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Concord CXC -

Installation

CONTENTS

Air Supply. ........................................................................ 9

Boiler Assembly - exploded view. ............................... 10

Boiler Clearances. ........................................................... 6

Burner Assemblies - exploded views. .............................

CXC 48-70. ................................................................ 28
CXC 94-116. ............................................................... 29

Casing Assembly. .......................................................... 13

Commissioning. ............................................................. 18

Condensate Drain Connection ..................................... 12

Controls. ........................................................................... 5

Electrical Connections. ................................................. 15

Electrical Supply. ........................................................... 10

Fault Finding. ................................................................. 33

Flue System. ..................................................................... 9

Gas Connections. .......................................................... 13

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

Gas Supply. ..................................................................... 10

Hydraulic Resistance. ...................................................... 6

Initial Lighting. ................................................................ 18

Installation. ..................................................................... 10

Mandatory Requirements. ............................................... 9

Option Kits. ....................................................................... 5

Pump. ................................................................................ 7

Servicing. ........................................................................ 25

Short List of Parts. ......................................................... 36

Static Head Requirements. ............................................. 7

Ventilation. ........................................................................ 9

Water Circulation. ............................................................ 7

Water Connections. ......................................................... 5

Water Treatment. .............................................................. 8

Wiring Diagrams. ........................................................... 16

INTRODUCTION
CONSTRUCTION

BOILER BODY

The Concord CXC boiler consists of 2 basic parts; a conventional
Concord CXD boiler; plus an additional heat exchanger.

The Concord CXC boiler body is constructed from cast iron
sections, insulated by a foil backed fibre glass blanket. It is mounted
on a sheet steel combustion chamber.

An aluminiumised mild steel flue collector hood and stainless steel
condensate sump is fitted on top of this heat exchanger. The sump
supports the secondary heat exchanger which is constructed from
aluminium finned tubes between aluminium and cast iron headers.
This heat exchanger is also insulated by a foil backed fibre glass
blanket.

Above the primary heat exchanger an induced draught fan is fitted
- capable of overcoming the resistance of a 30m length of 6" flue
pipe. The boiler is supplied with header pipework between the
primary and secondary heat exchanger.

Within this pipework, a 'shunt' pump is provided to ensure an
adequate flow through the primary heat exchanger, independently
of the system pump. This also ensures that a sufficient temperature
is maintained in the primary heat exchanger to prevent corrosion.

CASING

The combined boiler bodies are enclosed in a white, stove
enamelled casing which incorporates a control panel fascia.

The casing is specially designed to ensure easy access for both
servicing and cleaning of both heat exchangers.

BURNERS

The 3 burners are of stainless steel construction.

Gas Safety (Installation and Use) Regulations, 1994,
amendments 1996 or rules in force.

It is the law that all gas appliances are installed and serviced by a
CORGI registered installer (identified by ) 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 CXC 48/116 range of boilers has been tested and
certified by British Gas to prEN656 for use with Natural gas only.

Note. The CXC 48 and CXC 70 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 Plumbing
Limited in writing. If in doubt please enquire.

Any direct connection of a control device not approved by Caradon
Plumbing 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.

Concord CXC 48-116 (Natural gas)

B.G. Certified - P.I. No. 87/AQ/340

Destination Countries: GB and IE

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Installation

Boiler

CXC 48

CXC 70

CXC 94

CXC 116

Number of sections

Flow tappings

Rc (in. BSP)

2 (2) - 1 at rear

Return tappings

Rc (in. BSP)

2 (2) - 1 at rear

Maximum static head

metres (feet)

45.7 (150)

Maximum pressure

bar (p.s.i.)

4.5 (65)

Gas inlet connection

Rc (in. BSP)

3/4 (3/4)

1 (1 )

Minimum dynamic gas

mbar gauge

15.0

16.2

15.0

pressure required at the boiler inlet in.w.g.

6.0

6.5

6.0

Electricity supply

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

Power Consumption

Watts

Nominal flue size (to BS. 835)

mm (in.)

152 (6)

Diverter outlet socket

154

internal diameter

1/16

Length of burner bars (overall)

377

497

617

737

14.8

19.5

24.3

29.0

Approx. dry weight

298

350

442

494

658

771

974

1090

Water contentm

litre

gal

6.2

8.0

9.5

11.2

Gas type

G20 I

20 mbar

Boiler

CXC 48

CXC 70

CXC 94

CXC 116

Number of sections

Boiler output High Rate

48.83

69.84

93.65

116.25

Condensing

Btu/h x 1000

166 600

238 300

319 500

396 600

Boiler output High Rate

44.63

63.84

85.6

106.3

Non-Condensing

Btu/h x 1000

152 300

217 800

292 100

362 700

Boiler Input

Gross

31.5

45.06

60.42

Low Rate

Btu/h x 1000

107 500

153 700

206 200

255 900

Nett

28.4

40.6

54.44

67.58

Btu/h x 1000

96 900

138 500

185 800

230 600

Boiler Input

Gross

52.5

75.1

100.7

125

Btu/h x 1000

179 100

256 200

343 600

426 500

High Rate

Nett

47.3

67.67

90.73

112.6

Btu/h x 1000

161 400

230 900

309600

384 200

Gas rate

4.4

7.0

9.4

11.6

172

247

331

411

Approx. flue gas 8.0% CO

& 60°C. m

/sec

0.023

0.033

0.045

0.056

volume (non condensing)
High rate

8.0% CO

& 140°F.

ft.

119

Manifold setting pressure

mbar

3.9

3.8

4.1

Low Rate

in.w.g.

1.6

1.5

1.6

Manifold setting pressure

mbar

11.7

11.8

10.7

11.5

High Rate

in.w.g.

4.7

4.3

4.6

Seasonal efficiency (SEDBUK)*

[85.8]%

[85.5]%

[86.2]%

[85.7]%

Electricity supply

230V, 50Hz, fuse 5A

Ignition

5 attempts followed by nonvolatile lockout.

Gas valve

High/Low and Off

Gas safety time

Maximum of 10 secs with 5 attempts with one min. between attempts.

Safety check

The control de-energises every 4 hours to check internal control functions.

Pump

Pump overrun operates if the flow temperature is greater than 75

Boiler thermostat

The boiler thermostat hysteresis is a maximum of 3

Table 3 - Boiler Control specification Maximum Flow Temperature 85

Table 2 - General Data

GENERAL

Table 1- Performance Data

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

)

*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 BGplc 0087.

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Boiler Size

Cold Feed

Open Vent

CXC 48 -70

3/4

CXC 94 -116

1/4

Sealed system filling point - refer to Frame 8

GENERAL

GAS CONTROLS

The gas controls consist of a high / low arrangement with direct
burner ignition.

ELECTRICAL CONTROLS

WARNING. The ON/STANDBY [1/0] button does NOT electrically
isolate the boiler.

The Concord CXC range incorporates an advanced
microprocessor based control system which operates all electrical
functions of the boiler including for operation, ignition, flame
detection, thermostatic control, and high/low operation. In addition,
the microprocessor has onboard servicing and commissioning
instructions and a fault diagnosis programme.

The illuminated LED display gives a continual read-out of the boiler
status and functions, but in the (unlikely) event of a fault condition,
will display the fault areas.

Combustion products are drawn through the boiler by a fan and
air flow is proved by a pressure switch.

The burner flame is ignited by a spark generator.

Blockage of the condensate drain is protected against by a float
switch situated in the sump.

OPTION KITS

Pressure Gauge Kit: A pressure gauge is available for the range
of boilers. Details for fitting are included with the pressure gauge.

Remote Indication Board (volt free): This provides the ability
for remote indication of lockout and overheat conditions.

Outside Sensor: This kit provides a sensor for temperature
compensation when the outside temperature changes. Each
boiler needs to be individually switched on therefore a sensor is
required per boiler.

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.

Flow and return connections are 2" BSP.

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 4.5 bar (65 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

The range of boilers is NOT suitable for:

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

SYSTEM DESIGN

The water efficiency of this range of boilers is higher than
conventional boilers, at any water temperature, because of the
increased heat exchanger area.

At return temperatures of 55 °C and below, the differences become
more marked because the water in the flue gases starts to
condense, releasing its latent heat. In general, the lower the return
temperature (down to its minimum temperature of 35 °C to protect
the primary heat exchanger) the better the boiler efficiency.

In new systems it is best to design for the lowest flow and return
temperatures that are practical (subject to the lower limit mentioned
above). Of course, the lower the mean water temperature the
greater must be the heating surface area.

PERFORMANCE

The efficiency of the Concord CXC range of boilers is related to
the return water temperature of the boiler. This graph shows that,
in order to achieve maximum efficiency at any given load, the
system controls should be used in a manner which maintains the
lowest return temperature commensurate with system performance

Graph 1 - Boiler efficiency

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GENERAL

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.

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 4 above.

However, for maintenance
purposes we suggest a
minimum rear clearance of
200mm.

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:

CXC 48 & 70

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

CXC 94 & 116

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

CLEARANCES & DIMENSIONS

Boiler Size

CXC 48

CXC 70

CXC 94

CXC 116

Front clearance

mm (in)

750 (29 1/2)

Rear clearance

mm (in)

200 (8) see text

Side clearance

mm (in)

50 (2)

100 (4)

Dimension A

mm (in)

723(28

1/2

)

846(33

5/16

) 969(38

1/8

)

1092(43)

Table 4

Graph 2 - Heat Load/ Water Volume

Graph 3 - Hydraulic Resistance

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GENERAL

3 OPEN VENTED SYSTEMS - Minimum static head requirements

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.

Table 5 - Flow rates for fully pumped systems

Boiler

Minimum flow rates for a

temperature difference of 35

C (63

l/s

g.p.m.

CXC 48

0.33

4.4

CXC 70

0.48

5.3

CXC 94

0.64

8.5

CXC 116

0.79

10.4

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 (C).

2. An independent cold feed/expansion pipe connection is made to

the redundant boiler return tapping ("D"). 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 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 ("B"). The final position
will depend upon the particular characteristics of the system.
Pumping over of water into the expansion cistern must be avoided.

and cost. Graph 1 is based on a 20°C temperature difference
across the boiler.

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 when the boiler switches off and until the flow temperature
is below 75

C and, in order to make use of this, the pump must be

wired to the appropriate terminal L

(pump) in the boiler control

box.

1. The minimum flow rate as given in Table 5 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 2.
Examples shown on Graph 2
a. For the CXC 116 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 CXC 94 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.

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 16, 17 and 18 illustrate
the control methods for achieving the above.

3. Pump selection should take account of the hydraulic

resistance given in Graph 3.

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.

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SEALED (PRESSURISED) SYSTEMS

automatic reset. In the event of shut down both visual and
audible alarms may be necessary.

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 is 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

GENERAL

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.

Aluminium Heat Exchanger

The secondary heat exchanger of the Concord CXC is made of
aluminium finned tube and so any water treatment must be
suitable for systems containing aluminium.

Under no circumstances should the boiler be fired before
the system has been thoroughly flushed.

Caradon Plumbing Limited recommend only the use of Fernox
or Betz Dearborn water treatment products, which must be used
in accordance with the manufacturers instructions. For further
information contact :-

Fernox Manufacturing. Co. Ltd, Tandem House, Marlowe Way,
Croydon, Surrey CRO 4XS, Tel 0870 5601 5000

Betz Dearborn Ltd, Widnes, Cheshire, Tel. 0151 424 5351

IMPORTANT: Any other treatment for this product will render
the guarantee of Caradon Plumbing Limited INVALID.

Notes.
1. If an inhibitor is used, and in hard water areas where treatment

to prevent lime deposits is necessary, it is most important that
the water treatment MUST be maintained at the correct
concentrations recommended by the treatment manufacturer.

Persons responsible for the continued operation of this boiler
should be made aware of this requirement.

If the boiler is installed in an existing system then any unsuitable
water additives MUST be thoroughly drained.

MINIMUM FLOW OF WATER - Refer to Table 5

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.

It is essential that the main pump and shunt pump both overrun
to dissipate the residual heat in the primary heat exchanger. This
is done automatically if:

a. An unswitched live supply is connected to the boiler control

box (for details see 'Electrical Connections').

b. The shunt pump (prewired) and main pump are connected to

the boiler control box (for details see 'Electrical Connections').

c. Part of the system is available to the main pump when the

call for heat by external controls is satisfied.

The boiler produces condensate when the system return water
temperature falls below 55 °C (the Dew Point of the combustion
products).

This condensate must be led away by a condensate drain
connected to the steel pipe at the rear of the boiler and installed
in accordance with IM22 (see 'Condensate Drain').

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%.

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

Working pressure 4.5 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

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GENERAL

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.

VENTILATION

Safe, efficient and trouble-free operation of conventionally 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 directly with the outside air is
required at both high and low levels. The minimum free areas of
these grilles must be according to the scale in Table 6.

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.

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 supplier
should be obtained.

FLUE SYSTEM DESIGN

The Concord CXC condensing boiler is supplied with an integral
fan which is fully matched to the boiler in each case to provide
correct combustion air flow.

The power of this fan is such that there is a large reserve of pressure
available to overcome a significant length of the flue without
affecting the combustion performance of the boiler. The pressure
available at the base of the flue to overcome flue resistance is
0.25 mbar (0.1 w.g.) This is sufficient to overcome the resistance
of approximately 30 metres of 150mm diameter smooth, straight
flue pipe.

Material

The type of flue pipe used should conform BS.715: Section 2
Stainless Steel or be of equivalent corrosion resistance. Advice
regarding the availability of proprietary types of flue system can
be obtained by contacting Caradon Plumbing Ltd. All joints or
connections in the flue system must be impervious to condensate
leakage and also any low points in the flue system should be
drained using pipe of material resistant to condensate corrosion.

Care should also be taken in the selection of flue terminals as
these tend to accentuate the formation of a plume.

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

INSTALLATION REQUIREMENTS

The appliance must be installed by a CORGI registered installer,
identified by . The installation of the boiler must be in accordance
with the relevant requirements of the Gas Safety Regulations, current
IEE (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 supplier, local authority and the relevant
British Standard Codes of practice and building regulations.

Limitations of Intended Operating Environment
These appliances are NOT suitable for installation where they will
be exposed to the elements.

A boiler room shall be constructed or adapted to meet the
requirements of BS. 6644.

The maximum ambient temperature is 32° C at 1.5 metres from
the floor, with a maximum humidity of 90% RH.

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: Control Heating by Low Pressure Hot Water.
CP342:2:

Centralised Hot Water Supply.

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

The appliance must be installed in a room separated from living
rooms and provided with appropriate ventilation direct to the outside
- see Table 6.

2. Artificially softened water must not be used in the system, under

any circumstances.

3. In all systems the fitting of a filter to the return pipework, in order

to prevent debris reaching the heat exchanger, is essential.

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

Table 6 - Ventilation Requirements
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).

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CONDENSATE DRAIN

The Concord CXC boiler will produce condensate whenever
the temperature of the return water from the system is below
approximately 55

C (the Dew Point of the combustion products).

Natural gas condensate is mildly acidic with a pH value of about
4 and therefore corrosion resistant materials must be used in the
construction of the condensate drain. Standard PVC pipe is
suitable for this purpose and should be connected to the steel
drain fitted on the boiler.

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 supplier should be requested. Installation pipework should

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be fitted and tested for gas soundness in accordance with BS.
6891 for small installations or IGE-UP-1 and IGE-UP-2 for large
installations.

The local gas supplier 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 see Frame 14.

CONCORD CXC BOILER ASSEMBLY - Exploded view

6. Float switch
7. Shunt pump.
8. End section.

Legend
1. Collector hood
2. Cleanout cover
3. Fan
4. Secondary heat exchanger
5. Air pressure switch.

9. Middle section.
10. Tie rods.
11. Base plate.
12. Combustion chamber.
13. Section bolt.

14. Front plate.
15. NOx duct.
16. Drain cock.
17. Burner manifold assy.
18. Gas cock.
19. Flueway baffles.
20. Thermostat pocket.

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Installation

1. Remove the jacket carton and outer packaging frame.

2. Remove the jacket pack support frame.

3. Remove the controls package and installation pack.

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

pack.

5. Remove 4 base bolts holding the 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 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 boiler forwards on the

packaging base and slide over the collapsing base on to
the floor.

Note.
Before manoeuvring the boiler into its final position see
Frame 8.

INSTALLATION

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PACKAGING

The Concord CXC boiler is despatched from the factory fully
assembled except for the casing, controls and installation
packs which are packed separately within the same wooden
crate as the boiler.

JACKET PACK contains

Lower front panel ................. 1 off

Upper front panel ................ 1 off.

Lower LH side panel ........... 1 off.

Lower RH side panel ........... 1 off.

Upper LH side panel ........... 1 off.

Upper RH side panel ........... 1 off.

Lower top panel .................. 1 off.

Upper top panel .................. 1 off.

Infill panel ............................ 1 off.

Support bracket ................... 2 off.

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

Jacket hardware pack ......... 1 off.

Lower rear panel ................. 1 off.

Upper rear panel ................. 1 off.

Upper middle rear panel ..... 1 off.

Lower middle rear panel ..... 1 off.

CONTROLS PACK contains

Controls box complete ....... 1 off

Controls installation pack ... 1 off

INSTALLATION PACK contains

R2 sq. hd. plug .................................... 3 off.

R2 installation pipe .............................. 2 off.

Installation & Servicing Instructions .... 1 off.

Users instructions ............................... 1 off.

System warning label ......................... 2 off.

PACKAGING AND BOILER REMOVAL

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Installation

Manoeuvring the boiler

1. Remove the gas cock to access the LHS tapping.

2. Screw the 2 handling bars (2" pipe supplied) into the 2

top tappings.

3. Screw in 2 bars (not supplied), 1 into the LH rear top

tapping and the second into the tee at the RH top
tapping.

4. Use these bars to manoeuvre the boiler into position.

5. Complete the system connections, using suitable

jointing compound, as follows:

a. The flow connection must be made to the upper

tapping on the primary heat exchanger.

10 FLUE CONNECTION

The 150mm (6") flue should conform to BS.715: Section 2
Stainless Steel or be of equivalent corrosion resistance.

The flue must be designed to have no greater resistance
than that of 30m of straight, smooth 150mm (6") pipe.

All joints must be impervious to condensate leakage.

The condensate drain must be 1

1/4

" diameter PVC pipe

from the pre-fitted drain at the rear of the boiler.

The condensate drain may be led directly into the normal
drainage system. The pipe should be installed with an
adequate slope (e.g. 1 in 50) and consideration should be
given to frost protection.

The drain should be in accordance with IM 22.

Connections to BS.5355 can be used directly, or
connections to BS.5354 may be used with a suitable
adaptor.

Note.
A condensate trap is built into the boiler sump therefore an
external trap is not necessary.

b. The return connection must be made to the upper

tapping on the secondary heat exchanger.

c. Complete the water connections by plugging the 2

front top and 1 rear top tappings with the 2" BSP
plugs provided. The remaining 1" lower tapping
should be plugged if not used for cold feed on an
open vent system or connection of a pressure
vessel, if on a sealed system.

3. Position the overheat thermostat phial into the LH side

thermostat pocket.

The illustration shows the rear of the boiler with the
flow and relative overheat thermostat position.

Ensure that the overheat thermostat phial is correctly
secured in the pocket. Refer to Frame 13.

BOILER ASSEMBLY AND SYSTEM CONNECTIONS

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CONDENSATE DRAIN CONNECTION

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Installation

11 GAS CONNECTION

1. Refit the gas cock.

2. Connect the gas supply to the gas pipe elbow.

The gas pipe should enter the boiler at the top LH side of
the boiler.

3. Table 2 gives details of the inlet connection size and the

minimum working pressures.

5. Fit clips to the top of each side panel.

6. Fit the spire clips to the side casing panels.

7. Hook on the control box to side panels.

8. Screw in self tapping screws at the bottom of the

control box to fix it to the side panels.
Push in the mains plug into the socket at the back
of the control box.

Unpack the control box from its carton and find the mains plug
strapped to the back of the box.

The boiler casing should now be fitted.

The jacket hardware pack contains all the screws required for assembly.
1. Fit support angles to the

collector hood and sump. The
angle with the hole for the
earth screw fits to the front.
Ensure the rear support angle
is fitted as shown.

2. Wire up the mains input cable

to the plug provided.
Run this cable along the lower
clips (using the cable ties in the hardware pack) of the LH side panel with
the plug placed at the front.

3. Slide bottom of lower side panels on to studs on base tray.
4. Screw lower side panel to support angles.

Repeat for other side.

INSTALLATION

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12 CASING ASSEMBLY

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Installation

10. Ensure that the Heyco bush is correctly located

and that the top of the bush is at the marked line.
Route the cables from the temperature probe, air
pressure switch and float switch through the clips
on the RH side panel.
Neatly coil up any excess length of cable and
push in the plug-in connector into the connection
box.

11. Hook the upper side panel into the keyhole slot.
12. Fix the upper side panel in position.

One screw into the lower side panel, one screw
into the upper support angle.
Repeat for the other side.

13. Clip in the upper top panel.

Fit the infill panel around the flue and secure
underneath top panel with the 2 self tapping
screws provided.

14. Fit earth leads as

shown.

9. Route the overheat thermostat capillary through the cable clips as

shown.
Ensure the phial is correctly seated in the correct pocket opposite
side to the flow connection - refer to Frame 8.
Secure with the split pin provided.

Complete the following after reaching Frame 32
15. Fit the lower top panel.

Fit the lower front panel.

16. The upper front panel has 2 hooks at the bottom.

Drop in these 2 hooks behind the back edge of the
lower top panel, push home onto the 4 catches and
secure with the top screw.

17. Fit rear panels in the sequence shown. Do NOT

tighten the screws until all panels are fitted.
Fit No.1 panel with the top 2 screws only.
Fit No.2 panel with the bottom 2 screws only.
Fit No.3 panel with the 4 screws engaging panels 1 and 2.
Fit No.4 panel with the 4 screws.

Align all panels and tighten all screws.

13 CASING ASSEMBLY - continued

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