.
lCW inlet isolating valve - 1 off.
lHW outlet pipe - 1 off.
lGas isolating valve - 1 off.
l3/4 gaskets - 3 off.
l1/2 gaskets - 2 off.
lSmoke outlet diaphragm - 1 off.
lInstructions for mounting flue
restrictor
Pack A Contents
Also contained in Pack A:
lHardware Pack (listed below).
lThese Installation & Servicing Instructions.
lThe User's Instructions.
lBenchmark book.
1. Ensure the boiler is positioned correctly as marked
on the carton (reverse position).
2. Remove the band and staples.
3. Fold back the top flaps and the plastic bag to get
access to the boiler.
4. Reverse the carton on the side where top flap has
been folded to 270° (The other top flaps can be
folded to 180° only).
5. Lift the card board box.
6. Dispose of packaging.
7. Remove the plastic bag and collect instructions and
read them thoroughly before installing the boiler.
10 PACKAGING REMOVAL
Pack B Contents
1- Flue turret.
2- Flue terminal.
3- External rubber ring.
4- Internal rubber ring.
5- Gasket for turret flange.
6- Gasket for inner pipe - 2 off.
7- Self tapping screws - 4 off.
8- Sleeve with clamp for ext. pipe - 1 off.
Instructions.
1
2
3
Complete boiler
Piping kit
Wall mounting template
Flue restrictor
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INSTALLATION

Supplied By www.heating spares.co Tel. [phone]
13BOXER combination boiler - Installation and Servicing
INSTALLATION
FLUE KITS
Pack B - supplied as standard
Pack D - optional extension kit for side flue
or rear flue outlet.
Refer to 'Flue Extension Ducts'
11 CASING REMOVAL
IMPORTANT. The boiler MUST be installed
in a vertical position
Dimension X - Wall thickness.
Dimension L - Wall thickness plus boiler spacing.
Dimension S - Upward routing pipework frame depth = 50 mm
1. Undo the upper front retaining screw (A).
2. Undo the LH and RH side nuts retaining the plastic
fascia board (B) and remove.
3. Release the four fixing clamps on the upper and lower
positions (2 + 2) (C).
4. Lift and remove casing (D).
5. Place to one side the removed casing to avoid damage.
12 DETERMINING THE FLUE LENGTH AND FLUE PACKS REQUIRED
Notes.
1. The flue duct MUST be inclined at 1.5 degrees to the
horizontal to not allow the rain come into the boiler.
2. If the boiler is to be installed with upward piping routed
behind the boiler then the optional stand-off kit should be
used. Care must be taken when cutting the ducts and
marking wall to suit this condition.
3. If no extenction ducts are required, the flue restrictor must
be fitted.
Note.
For flue options refer
to page 5.
Total Flue length dimension Flue
Rear flue Side flue Extra packs
dim. X+185 dim. L+225 required
Up to 720 Up to 720 none
Up to 1685 Up to 1685 Pack D 1 - off
Up to 2650 Up to 2650 Pack D 2 - off
185 + S = 235 mm
185 mm
Rear flue length X
225 mm 225 mm
Side flue length L
See also frame 16 and 17
A
B
C
C
D
D
INSTALLATION

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14 BOXER combination boiler - Installation and Servicing
INSTALLATION
FLUE OUTLET
Notes.
Cut the template in two separated parts (A) and (B):
a. If rear flue is used, only part (A) off template is necessary.
b. If side flue is used, also part (B) off template is necessary;
then follow the instructions given on it.
c. The template shows the positions of the fixing holes and
the flue hole centres for standard installation and for using
the stand-off. Care must be taken to ensure the correct
holes are drilled.
1. Tape template into the selected position.
2. Ensure squareness by hanging a plumbline as shown. If
fitting a side flue, extend the flue centre line onto the side
wall.
3. Mark onto the wall the following:
a. If the boiler will be placed directly to the wall (without
stand-off kit): the fixing holes with center to center
distance of 135 mm (5 5/16).
b. If the boiler will be placed on the wall by using the
stand-off kit: the fixing holes with center to center
distance of 392 mm (15 7/16).
c. The position of the flue duct hole.
Note. Mark the centre of the hole as well as the
circumference
4. Remove the template from the wall.
14 WALL MOUNTING TEMPLATE
13 FLUE ASSEMBLY - Exploded View
1. An optional flue duct extension kit is required
for wall thicknesses greater than :
Side 580 mm (23 5/8").
Rear 620 mm (24 3/8") - w/o stand-off kit.
570 mm (22 3/8") - with stand-off kit.
Rear flue arrangement shown
Note.
Side flue only. If the system pipework is to be routed
up behind the boiler, the upward routing pipework
frame supplied as a separate kit MUST be used
secured to the piping frame. It is essential to use the
wall mounting template to mark the holes to be
drilled. Care MUST be taken to ensure the correct
holes are drilled.
LEGEND
1- Flue turret.
2- Flue terminal.
3- External rubber ring.
4- Internal rubber ring.
5- Gasket for turret flange.
6- Gasket for inner pipe - 2 off.
7- Self tapping screws - 4 off.
8- Sleeve with clamp for ext. pipe - 1 off.
Instructions.
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15BOXER combination boiler - Installation and Servicing
INSTALLATION
FLUE OUTLET
15 PREPARING THE WALL
WARNING. Ensure that, during the cutting operation,
masonry falling outside of the building does not
cause damage or personal injury.
1. Cut the flue hole (preferably with a 5" core boring
tool), ensuring that the hole is square to the wall.
Both wall faces immediately around the cut hole
should be flat.
2. Drill 2 holes (see frame 14) with a 12 mm (1/2")
masonry drill and insert the plastic plugs
complete with hook screws, provided, for the
upper boiler bracket.
or
Drill 4 holes (see frame 14) with a 12 mm (1/2")
masonry drill for the stand-off kit.
16 CUTTING THE FLUE - REAR Wall thicknesses of 114 to 620 mm
Note.
a. If using the extension ducts go to Frame 20.
b. If the upward routing pipe stand-off kit is used it is
essential add 50 mm to 'X' the measured wall
thickness when marking the flue (this will allow for the
fitted stand-off kit).
1. Measure and note wall thickness X - Refer to Frame 12
2. Add 90 mm (3 9/16) to dimension X and, measuring
from the groove, cut the outer tube only.
3. To ensure the tube is cut square, mark the flue all the
way round.
4. Cut the inner tube to a length 20 mm (3/4") longer to
aid engagement.
17 CUTTING THE FLUE - SIDE Wall thicknesses of 114 to 580 mm
Note.
If using the extension ducts go to Frame 20.
1. Measure and note wall thickness X - Refer to Frame 12
2. Add 130 mm (5 1/8") to dimension X and, measuring
from the groove, cut the outer tube only.
3. To ensure the tube is cut square, mark the flue all the
way round.
4. Cut the inner tube to a length 20 mm (3/4") longer to
aid engagement.
Note. If the terminal is to be sited within 25-40 mm of a corner or vertical
pipe then the hole MUST be accurately cut.
Rear flue
only 5
diameter
hole
Side flue
only 5
diameter
hole
Note: Check all of the hole
positions before drilling.
Section
through
wall
X
With stand-off kit
Without stand-off kit
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16 BOXER combination boiler - Installation and Servicing
INSTALLATION
FLUE OUTLET
18 MOUNTING THE BOILER
Note. All the isolating valves are supplied separately in the
hardware pack.
Fit the boiler either:
a. Directly to the wall
1. Ensure that the plastic plugs are removed from both
the DHW and CH pipes before mounting;
Note. Some spillage of water may occur from the
pipework when mounting the boiler to the installation.
2. Lift the boiler onto the wall, locating the slots of its
upper bracket to the hooks already fitted;
3. Lower the boiler into position;
4. Using the correctly sized fibre washers supplied in the
hardware pack, engage and then tighten the 4 water
unions;
5. Engage and tighten the gas union, ensuring that the
fibre seal is in place;
6. Connect a pipe to the safety drain outlet using a
pressure fitting 15 mm O. dia.;
Service connections may be made now, before
mounting the boiler. If required refer to Frames 24 to 27.
or
b. Use stand-off kit
(To allow pipework to be taken upwards).
1. Assemble the 4 plastic plugs and the screws on the
stand-off frame as indicated;
2. Fit the stand-off frame on the wall;
3. Hang the boiler onto the stand-off frame;
4. Using the correctly sized fibre gaskets supplied in
the hardware pack, engage and then tighten the 4
water unions;
5. Engage and tighten the gas union, ensuring that the
fibre seal is in place;
6. Connect a pipe to the safety drain outlet using a
pressure fitting 15 mm O. dia. ;
Note.
If the clearances above and below the boiler are less
than the length of the pipes it will be necessary to
position the pipes behind the wall mounting plate
BEFORE the plate is screwed to the wall.
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FLUE OUTLET

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17BOXER combination boiler - Installation and Servicing
INSTALLATION
FLUE OUTLET
19 CONNECTING THE FLUE TO THE BOILER
1. Insert the flue assembly through the prepared hole in the
wall.
2. Fit the flue turret on the top of the boiler ensuring that the
seal is in place, and that the flue outlet seal at A is correctly
located.
3. Locate the flue into the turret.
4. Secure the flue turret on top of the boiler by inserting the 4
screws provided.
$
5. Flues over 0.72 metre long.
Fix the flue support bracket to the wall, using the wall plug
and wood screw. For standard installations use the short
wood screw.
If the stand-off option is used, secure the support bracket
using the spacer bracket and long wood screw.
Note. When no extension duct is used, the flue restrictor
supplied in hardware pack A, must be fitted.
Flue restrictor
20 FLUE EXTENSION DUCTS - For flue lengths greater than 720 mm
Pack D Flue extension duct kit contents.
1. A maximum of 3 extension ducts (one suitably
cut) plus the standard flue duct may be used
together.
2. Flue extensions of greater length than 1m (39")
should be supported with the bracket provided,
suitably adjusted - refer to Frame 20.
21 FLUE EXTENSION DUCTS - continued
Note. Side flue shown
The maximum total flue length is 3 m
General arrangement
Flue duct support
with wall plugs.
Extension duct and clamp
965 mm (38)
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FLUE OUTLET

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18 BOXER combination boiler - Installation and Servicing
INSTALLATION
FLUE OUTLET
1. Fit the inner flue extension duct onto the inner flue duct.
2. Fit the outer flue extension duct onto the outer air duct.
3. Using the clamp provided clamp the flue lengths together.
4. Repeat steps 1-3 if a second flue extension is required.
5. Measure and mark the flue length required onto the flue,
measuring from the groove near the terminal.
6. To ensure a square cut, mark the flue all the way round.
7. Cut to length at the right size the external duct and cut the
internal one 20 mm longer.
8. De-burr the metal edges.
22 FITTING THE KIT
General Notes
1. Fitting the Piping Frame, top entry pipework is an option, as
well as mounting from the bottom or through the wall.
If pipes are run vertically within the boiler back space
provided by optional stand-off frame positions they must
avoid any obstructions imposed by the channels and by a
rear facing flue, should this position be selected.
23 SERVICE CONNECTIONS
2. Horizontal connecting pipes, where used, must be run
outside the limits of the boiler casing.
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FLUE OUTLET

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19BOXER combination boiler - Installation and Servicing
INSTALLATION
FLUE OUTLET
24 WATER CONNECTIONS
CH CONNECTIONS
Refer to General Note, Frame 23, for guidance.
Note. Do not subject any of the isolating valves to heat as the
seals may be damaged.
25 WATER CONNECTIONS - continued
DHW CONNECTIONS
Note. The flow regulator and the filter are
mounted internal of the boiler.
It should be inspected to ensure no
blockage is evident.
See frame 65
Isolating valve
(shown in the
open position)
22 mm copper pipe
22 mm copper pipe
Isolating valve
(shown in the
open position)
C.H. FLOW
C.H. RETURN
15 mm copper pipe
D.H.W.
OUTLET
D.C.W.
INLET
Isolating valve
(shown in the
open position)
Filter
15 mm copper pipe
Restrictor
Flow switch

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20 BOXER combination boiler - Installation and Servicing
INSTALLATION
The safety valve is located at the bottom RHS of the boiler.
The discharge pipe should be positioned so that the discharge of water or steam cannot create a hazard to the occupants of
the premises or damage the electrical components and wiring.
27 SAFETY VALVE DRAIN
1. Extend a gas supply pipe of not less than 15 mm O.D.
copper to the boiler.
A working gas pressure of 20 mbar (8" w.g) should be
available at the boiler inlet, with the boiler firing at full DHW
output.
26 GAS CONNECTION
28 FILLING
Central Heating
1. Remove the boiler casing Refer to Frame 11.
2. Ensure that the CH isolating valves are open.
3. Fill and vent the system. Check for water soundness.
IMPORTANT - when filling:
a. The cap on the automatic air vent (refer to Frame 64)
MUST be loose at all times.
When filling, there may be a slight water leak from the vent
therefore electrical connections should be protected.
b. Bleed any air from the pump and ensure that it is free to
rotate.
i. Remove the vent plug
ii. Using a screwdriver, rotate the shaft several times
iii. Replace the vent plug.
Note. Some slight water leakage will occur.
Domestic Hot Water
1. Fully open all DHW taps and ensure that water flows freely
from them.
2. Close all taps except the one furthest from the boiler.
3. Turn off the DHW tap. Note. The domestic hot water flow rate is automatically
regulated to a maximum of 12 l/min (2.6 gpm) for BOXER C 28
and 10 l/min (2.2 gpm) for BOXER C 24.
Gas cock
(shown in the
open position)
GAS IN
1
Automatic
air vent
Cap
Pump
Rotate the
shaft to free
Vent plug
a
b
INSTALLATION