157290-3.pmd

Concord CXA/H

- Installation and Servicing

GENERAL

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.

Boiler

CXA 40/H CXA 50/H CXA 60/H CXA 70/H CXA 80/H CXA 90/H CXA 100/H CXA110/H CXA120/H

Number of sections

Flow tappings

Rc (in. BSP)

2 x 2 at rear

Return tappings

Rc (in. BSP)

2 x 2 at rear

Maximum static head metres (feet)

61 (200)

Maximum pressure

bar (p.s.i.)

6.0 (87)

Gas inlet connection Rc (in. BSP)

3/4 (3/4)

1 (1 )

Minimum dynamic

mbar gauge

15.0

16.5

15.0

16.5

15.5

16.5

17.0

17.5

gas pressure required
at the boiler inlet

(in.w.g.)

(6.0)

(6.6)

(6.0)

(6.6)

(6.2)

(6.6)

(6.8)

(7.0)

Electricity supply

230 Volts- single phase, 50 Hz, fuse 5 A

Nominal flue size (to BS. 835) m m

150

175

200

250

(in.)

(6)

(7)

(8)

(10)

Diverter outlet socket

m m

184

213

238

288

internal diameter

(in.)

(7.3)

(8.4)

(9.4)

(11.3)

Length of burner bars (overall) m m

377

497

617

737

857

(in)

(14.8)

(19.5)

(24.3)

(29.0)

(33.7)

Main burner injectors( 3 off) size, mm

3.4

3.82

4.12

4.57

4.86

5.2

5.3

5.5

Approximate dry weight

210

265

330

395

490

(lb.)

(463)

(584)

(727)

(871)

(1078)

Water content

litre

(gal.)

(4.8)

(6.6)

(8.2)

(9.9)

(11.7)

Table 2 - General Data

* This value is in the UK government's Standard Assessment Procedure (SAP) for energy rating of dwellings.
The test data from which it has been calculated has been certified by Advantica 0087.

Boiler

CXA 40/H CXA 50/H CXA 60/H CXA 70/H CXA 80/H CXA 90/H CXA 100/H CXA 110/H CXA 120/H

Number of Sections

Boiler Input

Gross

48.3

60.3

72.4

84.5

96.5

108.6

120.7

132.7

144.8

Btu/hr x 1000 164.7

205.8

247.0

288.2

329.3

370.5

411.7

452.8

494.0

Nett

43.5

54.3

65.2

76.1

87.0

97.8

108.7

119.6

130.4

Btu/hr x 1000 148.3

185.4

222.5

259.6

296.7

333.8

370.9

408.0

445.0

Boiler Output

100

110

120

Btu/hr x 1000 136.5

170.6

204.7

238.8

273.0

307.1

341.2

375.3

409.4

Gas rate

4.60

5.75

6.90

8.05

9.20

10.35

11.50

12.64

13.79

/h 162.4

203.0

243.6

284.2

324.8

365.4

406.0

446.6

487.1

Approx. flue

4.5% CO

&100°C.m

0.04

0.05

0.06

0.07

0.08

0.09

0.10

0.11

0.12

gas volume

4.5% CO

& 212°F. ft.

106

127

148

170

191

212

233

254

Manifold setting pressure

mbar

9.7

9.8

10.2

10.0

9.3

9.6

10.7

11.1

12.1

in.w.g.

3.9

4.1

4.0

3.7

3.8

4.3

4.4

4.8

Part load efficiency (Gross)

83.5

83.6

83.4

82.4

82.6

83.8

81.9

83.7

85.1

Seasonal efficiency (SEDBUK)*

[79.9]% [79.9]% [79.9]% [79.9]% [79.9]% [79.9]% [79.9]% [79.9]% [79.9]%

Table 1- Performance Data

Note. To obtain gas consumption in l/s, divide gross heat input in (kW) by a calorific value of 37.8 (MJ/m

157290-3.pmd

11/7/2005, 11:09 AM

Concord CXA/H -

Installation and Servicing

CONTENTS

Air Supply. ........................................................................ 8

Boiler Assembly - exploded view. ................................... 9

Boiler Clearances. ........................................................... 5

Burner Assemblies - exploded views.

CXA 40/H-80/H ........................................................... 22
CXA 90/H-120/H ......................................................... 22

Casing Assembly. ........................................................... 19

Chimney System. .............................................................. 8

Commissioning & Testing. ............................................. 17

Electrical Connections. .................................................. 13

Electrical Supply. .............................................................. 8

Fault Finding. ................................................................... 28

Gas Safety Regulations .................................................... 3

Gas Supply. ........................................................................ 8

Hydraulic Resistance. ...................................................... 5

Initial Lighting. ................................................................. 17

Installation. ........................................................................ 9

Mandatory Requirements. ............................................... 7

Option Kits. ........................................................................ 4

Pump. ................................................................................ 6

Servicing. ........................................................................ 19

Short List of Parts. ......................................................... 30

Site Assembled Boilers. ................................................. 26

Static Head Requirements. .............................................. 6

System Connections. ..................................................... 11

Ventilation. ........................................................................ 8

Water Circulation. ............................................................ 4

Water Connections. ......................................................... 4

Water Treatment. ............................................................. 6

Wiring Diagrams. ............................................................ 14

Concord CXA 40/H-120/H (Natural gas)

B.G. Certified - P.I. No. 87/AP/80

Destination Countries: GB and IE

INTRODUCTION
CONSTRUCTION

BOILER BODY

The sectional boiler body is of cast iron and is supplied
assembled on a sheet steel combustion chamber with an integral
draught diverter. The boiler can be supplied in sectioned form to
special order for site assembly - refer to the section headed
`Instructions for Site Assembled Boilers'.

CASING

The casing is manufactured in stove enamelled sheet steel
and is easily assembled on site.

BURNERS

The 3 burners are of stainless steel construction.

Gas Safety (Installation and Use) Regulations or rules
in force.

It is the 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
that the law is complied with.

The Concord CXA 40/H-120/H range of boilers has been tested
and certified by British Gas to prEN656 for use with Natural gas
only.

Multiple boiler installations

The Concord CXA/H range is certificated for use in multiple
boiler installations, providing that the following conditions are
satisfied.

1. A downdraught thermostat kit MUST be fitted to ALL boilers

in the installation.

2. A maximum of 6 boilers may be used with a single flue

header.

3. For clearances see Frame 2.

A comprehensive guide to multiple installations of Concord
CXA/H boilers is available.
WARNING.
Failure to use a downdraught kit on every boiler in a multiple
boiler installation will negate the certification of the installation
and therefore contravene the essential requirements of the Gas
Appliance Directive.

Note. Concord CXA 40/H, CXA 50/H and CXA 60/H boilers are
intended for use as COMMERCIAL BOILERS and are NOT
certified for use in domestic applications. A domestic installation
is defined as an installation where the boiler takes its combustion
air from a living space or from a room directly or indirectly
connected with the living space. It is important, therefore, that no
external control devices - e.g. flue dampers, economisers etc.,
are directly connected to this appliance unless covered by these
Installation and Servicing Instructions or 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 British Gas Certification, the
normal appliance warranty and could also infringe the Gas Safety
Regulations. Table 1, Table 2 and the descriptive notes which
follow contain all the essential data likely to be required by the
installer.

157290-3.pmd

11/7/2005, 11:09 AM

Concord CXA/H

- Installation and Servicing

GENERAL

Boiler Size

Cold Feed

Open Vent

CXA 40/H - 50/H

3/4

CXA 60/H -120/H

1/4

Sealed system filling point - refer to Frame 8

Flow and return connections are 2" BSP.
A 1" BSP tapping is provided in the redundant return flange for
the cold feed or expansion vessel connection.
Safety Valve
A safety valve must be sized and fitted in accordance with BS.
6644 for every type of system. The valve should be set at 0.7
bar (10 lb/in.

) above the operating pressure in the boiler. The

maximum safety valve setting is 0.7 bar (10 lb/in.

) above the

maximum design operating pressure of 6 bar (87 lb/in.

Cold Feed/Open Vent
The independent cold feed and the open vent must comply
with BS. 6644 and be of the following minimum size.

WATER CONNECTIONS

GAS CONTROLS

Control is by automatic ignition of intermittent pilot; once the
presence of a flame has been proved the single (or double) main
gas valves open to give full heat input. The mains voltage supply
is via a terminal plug connection at the control box.

ELECTRICAL CONTROLS

The boiler is supplied with 2 printed circuit boards; Board
S4561B1054 is the ignition board containing the flame proving
logic and the on-board spark generator. Board W4115A1020
contains the electronic thermostat and the pump overrun timer. A
preset overheat thermostat is also fitted. The control box displays
neons indicating boiler status as follows:

Boiler on

Lockout

Overheat

A 4 minute anticycle delay is built in to the controls to prevent rapid
cycling.

FROST PROTECTION

Frost protection is incorporated in the boiler as long as there is a
permanent live supply wired to terminal L1 on the terminal plug-in
connection at the control box and the boiler thermostat knob is not
switched to off.

If the temperature sensed by the boiler thermostat falls to about
5

C the boiler will fire until the temperature reaches 18

C. Note

that this is designed to protect the boiler and may not necessarily
protect the remote parts of the system.

OPTION KITS

Remote indication kit
This kit gives the facility of remote indication of the boiler status.

Pressure gauge kit
In addition to the above control kit, an optional pressure gauge
is also available for the range of boilers. Details for fitting are
included with the pressure gauge.

Downdraught thermostat kit
This kit is optional when used on a single CXA/H installation, but
mandatory when used on a multiple boiler installation.

DUTY

The range of boilers is suitable for: Combined indirect pumped
domestic hot water and central heating systems; Independent
indirect pumped domestic hot water or central heating systems.

Fully pumped systems may be open vented or sealed.

The range of boilers is NOT suitable for:

1. Gravity DHW systems.
2. Gravity heating systems.
3. Direct domestic hot water supply.

WATER CIRCULATION SYSTEM

Due to the compact nature of the boiler the heat stored within the
castings at the point of shutdown of the burner must be dissipated
into the water circuit in order to avoid the overheat thermostat tripping.
In order to allow pump operation after burner shutdown the boiler
control box incorporates a pump overrun facility which operates for
approximately 6 minutes after burner shutdown and, in order to
make use of this, the pump must be wired to the appropriate
terminal L2 (pump) in the boiler control box.

1. The minimum flow rate as given in Table 4 must be

maintained whenever the boiler is firing and during the pump
overrun period.

2. During the period of pump overrun there must be an open

circuit of adequate water volume and/or load. The minimum
size of this circuit is given by the use of Graph 1.

Examples shown on Graph 1

a. For the CXA 90/H and CXA 100/H the minimum circuit during

pump overrun could be a load of 6 kW with a volume of 31
litres or any other combination given by the relevant line.

b. For the CXA 70/H and CXA 80/H the minimum circuit during

pump overrun could be a load of 2 kW with a volume of 45
litres or any other combination given by the relevant line.

157290-3.pmd

11/7/2005, 11:09 AM

Concord CXA/H -

Installation and Servicing

GENERAL

POSITION OF BOILER

Minimum clearances required
from walls or other fixed objects
to allow for the free access of
combustion air are shown in
Table 3 above.

However, for maintenance
purposes we suggest a
minimum rear clearance of
50mm.

Any combustible material
adjacent to the boiler and its
flue system must be so placed
or shielded as to ensure that
its temperature does not
exceed 65

C (150

F).

MULTIPLE BOILER INSTALLATIONS

The minimum installation clearances must conform to the
dimensions given below:

CXA 40/H, 50/H, 60/H, 70/H & 80/H

Clearance between boilers = 50mm
Clearance at both ends of the multiple installation = 50mm*

CLEARANCES & DIMENSIONS

Table 3

CXA 90/H, 100/H, 110/H & 120/H

Clearance between boilers = 100mm
Clearance at both ends of the multiple installation = 100mm*

Rear clearance: sufficient clearance should be given at the rear
of the boiler for connection of gas and water pipework.
*Additional clearance is required for access at either end of the
installation.

100

CON5220

Example A

Example B

CXA

100/H & CXA

90/H

CXA

80/H & CXA

70/H

CXA

40/H

CXA

60/H & CXA

50/H

Heat Load During Pump Overrun (kW)

Water Volume in Circuit during Pump Overrun (litres)

Relationship between load and water volume for the

minimum capacity of water circuit during the 6 minute

pump overrun period for different boiler outputs.

Graph 1 - Heat Load / Water Volume

CXA

110/H & CXA

120/H

10 20 30 40 50 60 70 80 90 100 110 120 130 140 150

190 200

160 170 180

120

110

100

Graph 2 - Hydraulic Resistance

Hydraulic Resistance (mbar)

Flow (litres/min)

C(20

F) - CXA

40/H

C(20

F) - CXA

50/H

C(20

F) - CXA

60/H

C(20

F) - CXA

70/H

C(20

F) - CXA

80/H

C(20

F) - CXA

90/H

C(20

F) - CXA

100/H

C(20

F) - CXA

10/H

C(20

F) - CXA

120/H

CON5221

Boiler Size

CXA 40/H

CXA 50/H

CXA 60/H CXA 70/H CXA 80/H

CXA 90/H CXA100/H CXA110/H CXA120/H

No. of sections

Front clearance mm (in)

750 (29

1/2

)

Rear clearance mm (in)

150 (6)

300 (12) 300 (12) 300 (12) 300 (12)

Side clearance mm (in)

50 (2)

100 (4)

Dimension A

m m

750

882

1042

1212

1385

1/2

3/4

1/2

Dimension B

m m

108

122

135

190

160

1/4

7/8

3/8

1/2

1/4

Dimension C

m m

931

893

5/8

7/8

3/8

3\16

3/16

Dimension D

m m

177

187

224

271

321

3/8

7/8

5/8

Dimension E

m m

116

163

213

3/4

1/8

5/8

1/2

3/8

157290-3.pmd

11/7/2005, 11:09 AM

Concord CXA/H

- Installation and Servicing

GENERAL

Particular reference should be made to BS. 6644: Section 2;
Subsection 10 and Guidance note PM5 "Automatically
controlled steam and hot water boilers" published by the
Health and Safety Executive.

The information and guidance given below is not intended
to override any requirements of either of the above
publications or the requirements of the local authority, gas or
water undertakings.

Other British Standards applicable are BS.5422 and
BS.6700.

The information provided is based on the following
assumptions:

1. An independent open vent/safety pipe connection is

made to the redundant boiler flow tapping or is
positioned immediately after the system flow pipe
connection to the header, as shown.

2. An independent cold feed/expansion pipe connection is

made to the redundant boiler return tapping. Cold feed/
expansion pipe connections made to the pumped
system return will result in an increase in the static head
requirement, caused by the additional resistance of the
distributor tube. Surging may also increase.

3. The maximum flow rate through the boiler is based on a

temperature difference of 11 °C at full boiler output and
the circulating pump is positioned in the flow to the
system.

4. The boiler is at the highest point of circulation in the

system. Systems designed to rise above the boiler flow

Note A. This minimum height must be
increased, if necessary, to comply with the
minimum head required by the pump
manufacturer in order to avoid cavitation.

Note B. This diagram does not show safety
valves, water flow switches, etc., necessary for
the safe operation of the system.

tappings will automatically require a minimum static head higher
than that shown.

5. The position of the open vent/safety pipe above the expansion

cistern water level is given as a guide only. The final position will
depend upon the particular characteristics of the system. Pumping
over of water into the expansion cistern must be avoided.

The above circuit capacity during pump overrun may be
achieved either by provision of an adequate bypass circuit
or by ensuring that a zone of suitable size is open for
circulation during this period by relevant control of zone
valves or pumps.

The wiring diagrams in Frames 17, 18 & 19 illustrate the
control methods for achieving the above.

3. Pump selection should take account of the hydraulic

resistance given in Graph 2.

PUMP POSITIONS

Whenever practically possible the circulating pump(s) should be
positioned so that it pressurises the system being served. The
vertical distance between the pump(s) and any cold feed and
expansion cistern MUST comply with the pump manufacturers
requirements in order to avoid cavitation. These requirements
override the information given in Frame 3 if the static head required
for the pump(s) exceeds that required for the boiler.

MINIMUM FLOW OF WATER - Refer to Table 4

The system design must provide for an adequate flow rate through
the boiler at all times when the boiler is firing. The minimum flow
rate should correspond to a temperature difference across the
boiler flow and return of 35

C (63

F), assessed at catalogue

rating.

3 OPEN VENTED SYSTEMS - Minimum static head requirements

WATER TREATMENT FOR HOT WATER AND
HEATING BOILERS

There is a basic need to treat the water contained in all heating
and indirect water systems, particularly open vented systems. It is
assumed, incorrectly, that because boilers are operating in
conjunction with what is apparently a closed circuit an open vented
system will not, under normal circumstances, allow damage or
loss of efficiency due to hardness salts and corrosion once the
initial charge of water has been heated up a few times.

1mm of lime reduces the heat transfer from metal to water by 10%.

Table 4 - Flow rates for fully pumped systems

Boiler

Minimum flow rates for a

temperature difference of 35

C (63

l/s

g.p.m.

CXA 40/H

0.28

3.7

CXA 50/H

0.34

4.5

CXA 60/H

0.41

5.4

CXA 70/H

0.48

6.3

CXA 80/H

0.55

7.3

CXA 90/H

0.62

8.2

CXA 100/H

0.68

CXA 110/H

0.75

9.9

CXA 120/H

0.82

10.9

CON5349

157290-3.pmd

11/7/2005, 11:09 AM

Concord CXA/H -

Installation and Servicing

GENERAL

In practice the deposition of these salts is liable to cause noises
from the boiler body or even premature boiler failure. Corrosion
and the formation of black iron oxide sludge will ultimately result
in premature radiator failure.
Open vented systems are not completely sealed from the
atmosphere if proper venting and expansion of system water is
to be achieved. The same tank is used to fill the system with
water and it is through the cold feed pipe that system water
expands into the tank when the boiler passes heat into the
system. Conversely, when the system cools, water previously
expelled is drawn back from the tank into the system together
with a quantity of dissolved oxygen.
Even if leakage from the heating and hot water system is eliminated
there will be evaporation losses from the surface of the tank which,
depending upon ambient temperature, may be high enough to
evaporate a large portion of the system water capacity over a full
heating season.
There will always be corrosion within a heating or hot water system
to a greater or lesser degree, irrespective of water characteristics,
unless the initial fill water from the mains is treated. Even the
water in closed systems will promote corrosion unless treated.
For the reason stated, Caradon Ideal Limited strongly recommend
that, when necessary, the system is thoroughly cleaned, prior to
the use of stable inhibitor, which does not require continual topping
up to combat the effects of hardness salts and corrosion on the
heat exchangers of the boiler and associated systems.
Caradon Ideal Limited advise contact directly with specialists on
water treatment such as:
Fernox Manufacturing Co. Ltd., or
Tandem House,
Marlowe Way,
Croydon.
Surrey CRO 4XS
Tel 0870 601 5000

Pressure vessels used must comply with BS. 4814 and must
be sized on the basis of the total system volume and initial
charge pressure.

Initial minimum charge pressure should not be less than 0.5
bar (7.2 psi) and must take account of static head and
specification of the pressurising equipment. The maximum
water temperatures permissible at the point of minimum
pressure in the system are specified in Guidance Note PM5.

When make-up water is not provided automatically it will be
necessary to fit controls which shut down the plant in the event
of the maximum system pressure approaching to within 0.35
bar (5 psi) of safety valve setting.

Other British Standards applicable to commercial sealed
systems are:-

BS. 6880: Part 2.
BS. 1212
BS. 6281: Part 1
BS. 6282: Part 1
BS. 6283: Part 4

Working pressure 6 bar maximum.

Particular reference should be made to BS. 6644: Section 6
and Guidance note PM5 "Automatically controlled steam and
hot water boilers" published by the Health and Safety
Executive.

The information and guidance given below is not intended to
override any requirements of either of the above publications or
the requirements of the local authority, gas or water
undertakings.

In general commercial closed pressurised systems are
provided with either manual or automatic water make up.

On both instances it will be necessary to fit automatic controls
intended to protect the boiler, circulating system and ancillary
equipment by shutting down the boiler plant if a potentially
hazardous situation should arise.

Examples of such situations are low water level and operating
pressure or excessive pressure within the system. Depending
on circumstances, controls will need to be either manual or
automatic reset. In the event of shutdown both visual and
audible alarms may be necessary.

requirements of the Gas Safety Regulations, current I.E.E.
(BS.7671) Regulations, Model Water Bye-laws, local water authority
bye-laws and it should also comply with any relevant requirements
of the local gas region, local authority and the relevant British
Standard Codes of practice and building regulations.

FOR SMALL PIPE INSTALLATIONS
BS. 6891;

Installation of low pressure pipework

FOR LARGE PIPE INSTALLATIONS

Gas Installations
IGE-UP-1:

Purging Procedures of Non-domestic Gas
Installations. Soundness Testing Procedures
for Industrial and Commercial.

IGE-UP-2:

Guidance notes on the Installation of Gas
Pipework, Boosters and Compressors in
Customer's Premises Equal to or Greater than
25mm (Non-domestic).

IGE-UP-10:

Installation of Gas Appliances in Industrial and
Commercial Premises.

BS.6644:

Installation of Gas Fired Hot Water Boilers
70kW to 1.8MW (net).

BS 6880 Pt 1-3: Water Supply.
CP342:2:

Centralised Hot Water Supply.

Model Water Bye-laws
Manufacturers notes must not be taken, in any way, as overriding
statutory obligations.

FOUNDATION

The boiler must stand on a non-combustible floor (i.e. concrete
or brick) which must be flat, level and of a suitable load bearing
capacity to support the weight of the boiler (when filled with
water) and any ancillary equipment.
If the boiler is mounted on a plinth then the dimensions must
exceed the plan area of the boiler by at least 75mm on each
side.

SEALED (PRESSURISED) SYSTEMS

INSTALLATION REQUIREMENTS

The appliance must be installed by a CORGI registered installer.
The installation of the boiler must be in accordance with the relevant

Sentinel Division
Betz Dearborn Ltd.,
Widnes,
Cheshire, WA8 8UD
Tel. 0151 424 5351.

157290-3.pmd

11/7/2005, 11:09 AM

Concord CXA/H

- Installation and Servicing

GENERAL

Position ventilation grilles to avoid the risk of accidental
obstruction by blockage or flooding. If further guidance on
ventilation is required then consult BS.6644 and BS.5440:2.:
2000

AIR SUPPLY BY MECHANICAL VENTILATION

The supply of air by mechanical means to a space housing the
boiler should be by mechanical inlet with natural or
mechanical extraction. Mechanical extract ventilation with
natural inlet must NOT be used.

Where a mechanical inlet and a mechanical extract system is
applied, the design ventilation flow rates should be as in Table
4 of BS.6644.

The requirements for air supply by mechanical ventilation are
given in BS.6644.

Note. For mechanical ventilation systems an automatic control
should be provided to cause safety shutdown or lockout of the
boiler(s) in the event of failure of air flow in either inlet or extract
fans.

IMPORTANT. The use of an extractor fan in the same room as
the boiler (or in an adjacent, communicating room) can, in
certain conditions, adversely affect the safe operation of the
boiler. Where such a fan is already fitted (or if it is intended to
fit an extractor fan after installation of the appliance) the advice
of the Gas Region should be obtained.

Tests for spillage of products from the draught diverter when
the extractor fan is running and all doors and windows are shut
should be carried out after installation. If spillage is detected,
the area of permanent ventilation must be increased.

CHIMNEY SYSTEM

To ensure the safe and satisfactory operation of the boiler the
chimney system (which may be common or individual, in the
case of twin or multiple boiler installations) must be capable of
the complete evacuation of combustion products at all times.
The effective height of the chimney terminal(s) above the boiler
outlet(s) must ensure sufficient buoyancy to overcome the
resistance of the bends, tees and runs of the flue pipe involved
and shall terminate in a down draught free zone. The number of
bends and lengths of horizontal flue pipe used should be kept to
a minimum in order to reduce gas flow resistance.

Compliance with the recommendations made in BS.6644,
IGE UP/10 Installation of Gas Appliances in Industrial and
Commercial Premises and the Third Edition of the 1956 Clean
Air Act Memorandum' should be strictly observed where
applicable.

The chimney design should avoid the formation of excessive
quantities of condensate. For this reason it is recommended
that all chimneys are insulated and lined. In the case of brick or
similar structures a stainless steel rigid or flexible flue liner
(grade 304/316) may be used in conjunction with a 50 mm
(minimum) thick layer of vemiculite or perlite granules between
the liner and the inner skin of the chimney body. Liners should
be sealed at both top and bottom.

As the Concord CXA/H range of boilers is supplied complete
with an integral draught diverter, a diverter MUST NOT be fitted
within the chimney system.

Drainage points positioned at the bottom of all vertical chimney
sections should be provided. Drain pipes should be no less
than 25 mm I.D., manufactured from acid condensate resistant
material such as stainless steel and be positioned so that pipe
runs and discharge points are not subject to the effects of frost
and that flue gases cannot leak into the boiler room.

Care should be taken to ensure the specification of the chimney
is suitable for the application by reference to the manufacturers
literature. Caradon Ideal Limited can offer advice on the design
of suitable chimney systems.

GAS SUPPLY

If there is any doubt regarding the capacity of the gas meter, the
available gas pressure, the adequacy of existing service pipes
or the size required for new service pipes then the advice of the
gas region should be requested.

Installation pipework should be fitted and tested for gas
soundness in accordance with BS. 6891;

IGE-UP-1 for small installations

IGE-UP-2 for large installations.

The local gas region must be consulted if it is necessary to
employ a gas pressure booster.

ELECTRICAL SUPPLY

WARNING. This appliance must be efficiently earthed.

A 230 V - 50 Hz mains supply is required, fused at 5 amps.

Wiring external to the appliance MUST be in accordance with the
I.E.E. (BS. 7671) Wiring Regulations and any local regulations
which apply.

For details of connections refer to Frame 14.

VENTILATION

Safe, efficient and trouble-free operation of open flued gas
boilers is vitally dependent on the provision of an adequate
supply of fresh air to the room in which the appliance is
installed. Ventilation by grilles communicating to the outside
air is required. The minimum free area and required
positioning of these grilles must be in accordance with Tables
5 & 6.

Table 5 (to BS5440)
CXA 40/H-60/H boilers installed in a room or internal space

Boiler size

Air vent free area cm

202

247

304

This air vent shall be direct to outside air or to a room or
internal space itself with an air vent to outside air of the same
size.

Table 6 (to BS6644)
CXA 70/H-120/H boilers
Required area (cm

) per kW of total rated input (net)

Boiler room

Enclosure

Low level (inlet)

High level (outlet)

Note: Where a boiler installation is to operate in summer
months (e.g. DHW) additional ventilation requirements
are stated, if operating for more than 50% of time (refer
to BS6644).

157290-3.pmd

11/7/2005, 11:09 AM

Concord CXA/H -

Installation and Servicing

INSTALLATION

CASING PACK contains:

Front panel ...................... 1 off

Side panel....................... 2 off

Top panel ........................ 1 off

Top support bracket ........ 2 off

Flue brush....................... 1 off

Casing hardware pack ... 1 off

Legend
1. Cleanout cover
2. Collector hood
3. Middle section
4. Section alignment rings & 'O' rings
5. End section
6. Gas cock

10. Burner manifold assy.
11. Base plate
12. Combustion chamber

7. Drain cock
8. NOx duct
9. Front plate

CONCORD CXA/H BOILER ASSEMBLY - Exploded view

PACKAGING

Check that all these packages are complete and have been
correctly received on site.
Factory assembled boilers are despatched from the works as

fully packaged units comprising:
1. Assembled boiler body (with distributor tube) on a wooden

pallet base enclosed in a wooden crate.

2. Carton containing the casing, fastenings and flue brush.
3. Carton containing the installation pack and instruction books.
4. Carton containing the control box.

INSTALLATION HARDWARE PACK contains:

M10 washer ..................................... 4 off

Split pin ............................................ 1 off

Strain relief bush ............................. 1 off

M10 x 25 Hex. Hd. screw ................. 2 off

M10 x 35 Hex. Hd. screw ................. 2 off

Gasket EPDM Type EP600 .............. 3 off

Plug 2" taper Sq.Hd. ........................ 3 off

Installation/Service instructions ...... 1 off

User's instructions .......................... 1 off

Flange RC 1" ................................... 1 off

2" BSP Flange (distributor tube) ...... 1 off

2" Installation pipe (handling bars) . 2 off

Thermostat pockets ......................... 2 off

13. Section bolt
14. Distribution tube
15. Tie rods
16. Thermostat pocket
17. Spillage skirt
18. Gas pipe

Con 1942

Alignment notches

Distribution tube detail

INST

ALLA

TION

157290-3.pmd

11/7/2005, 11:09 AM

Concord CXA/H

- Installation and Servicing

INSTALLATION

PACKAGING AND BOILER REMOVAL

1. Remove the casing carton and outer packaging

frame.

2. Remove the casing pack support frame.

3. Remove the distributor tube pack, controls package

and installation pack.

4. Remove the 2" BSP steel handling bars from the

installation pack.

5. Remove the 4 base bolts holding assembly to the

packaging base.

6. Remove the wood screws securing the front cross

member on the packaging base.

7. Remove the gas cock by unscrewing the union and

screw in the handling bars into the 2 front tappings.
Protect the exposed inlet gas union from ingress of
dirt.

8. Knock out the front spacing blocks from the packaging

base, ensuring that the boiler assembly is supported,
using 2" BSP handling bars.

9. Using the handling bars, manoeuvre the boiler forwards

on the packaging base and slide over collapsing base on
to the floor.
Note. Before manoeuvring the boiler into its final position
see Frame 8

c. Fit the 2 thermostat pockets. Refer to Frame 9.

Note. Frame 9 shows the relationship between
the overheat thermostat and the flow tapping.

d. Complete the water connections by plugging the

2 front top tappings with the 2" BSP plugs
provided.

1. Fit the distributor tube (supplied with the boiler) into

one of the return connection. That is one of the rear
lower ports - refer to Frame 5.

Fit the flange, using the M10 x 35mm screws and
washers provided.

Ensure that the notch in the tube flange sits correctly
into the groove on the section and that the 2 sealing
gaskets are correctly assembled on the tube.

2. Fit the 1" tapped flange to the other lower rear

connection, using the gasket and M10 x 25mm
screws and washers provided.

3. Temporarily screw the 2 handling bars (2" pipe) into

the top tappings and manoeuvre the boiler into
position.

4. Complete the system connections, using suitable

jointing compound, as follows:

a. The flow connection may be made to either of the

rear top tappings (either at the same side as the
return or opposite the return).
To avoid air locks, any reduction in pipe size must
be made in the vertical plane or achieved by using
eccentric bushes.

b. The 1" tapping in the redundant return flange may

be used for the cold feed on an open system or
connection of a pressure vessel if on a sealed
system.
If not required for this purpose it should be
plugged.

BOILER ASSEMBLY

INST

ALLA

TION

157290-3.pmd

11/7/2005, 11:09 AM

Concord CXA/H -

Installation and Servicing

INSTALLATION

1. Unpack the control box from its carton and release the

temperature sensing probe strapped to the back of the
box.
The boiler casing should now be fitted.
A casing hardware pack contains all the screws required
for assembly.

2. Slide the bottom of the side panels on to the location

buttons on the base tray.

3. Screw the side panel to support angles. Repeat for the

other side.

Position the overheat thermostat phial into the thermostat
pocket at the opposite side to the flow pipe. The illustrations
below show the rear of the boiler with the flow and relative
overheat thermostat positions.

Ensure that the overheat thermostat phial and control sensor
are correctly secured in the pockets. Refer to Frame 13.

SYSTEM CONNECTIONS

One flow and return connection should be made to the
rear of the boiler - either on one side or opposite sides.

The distributor tube and gaskets, supplied with the boiler,
must be connected into the pumped return connection.
Refer to Frame 8.

Two thermostat pockets are supplied in the installation
pack. These must be fitted in the 2 top 1/2" BSP tappings
at either side of the rear of the heat exchanger.

10 FLUE CONNECTION

1. Complete the flue connection.

2. The boiler is designed to accept flues to

BS. 835 and should be sealed with an
approved boiler putty.

11 GAS CONNECTION

1. Connect the gas

supply to the gas
inlet pipe at the
rear LH side of the
boiler.

2. Table 2 gives

details of the inlet
connection size
and the minimum
working
pressures.

CASING ASSEMBLY

INST

ALLA

TION

157290-3.pmd

11/7/2005, 11:09 AM

Concord CXA/H -

Installation and Servicing

INSTALLATION

The internal wiring of the boiler control box is shown in Frame
16.
Wiring should be in four core PVC insulated cable, not less than
0.75mm

(24/0.2mm). All fuses must be ASTA approved to BS.

1362.
The length of the conductors between the cord anchorage and
the terminals must be such that the current carrying conductors
become taut before the earthing conductor, if the cable or cord
slips out of the cord anchorage.
The boiler can be controlled either by volt-free external contacts
connected between terminals X1 and X2 or by a switched live
supply brought to X2 (after removal of the factory-fitted link between
X1 and X2), accompanied in each case by a permanent live supply
to terminal L1.
If a separate frost thermostat is fitted it must be wired across the
time switch contacts and if frost is likely the system should be
turned off using the time switch settings - all other controls
including the boiler thermostat knob should be in the normal
running position.
The earth connections MUST NEVER be omitted.
Wire the earths as shown in Frames 13 and 16.
All wiring between entry at the rear of the boiler and the
connection box must be secured neatly under the cable clips
provided.
Wiring must never be allowed to come into contact with the hot
boiler body.
Do not wire these connections in conduit up to the boiler as this
will make it impossible to remove the control box for servicing or
maintenance.
If fitted, a flow switch should be wired between F1 and F2 on the
terminal plug in connector on the bottom box at the rear of the
control box.

Connection must be made in a way that allows complete
isolation of the electrical supply - such as a double pole
switch, having a 3mm (1/8") contact separation in both poles,
or a plug and socket serving only the boiler and system
controls. The means of isolation must be accessible to the
user after installation.
This should serve only the boiler, together with its controls
and pumps. The unswitched live supply, which the boiler
requires to allow the pump overrun facility to operate, should
be controlled by the above switched/fused supply, but should
connect from there directly to the boiler and not via any
automatic time or temperature controls.
The switched live supply should be subject to control by time
and temperature controls in the usual way.
The controls incorporate a pump overrun facility, which is
necessary to dissipate residual heat on plant shutdown. It is
essential, therefore, that the main pump (and shunt pump if
fitted) is wired to the pump terminals marked L2

, N and Earth

on the plug-in terminal strip on the top box at the rear of the
control box.
The mains supply to the boiler must be wired to the boiler
terminals L1, N and Earth on the plug-in terminal strip. This
live connection must be unswitched, that is a supply not
interrupted by any automatic temperature or time control, to
enable the pump overrun (and the frost protection facility) to
operate.
Failure to operate this procedure will result in nuisance
overheat thermostat operation.
If the down draught flue thermostat is to be fitted then the link
(marked TTB) should be removed from the plug-in connector.

14 ELECTRICAL CONNECTIONS

15 CONTROLS ASSEMBLY

Remove the 2 screws from the box at the bottom of the
control box back panel and push in the terminal plug-in
connector containing the gas valve wiring harnesses;
secure with the 2 screws.

Fit the earth terminals to the earth post at the left hand
side of the control box back panel.

Undo the 2 screws securing the control box front panel
and carefully lower it. Undo the stress relief clamp
situated on the left hand side of the control box above
the grommeted hole.

Free the sleeving containing the spark electrode lead
and the flame detector lead and pass the terminals
and sleeving through the grommetted hole; connect
them to the appropriate terminals of the S4561B1054
PCB; refer to wiring diagram Frame 16.

Refit the stress relief clamp ensuring that the sleeving
passes through the clamp before tightening.

Flame detector lead
terminal

Spark electrode lead
terminal

PCB S546B1054

Grommetted hole

Con 1966

Stress
relief
clamp

INST

ALLA

TION

157290-3.pmd

11/7/2005, 11:28 AM

Concord CXA/H -

Installation and Servicing

INSTALLATION

IMPORTANT

Three zones are illustrated but the principles may be
extended as required, provided the above conditions are
met. Each relay will then require as many contacts as there
are zones.

Overrun

Since any zone may be the load during overrun, all zones
MUST individually be able to satisfy the conditions in the
foregoing paragraph. If not all zones can do this then
consider other means of control detailed on other sheets.

17 ZONES WITH BI-DIRECTIONAL MOTORISED VALVES

Normal operation

When any thermostat is satisfied while others are calling for
heat, power is available via relay contacts to close the valve for
that zone. When all thermostats are satisfied (also when the
clock period ends) all relays will be off, so the zone valves
which were open will remain open for the pump overrun. At the
start of the next call for heat (or the next clock period) valves on
zones not calling for heat will motor shut.

INST

ALLA

TION

157290-3.pmd

11/7/2005, 11:09 AM

Concord CXA/H

- Installation and Servicing

INSTALLATION

19 ZONES WITH SPRING-RETURN MOTORISED VALVES

IMPORTANT

Three zones are illustrated but the principles
may be extended as required, provided the
above conditions are met. Only one relay is
required, irrespective of the number of zones.

Overrun
During overrun and dormant periods, Zone
Valve 1 is held open. This zone, therefore,
must satisfy the conditions in the foregoing
paragraphs and Graph 1.

Normal operation
During a call for heat on Zone 1 only, the
boiler energises via Zone 1 thermostat and
the normally closed contacts of the relay.

During a call for heat on other zone(s), the
relay will be energised by the auxiliary switch
on the zone valves. This provides power to
energise the boiler. If, in addition, Zone 1
now calls for heat, its thermostat will open
Zone 1 valve via the normally open contacts
of the relay.

IMPORTANT

Terminal L2 may control the appropriate
pump(s) directly, provided that the total
running or starting current does not
exceed 6A (resistive or inductive): if this
rating would be exceeded then
appropriate switchgear must be used to
control the pumps indirectly.
Three zones are illustrated but the
principles may be extended as required,
provided the above conditions are met.
For each zone (except Zone 1) a relay
with 2 C/O contacts is required.
Overrun
During overrun periods, Zone 1 pump
performs the overrun facility; this zone,
therefore, must satisfy the conditions in
the foregoing paragraphs and Graph 1.
Normal operation
During a call for heat on Zone 1 only,
Zone 1 thermostat energises the boiler,
which in turn energises Zone 1 pump
from terminal L2.
During a call for heat on other zones, the
appropriate relay directs power to L1 to
energise the boiler, at the same time
ensuring that Zone 1 pump is controlled
by Zone 1 thermostat.

When the clock period ends, Zone valve 1 will (stay) open via normally
closed relay contacts to achieve pump overrun.

18 ZONES WITH INDIVIDUALLY PUMPED ZONES (3 zones shown)

INST

ALLA

TION

157290-3.pmd

11/7/2005, 11:09 AM

Concord CXA/H -

Installation and Servicing

INSTALLATION

GENERAL

Check that all drain cocks are closed, that any stop valves
fitted to the flow and return pipes are open and that the
system has been filled and properly vented.

PURGING

Check that the electricity supply is switched OFF.

Remove the casing lower front panel.

Extinguish all naked lights and open all doors and windows.
DO NOT SMOKE. Check that the gas supply is turned ON at
the meter and open the main gas inlet cock. Loosen the
union and allow air to be purged from the gas line until gas
is smelled. Refer to BS 6891 or IGE-UP-1 for further details.
Retighten the union.

TESTING FOR GAS SOUNDNESS

Close the gas supply cock at the meter.

Remove the screw in the inlet pressure test point (Frames
21/22) and connect a gas pressure gauge to the test point.
Take particular care to ensure a gastight connection. Open
the gas supply cock at the meter and the appliance gas
cock; record the static pressure. Next, close the gas
supply cock at the meter. Wait for 1 minute for temperature
stabilisation then observe the pressure gauge over a
period of 2 minutes.

Any leaks must be cured.

Replace all pressure test point screws.

21 INITIAL LIGHTING

1. Check that the boiler thermostat knob on the control box is

OFF.

2. Ensure that the main gas inlet cock is open (groove in the

square head in line with the pipe).

3. Press in the overheat reset button.

4. Switch on the electrical supply to the boiler.

5. Turn the boiler thermostat knob on the control panel to

number 6.

6. If the boiler does not light at the end of its ignition period, the

LEGEND
1. Thermostat knob
2. Main gas inlet cock
3. Overheat thermostat

reset button

lockout light will be illuminated. Press in and release the
lockout reset button on the control box. The controls will
reset and after a period of time will attempt to relight.

7. Once the pilot has lit, the controls will open the main gas

valves and the main burners will light. The burner on light
will be illuminated.

8. When the boiler has lit, check all connections for tightness

using leak detection fluid.

9. Set the boiler thermostat knob to the required setting.

10. Turn off the electrical supply to the boiler at the mains.

4. Lockout light
5. Lockout reset button
6. Burner on light
7. Control box

8. Control panel
9. Main gas controlvalve
10. Manifold pressure setting adjuster
11. Overheat light

Con 1967

INST

ALLA

TION

157290-3.pmd

11/7/2005, 11:09 AM

Concord CXA/H

- Installation and Servicing

INSTALLATION

22 GAS PRESSURE

MANIFOLD PRESSURE

The manifold setting pressure must now be checked and
adjusted as necessary.

Start the adjustment procedure with the system cold, on full
load and with all temperature controls set to maximum to
avoid thermostatic shutdown. Remove the blanking screw in
the manifold setting pressure test point and connect a suitable
gas pressure gauge.
Turn on the electrical supply light the boiler and let it operate
for about 10 minutes to stabilise the burners. Check the
pressure and if necessary adjust it as follows:
CXA 40/H-80/H boilers:

The location of the manifold pressure adjuster on the gas
valve is shown in Frame 21. Remove the dust cover and, using
a screwdriver, turn the screw clockwise to increase or anti
clockwise to decrease the pressure, until it is set to the value
in Table 1.
CXA 90/H and 100/H boiler:

The setting procedure must be done in 2 steps. The location
of the of the manifold pressure adjuster on the gas controls is
shown in Frame 21. Unscrew the bottom electrical plug on the
LH gas valve and pull it off. Remove the dust cover and set the
adjuster on the RH gas valve to the value given in Table 7.
Refit the gas valve electrical plug then set the adjuster on the
LH gas valve to give the burner pressure given in Table 7.

Failure to follow this procedure may result in the correct burner
pressure being set but the 2 gas valve governors not working
correctly.

CXA 110/H and 120/H boilers:
The setting procedure must be done in 2 steps. The location
of the of the manifold pressure adjuster on the gas controls is
shown in Frame 21. Remove the dust cover and, using a
screwdriver, screw in the adjuster on the LH valve nearly fully.
Set the adjuster on the RH gas valve until the manifold
pressure is at the value given in Table 7. Unscrew the LH gas
valve adjuster until the manifold pressure falls then screw it in
again until the pressure is set at the value given in Table 7.

Failure to follow this procedure may result in the correct burner
pressure being set but the 2 gas valve governors not working
correctly.

Table 7 - Manifold gas pressure settings

Check there is no spillage of combustion products from the
boiler draught diverter by carrying out a spillage test, as
detailed in BS. 5440:1.

23 SPILLAGE CHECK

24 TESTING

Check that the main burner responds correctly to manual on/
off operations of any controls fitted in the gas control circuit.
Check, in the following manner, the operation of the flame
failure safety device:

1. Extinguish the main burner and pilot burner by turning off

the main gas inlet cock.

2. The controls will go to lockout almost immediately and

the lockout light on the control panel will light.

3. Turn the gas cock again, and press in and release the

lockout reset button on the control box. After a period of
time the controls reset the boiler and it will relight.

4. Complete the commissioning section of the boiler log book.

25 ADJUSTMENT OF WATER FLOW

RATE THROUGH THE BOILER

26 HANDING OVER

ROUTINE OPERATION

Full instructions covering routine lighting and operation of the
boiler are given on the Lighting and Operation Instruction
Label located on the inside of the casing door.

Draw the attention of the boiler owner or his representative to
the Lighting and Operating Instruction Label on the inside of
the casing door. Give a practical demonstration of the
lighting and shutting down of the boiler.

Describe the function of the boiler and system controls and
show how they are adjusted and used.

Describe the function of the downdraught thermostat if fitted.

Hand these Installation and Servicing Instructions, User's
Instructions and Log book to the customer and request him
to keep them in a safe place for ready reference

IMPORTANT. Point out to the owner that the boiler must have
regular maintenance and cleaning, at least annually, in order
to ensure reliable and efficient operation. Regular attention
will also prolong the life of the boiler and should preferably
be performed at the end of the heating season.

After servicing complete the service section of the log book
and return to the owner or their representative.

Recommend that a contract for this work should be made
with the regional gas authority or a CORGI registered
heating installer.

At the end of the adjustment procedure replace the dust covers,
disconnect the gas pressure gauge and replace the blanking
screw in the manifold pressure test point.
The gas rate for each size of boiler is given in Table 1 on page 4.

When commissioning the heating/domestic hot water system
the shunt pump must be adjusted to give the minimum flow
rate given in Table 4, when that part of the system intended to
be used for dissipation of residual heat only is in operation.

RH valve adjustment

LH valve (and final)

Boiler

pressure

adjustment pressure

mbar

CXA 90/H

9.0

9.6

CXA 100/H

10.0

10.7

CXA 110/H

11.6

11.1

CXA 120/H

12.6

12.1

INST

ALLA

TION

157290-3.pmd

11/7/2005, 11:09 AM

Concord CXA/H -

Installation and Servicing

SERVICING

(CXA 120/H boiler only)
Remove four M5 securing screws retaining internal turning
baffles from side of collector hood. Slide turning baffles to rear

of collector hood void to facilitate access to flue ways for

cleaning.

27 SERVICING

Caradon Ideal Limited does not accept any liability
resulting from the use of unauthorised parts or the repair
and servicing of appliances not carried out in accordance
with the Company's recommendations and specifications.

A comprehensive service should be carried out at least
once a year. The User is advised to make a contract with
the local Gas Region or a CORGI registered heating
installer.

WARNING. ALWAYS turn OFF the gas supply at the gas
cock and switch OFF and disconnect the electricity supply
to the appliance BEFORE SERVICING OR REPLACING
ANY COMPONENTS.

Unscrew the extended nuts at the top of the NOx
duct behind the control box and lift the NOx duct
clear of the burners as illustrated below.

Undo the 4 wing nuts securing the burner front
plate. Pull the front plate forwards, at the top,
and lift it out - taking care not to damage the
insulation.

The centre and RH burners can be lifted out
after they have been pushed back to clear the
injector.

To remove LH burner the pilot gas pipe
connection at the gas valve must be removed.
The LH burner may now be removed by
pushing it back to clear the injector and lifting it
out. To remove it away from the boiler, the flame
detector lead and spark lead must be
disconnected in the control box.

Remove the 2 screws securing the control box
door, lift it and carefully drop it down. Pull off the
flame detector lead and the spark electrode
lead connections from the S4561B1054 PCB
(the left hand board). Undo the strain relief
clamp and feed the sleeved leads out of the
box. The burner can now be fully removed from
the boiler.

Undo the screws securing the clean out cover
and lift it off to give access to the flue ways.

CLEANING THE BOILER. Refer to Frame 5

Pull and lift off the lower front panel and top panel from
the boiler casing.

Con 1943

NOx duct

Con 1944

Baffle

4, Baffle screws

4, Cover screws

Remove all loose deposits from the heat exchanger,
especially from between the fins, using the brush provided,

and remove all debris from the combustion chamber floor.

Examine the burner assembly. Clean the burner bars by
brushing them down with a stiff bristle (not wire) brush. Check

each bar carefully to ensure that all flame ports are clear, that

there are no cracks and that all surfaces are free from
accumulated deposits.

If available, an industrial vacuum cleaner may be useful to

assist in this work. When cleaning the burner bars, take care

to avoid damage from rough handling to the pilot pipe,
electrodes and leads.

Inspect the pilot burner, injector, ignition electrode, and flame

detector electrode.

Ensure that they are clean and in good condition.
In particular, check that:

The pilot burner is firmly secured.

The pilot shield is clean and correctly positioned.

(Not fitted to the CXA 120/H boiler).

The ignition electrode and lead are clean, undamaged,
secure and correctly dimensioned. Refer to diagram in

Frame 28.

The flame detector electrode and lead is clean,

undamaged, secure and correctly dimensioned. Refer
to Frame 28.

5. The pilot burner head is clean and undamaged.

Note. Casing omitted for clarity

SER

VICING

157290-3.pmd

11/7/2005, 11:10 AM

Concord CXA/H

- Installation and Servicing

SERVICING

4mm

Pilot burner

Pilot draught

shield

3 - 4mm

Spark gap

Flame detector

electrode

Spark

electrode

Main burner flame ports

Pilot and electrode positions

29 REPLACEMENT OF COMPONENTS - Refer to Frame 5

GENERAL

WARNING. Always turn OFF the gas supply at the gas
inlet cock and switch OFF and DISCONNECT the
electricity supply BEFORE WORKING on the appliance.

To facilitate the replacement of components, remove and
replace the lower front panel, NOx duct and the burner front
plate as necessary -described under `Servicing'.

28 SERVICING - continued

Refit the LH burner, ensuring that the flame detector lead is
properly connected. Reconnect both electrode leads at the
S4561B1054 PCB in the control box. Ensure the sleeving passes

through the strain relief clamp before refastening it.

Refit the centre and RH burners. Ensure that care is taken not to

damage the combustion chamber insulation and that the burner
front plate fits beyond the burner retaining returns when it is

refitted.

(CXA 120/H boiler only)
Refit collector hood baffles within collector hood using M5 securing

screws.

Refit the flue clean out cover, NO

ducts, control box door, casing

top and front panels.

TESTING AFTER SERVICING

After re-assembly, restore the electricity and gas supplies. Light the

boiler (refer to the Lighting and Operating Instruction Label on the

inside of the casing front panel) and check the gas connections for
tightness, as detailed under `Testing for Gas Soundness' - Frame

20.

Check gas pressures and the gas rate; test as instructed in Frame
22 `Manifold Gas Pressure' and 'Testing'. Adjust any time and

temperature controls to User's requirements and remember to
reset any time control, which may have been switched off, to the
correct time of day. Refit the lower front panel.

1. Remove the LH burner as previously described in

Frame 27

2. Remove the 2 screws securing the control box front

panel, lift it and carefully lower it down.

3. Remove the flame detector lead and the spark lead

connections from the S4561B1054 PCB in the control
box. Undo the strain relief clamp and pass the
sleeved wires through the grommetted hole in the
back panel.

4. Remove the spark electrode by undoing the back nut.

Pull off the flame detector lead connection and
unscrew the electrode.

5. Undo the pilot pipe connection and undo the 2

screws retaining the pilot burner and remove it.

6. Fit the new pilot burner, ensuring that it faces towards

the front of the burner and that the pilot injector is in
position before connecting the pilot pipe.

7. Reassemble in reverse order, ensuring that the

spark electrode lead passes through the sleeving
and that the sleeving passes through the strain relief
clamp in the control box before retightening.

30 PILOT BURNER ASSEMBLY

Pilot burner

Pilot draught shield

(Not fitted to CXA 120/H)

Fixing screw (2)

LH burner

Flame detector

electrode

Spark electrode

Backnut

Flame detector

lead

SER

VICING

157290-3.pmd

11/7/2005, 11:10 AM

Concord CXA/H -

Installation and Servicing

SERVICING

1. Remove the LH burner as previously described in

Frame 27

2. Remove the 2 screws securing the control box front

panel, lift it and carefully lower it.

3. Remove the spark lead and flame detector lead

connection from the S4561B1054 PCB in the control
box. Undo the strain relief clamp and pass the sleeved
wires through the grommetted hole in the back panel.

4. Remove the spark electrode by undoing the back nut.

5. Fit the new electrode and reassemble in reverse order,

ensuring that the spark electrode lead passes through
the sleeving and that the sleeving passes through the
strain relief clamp in the control box before retightening.
Ensure that the push-on connections are as follows
(from left to right): spark electrode, blank, earth, flame
detector.

31 SPARK ELECTRODE AND LEAD

33 GAS CONTROL VALVE

1. Undo the pilot gas pipe connection at the gas control

valve (if required).

2. Undo the screw securing the electrical plugs on the

gas valve and lift them off.

4. Check that the gas inlet cock is OFF, unscrew the 4

screws from the inlet flange, and the 4 screws from
the outlet flange and remove the valve.
(CXA 90/H-120/H, loosen the other 4 screws on the
inlet flange securing the other gas valve).

5. Replace the gas control valve and re-assemble in

reverse order, ensuring that the arrow indicating the
direction of flow is in the correct position.

6. Ensure that a new `O' ring seal is correctly placed in

each flange connection.

7. Test for gas soundness.

34 MAIN BURNERS

1. Remove the NOx duct and burner front plate, as

previously described in Frame 27.

2. Both RH and centre burners can be removed by sliding

each one back to clear the injector, and then lifting out.

3. To exchange the LH burner remove it from the boiler as

previously described in Frame 27. Remove pilot burner
as described in Frame 30.

4. Fit new LH burner and the centre and RH burners.

Note. Ensure that the pilot burner is correctly fitted, i.e.
facing the front, and that the pilot injector has not been
omitted.

7. Reconnect the pilot gas pipe connection to the gas valve.

IMPORTANT. Care must be taken to prevent damage to the
combustion chamber insulation when replacing burners.

1. Remove the LH burner as previously described in Frame 27

2. Pull off the lead at the electrode and unscrew the flame detector

electrode.

3. Fit the new electrode and reassemble in reverse order.

4. To change the lead, remove the 2 screws securing the control

box front panel, lift it and carefully lower it. Remove the flame
detector lead and spark lead connection from the S4561B1054
PCB in the control box, undo the strain relief clamp and pass
the sleeved wires through the grommeted hole in the back
panel.

5. Pull the lead through the sleeving. The new lead must be

passed through the sleeving small fitting first.

6. Reassemble in reverse order, ensuring that the sleeving

passes through the strain relief clamp before tightening.
Ensure that the push-on connections are as follows (from left to
right): spark electrode, blank, earth, flame detector.

32 FLAME DETECTOR AND LEAD

Pilot burner

Fixing screw (2)

LH burner

Flame

detector

electrode

Spark

electrode

Backnut

Flame detector

lead

Pilot draught shield (not fitted to CXA 120/H)

Pilot burner

Fixing screw (2)

LH burner

Flame

detector

electrode

Spark

electrode

Backnut

Flame detector

lead

Pilot draught shield (not fitted to CXA 120/H)

SER

VICING

157290-3.pmd

11/7/2005, 11:10 AM

Concord CXA/H

- Installation and Servicing

SERVICING

LEGEND

Main gas inlet cock

Gas inlet union

Gas control valve

'O' ring seal

Gas inlet manifold

Main injector, 3 off

RH burner

Centre burner

LH burner

10. Overheat thermostat
11. Mounting brackets

12. Pilot draught shield
13. Flame detector electrode
14. Spark electrode

15. Pilot gas pipe
16. Pilot burner

PTP pressure test point

35 BURNER AND CONTROLS ASSEMBLY - Exploded View CXA 40/H - 80/H

36 BURNER AND CONTROLS ASSEMBLY - Exploded View CXA 90/H - 120/H

LEGEND

Main gas inlet cock

Gas inlet union

Gas control valves

'O' ring seal

Gas inlet manifold

Main injector, 3 off

RH burner

Centre burner

LH burner

10. Overheat thermostat

11. Mounting brackets
12. Pilot draught shield (not

fitted to CXA 120/H)

13. Flame detector electrode
14. Spark electrode
15. Pilot gas pipe

16. Pilot burner
PTP pressure test point

Con 1970

Con 1969

SER

VICING

157290-3.pmd

11/7/2005, 11:10 AM

Concord CXA/H -

Installation and Servicing

SERVICING

Overheat
thermostat

Reset
button

CON5231

38 CONTROL SENSOR

POTENTIOMETER ASSEMBLY

1. Undo the thermostat knob retaining screw and pull

off the knob.

2. Remove the lower front panel

3. Undo the backnut and washer retaining the

potentiometer.

4. Undo the 2 screws securing the control box front

panel, lift it and carefully lower it down.

5. Pull off the connections at the back of the

potentiometer and the plug from the PCB.

6. Fit the new potentiometer, and reassemble in

reverse order, ensuring that the connections on the
back of the potentiometer are made either to the top
2 or the bottom 2 tags and that the lug on the
potentiometer body locates through the hole in the
front panel of the control box.

39 CONTROL SENSOR

3. Slacken the 2 screws securing the control box

front panel, lift it and carefully lower it down.

4. Pull out the sensor plug from the printed circuit

board and release cable clamp from the back
panel.

5. Pull the sensor lead through the grommeted hole

in the back panel and the wire clips.

6. Fit the new sensor and reassemble in reverse

order, ensuring that the lead is rerouted along the
casing in the clips provided.

1. Remove the lower front and top panel. Refer to

Frame 27.

2. Remove the sensor from the thermostat pocket in

the rear heat exchanger section by removing the
Heyco bush.

Sensor

pocket

Sensor

lead

Heyco

bush

42 OVERHEAT THERMOSTAT

1. Remove the split pin

from the overheat
thermostat pocket
and remove the phial.

2. Unclip the capillary

from its clips on the
casing side panel.

3. Loosen the 2 x M3

screws and remove
the thermostat
assembly from its
fixing bracket.

4. Undo the screw and

remove the cover.

5. Remove the wires.

6. Undo the backnut

and remove the
thermostat.

7. Fit the new

thermostat and
secure with the
backnut.

8. Reconnect the wires as follows:

1. Pink

2. White

3. Red

Reconnect the earth terminal

9. Reassemble in reverse order.

Con 1500

PCB

Plug

Potentiometer

Backnut

Thermostat knob

Printed circuit
board

Con 1968

Cable clamp

Sensor plug

SER

VICING

157290-3.pmd

11/7/2005, 11:10 AM

Concord CXA/H -

Installation and Servicing

SERVICING

43 COMBUSTION CHAMBER INSULATION REPLACEMENT

The insulation boards used in the combustion
chambers of these products contain man-made fibres,
refractory fillers, organic and inorganic binders and as
such are deemed to be harmless to humans.

Caradon Ideal Limited, however, recommend that for
your own comfort and to comply with good working
practise the procedure described below is followed.

IMPORTANT. Turn OFF the gas and DISCONNECT the
electricity supply.

To replace the insulation boards the major boiler
components (including the heat exchanger and
burners) have to be removed to gain access to the
combustion chamber.

Prior to removal of the boards the

following protective equipment should
be worn:
· Face mask supplied with the spare part.
· Gloves supplied with the spare part.

1 Damp down the combustion chamber area containing

the insulation boards.

2. Remove the insulation boards. The replacement boards

are supplied in a plastic bag. This bag should be
retained and the discarded boards should now be
placed into it.

3. Sweep any dampened particles and place in the plastic

bag.

4. Fit new insulation boards.

5. Remove the gloves and face mask and place them in the

plastic bag.

6. Wash your hands and any areas of skin which may have

come into contact with any of the particles from the
insulation board.

7. Seal the plastic bag and dispose of it and its contents

into a commercial tip.

42 PC BOARD W 4115A1020

1. Remove the lower front panel.

2. Undo the 2 screws securing the control box front

panel. Carefully lift it up and lower it.

3. Pull off the 4 plugs from the board.

4. The board can now be removed by squeezing in the

retaining barbs.

5. Fit the new board in reverse order.

PCB

Retaining barbs

Con 1910

Plugs

SER

VICING

157290-3.pmd

11/7/2005, 11:10 AM

Concord CXA/H

- Installation and Servicing

SITE ASSEMBLY

44 INSTRUCTIONS FOR SITE ASSEMBLED BOILERS

The site assembled boiler is supplied in the following
packages:

Combustion chamber / manifold / burner assembly.

Platework package.

Casing package.

Controls box package.

End and centre sections.

TOOLS REQUIRED

Spanners

Torque wrench

Pozi screwdriver

Mallet

ASSEMBLY

The combustion chamber should be positioned as near as
possible to the installation site.

IMPORTANT. It must be remembered that the boiler
distribution tube has to be fitted into the rear return tapping of
the assembled boiler before siting.

Prior to assembling the sections it will be necessary to
remove the burner and controls assembly from the
combustion chamber.

Remove the assembly as follows:

1. Undo the 4 wing nuts securing the burner front plate. Pull

the front plate forward from the top and lift it out.

2. The right hand and centre burners may now be lifted out

after they have been pushed back to clear the injector.

3. In order to remove the left hand burner, the pilot gas pipe

connection at the gas valve must be removed.

4. The left hand burner may now be removed by pushing it

back to clear the injector and lifting it out - taking care not
to damage the pilot gas pipe while the burner is out of the
appliance.

5. Undo the nut securing the manifold assembly to the

combustion chamber, pull the manifold assembly to the
right and lift out.

GENERAL

The installation of the boiler must be in accordance with the
Gas Safety (Installation and Use) Regulations or rules in
force, building regulations, I.E.E. (BS.7671) Regulations
and the bye-laws of the local water undertaking. It should
also be in accordance with the relevant British Standard
Codes of Practice together with any relevant requirements
of the local Gas Region and local authority.

Legend
1. Cleanout cover.
2. Collector hood.
3. Middle section.
4. Section alignment

rings & 'O' rings.

5. End section.
6. Gas cock.
7. Drain cock.
8. NOx duct.
9. Front plate.

10. Burner manifold assy.
11. Base plate.
12. Combustion chamber.
13. Section bolt.
14. Distribution tube.
15. Tie rods.
16. Thermostat pocket.
17. Spillage skirt.
18. Gas pipe.

Con 1942

Alignment notches

Distribution tube detail

157290-3.pmd

11/7/2005, 11:10 AM

Concord CXA/H -

Installation and Servicing

SITE ASSEMBLY

45 INSTRUCTIONS FOR SITE ASSEMBLED BOILERS - continued

17. Refit the manifold assembly.

Position the boiler insulation
over the gas line tie bracket.
Fasten the bolt securing the
bracket to the front section
before wrapping and
securing insulation around
the boiler body.

18. Insert the burner rear supports into the slots at the back

of the combustion chamber. Lift the front of the burners
over the injectors and pull forward to engage.

19. Fit the support angles (contained in the platework

package) to the collector hood. The angle with the hole
for the earth screw fits to the front.

PREPARATION OF SECTIONS

Each section should be brushed clean on all external
surfaces and any debris which may have accumulated within
the section should be removed via the bottom ports.

Section assembly - refer to exploded view, Frame 44

6. Take the back section (with 1/2" BSP tappings in the top)

and lift it onto the combustion chamber so that the
combustion chamber back panel return is inside the
section rear lip. Locate a slotted steel ring and an `O' ring
seal into each of the 4 ports. It will be necessary to
squeeze the steel ring slightly to enable it to be pushed
fully into the recess.

7. Lift a middle section onto the combustion chamber and

carefully offer it up to the back section until it engages the
projecting steel rings. It may be necessary to use a mallet
and hardwood block to ensure that the steel rings are
pushed fully into the recesses and that the sections are
butted up to each other.

Note. Until the final section is fitted and the tie rods
fastened the sections in the assembly are not fixed
together therefore CARE MUST BE TAKEN TO PREVENT
the installed section coming apart.

8. Repeat the above procedure for all of the remaining

sections until the assembly is complete.

9. Fit the 4 tie rods through the holes in the sides of the end

sections and fit a flat steel washer, a shakeproof washer
and a nut to both ends of each tie rod. Screw up all the
nuts equally, in turn, and finally tighten them to a torque of
38-41 Nm (28-30 lb. ft.).

10. Fit the distributor tube assembly as described in Frame 8.

Fit the drain cock (refer to exploded view in Frame 44).

11. On open vented systems a hydraulic test should be carried

out at 1

1/2

times the design pressure given in Table 2 for

a period of 30 minutes.

12. On a pressurised system the test should be at twice the

design pressure for a period of 30 minutes.

13. Fit the 4 coach bolts into the lugs at the bottom of the front

and rear sections. Secure with the nuts and washers
provided.

14. Fit insulation wrap to heat exchanger. Secure with clips

provided.

15. Fit the collector hood. Ensure the underside returns

running across the hood sit within the front and rear
section flueways. Fasten down, using the four M6 screws
and nuts provided, through the front and rear fixing points.

16. Locate the fibreglass rope in the rear section grooves to

form a seal with the spillage skirts. Fit the spillage skirts
onto the collector hood using the self tapping screws
provided.

20. Fit the gas inlet pipe bracket to the rear support angle, on

the LH side, using the self tapping screws.

21. Fit the gas inlet pipe and make good the union between the

gas cock and the valve inlet pipe.

22. Fit the NOx duct, using the reverse procedure to that shown

in Frame 27, and secure with the extended nuts.

23. The boiler is now ready for installation. Go to Frame 8 and

continue the installation from there.

157290-3.pmd

11/7/2005, 11:10 AM

Concord CXA/H

- Installation and Servicing

FAULT FINDING

FAUL

T FINDING FAUL

T FINDING

Allow time to purge any air

present.

Ensure that there is gas

pressure at the boiler

inlet. Check that the pilot jet

is not blocked.

Is there gas at the pilot burner ?

Is the pilot flame of the correct length ?

Clean or replace.

Is inlet pressure satisfactory ?

Is pilot burner, injector and pipe clean and

undamaged ?

YES

Pilot should

now light

Faulty PCB S4561B1054 -

replace

YES

Is there a spark at the ignition electrode ?

Before attempting any electrical fault finding ALWAYS carry out
the preliminary electrical system checks as detailed in the
Instructions for the British Gas Multimeter or other similar
commercially available meter.
The preliminary electrical system checks are the FIRST
electrical checks to be carried out during a fault finding
procedure.
On completion of any service/fault finding task which has
required the breaking and remaking of electrical connections
the following checks MUST be repeated:

Check that the gap between the electrode

and

pilot burner is 3-4 mm.

Ensure that the H/T lead and electrode are

sound, clean and undamaged and that the

connections are secure.

Check that the spark generator is operative

by carefully holding an earthed screwdriver

3mm from the H/T output terminal of PCB

S4561B1054 in the control box with the

ignition lead removed and then switching

the boiler on.

Is there a spark ?

Is the detection electrode, its lead and

connections clean, tight and undamaged ?

Check flame current; expect 1.5 µ

Faulty PCB S4561B1054 - replace

Check earth connections

YES

47 PILOT WILL NOT STAY LIT

YES

46 PILOT WILL NOT LIGHT

Earth continuity

Polarity

Resistance to earth

Detailed instructions on the replacement of faulty components
are contained in the 'Servicing' section of these Installation &
Servicing Instructions.
Before carrying out Fault Finding ensure that all external controls
calling for heat and the overheat thermostat has not operated.
There should be 230V +- 10% available at the control box
connection.

157290-3.pmd

11/7/2005, 11:10 AM

Concord CXA/H -

Installation and Servicing

FAULT FINDING

FAUL

T FINDING FAUL

T FINDING

Secure and tighten

48 PILOT LIT BUT NO MAINS GAS

Are the plugs on the gas valve(s) secure

and tight ?

YES

Are the connections at the plug-in terminal strip

at the control box secure ?

Fit new gas valve

YES

Is there 230V ±10% at the gas valve plug(s) ?

YES

Fit new S4561B1054 PCB

Refer to installation instructions for details.

49 BOILER GOES OUT ON OVERHEAT THERMOSTAT

Are the thermostat sensors in their correct

pockets ?

YES

Is there an unswitched live supply to terminal L1

on the plug-in terminal connection at the

control box ?

Is the pump (or shunt pump) wired to terminal

in the control box ?

YES

Is there sufficient open circuit water volume

or load available on boiler shut down for the

pump overrun ?

YES

Refer to installation instructions

Has boiler thermostat knob been switched to

off ? (this overrides the pump overrun facility)

YES

Replace PCB W4115A1020.

YES

Advise USER

Has the red overheat thermostat reset button
(located on thermostat housing) been reset?

YES

Press red overheat thermostat button to reset

157290-3.pmd

11/7/2005, 11:10 AM

Concord CXA/H

- Installation and Servicing

SHORT LIST OF PARTS

Key No.

Description

Qty.

Product No.

12.4

Boiler body insulation ............................... CXA 40/H

150 093

.................................................................. CXA 50/60/H

150 094

.................................................................. CXA 70/80/H

150 095

.................................................................. CXA 90/100/H

150 096

.................................................................. CXA 110/120/H

154 856

LH main burner ......................................... Worgas 0.087.751 CXA 40/H

150 153

.................................................................. Worgas 0.087.753 CXA 50/60/H

150 154

.................................................................. Worgas 0.087.755 CXA 70/80/H

150 155

.................................................................. Worgas 0.087.757 CXA 90/100/H

150 156

.................................................................. Worgas 0.087.761 CXA 110/120/H

154 812

Centre & RH main burners ....................... Worgas 0.087.750 CXA 40/H

150 149

.................................................................. Worgas 0.087.752 CXA 50/60/H

150 150

.................................................................. Worgas 0.087.754 CXA 70/80/H

150 151

.................................................................. Worgas 0.087.756 CXA 90/100/H

150 152

.................................................................. Worgas 0.087.760 CXA 110/120/H

154 811

Main burner injectors ................................ Size 3.4 mm; CXA 40/H

111 323

.................................................................. Size 3.82mm; CXA 50/H

111 324

.................................................................. Size 4.12mm; CXA 60/H

111 325

.................................................................. Size 4.57mm; CXA 70/H

111 326

.................................................................. Size 4.86mm; CXA 80/H

013 177

.................................................................. Size 5.2mm; CXA 90/H

111 328

.................................................................. Size 5.3mm; CXA 100/H

013 179

.................................................................. Size 5.5mm; CXA 110/H

157 904

.................................................................. Size 5.6mm; CXA 120/H

154 840

Pilot burner - HONEYWELL Q 349 A1067 complete with injector

077 105

Pilot burner injector - HONEYWELL 45900421-011

004 545

Gas control valve - HONEYWELL V4601 AB 1034

154 810

Gas control valve - HONEYWELL VR4605 AB 1019 CXA 90 - 120/H

111 869

Gas valve plugs and lead assy. CXA 40 -120/H

154 733

Gas valve plugs and lead assy. CXA 90 -120/H

112 431

Gas valve plugs and lead assy. CXA 90 -120/H

139 269

Ignition electrode and H.T. lead assy. ......

154 967

Flame sensing electrode .........................

154 818

Boiler status neons .................................. Burner on

154 854

.................................................................. Overheat

154 855

.................................................................. Lockout

154 855

Electronic thermostat sensor & lead assembly

154 816

Thermostat potentiometer assembly .......

154 850

Thermostat knob .......................................

170 859

Overheat thermostat .................................

155 791

Control box assembly, complete ..............

157 152

Printed circuit board S4561B1054 ...........

154 813

Printed circuit board W4115A1020 ..........

154 815

When ordering spare parts please quote:

1. Boiler model
2. Boiler serial no. (refer to the data plate on the combustion chamber)
3. Boiler B.G. P.I. No. (refer to the data plate on the combustion chamber)
4. Description
5. Quantity
6. Product no.

The following are parts commonly
required as replacements, due to
damage or expendability.

Their failure or absence is likely to affect
the safety and/or performance of this
appliance.

157290-3.pmd

11/7/2005, 11:10 AM

Concord CXA/H -

Installation and Servicing

SHORT LIST OF PARTS

Key No.

Description

Qty.

Product No.

Right hand casing side panel - white stove enamel .. CXA 40/H

111 650

..................................................................................... CXA 50/H

111 651

..................................................................................... CXA 60/H

111 651

..................................................................................... CXA 70/H

111 652

..................................................................................... CXA 80/H

111 652

..................................................................................... CXA 90/100/H

111 653

..................................................................................... CXA 110/120/H

154 898

Left hand casing side panel - white stove enamel ..... CXA 40/H

111 650

..................................................................................... CXA 50/H

111 651

..................................................................................... CXA 60/H

111 651

..................................................................................... CXA 70/H

111 652

..................................................................................... CXA 80/H

111 652

..................................................................................... CXA 90/100/H

111 653

..................................................................................... CXA 110/120/H

154 898

Casing top panel - white stove enamel ...................... CXA 40/H

111 293

..................................................................................... CXA 50/H

111 294

..................................................................................... CXA 60/H

111 295

..................................................................................... CXA 70/H

111 296

..................................................................................... CXA 80/H

111 297

..................................................................................... CXA 90/100/H

111 298

..................................................................................... CXA 110/120/H

154 897

Casing lower front panel - white stove enamel c/w lighting instructions

171 842

Casing upper front control panel (less controls) ........

154 846

Casing assembly, complete - white stove enamel .... CXA 40/H

157 389

..................................................................................... CXA 50 /H

157 390

..................................................................................... CXA 60/H

157 391

..................................................................................... CXA 70/H

157 392

..................................................................................... CXA 80/H

157 393

..................................................................................... CXA 90/100/H

157 394

..................................................................................... CXA 110/120/H

157 395

Reset Switch Assembly ...............................................

155 269

157290-3.pmd

11/7/2005, 11:10 AM