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icos -

Installation & Servicing

GENERAL

Boiler Size

HE 12 Max HE 15 Max HE 18 Max HE 24 Max HE 12 Min HE 15-24 Min

Boiler input 'Q' =

Nett CV

12.2

15.1

18.7

24.4

9.8

9.1

Btu/h

41 600

51 500

63 800

83 300

33 400

31 000

Gross CV

13.5

16.8

20.7

27.1

10.9

10.1

Btu/h

46 000

57 200

70 800

92 500

37 200

34 400

Gas consumption

l/s (cu.ft/h) 0.35 (44.2) 0.43 (54.7) 0.53 (68.0) 0.70 (89.7) 0.28 (35.6) 0.26 (33.3)

Boiler output 'P' =

C Mean water

12.0

14.6

18.2

23.4

9.3

8.8

temperature

Btu/h

40 900

50 000

62 300

80,000

31 800

30,000

C Mean water

12.7

15.5

19.2

25.1

10.5

9.6

temperature

Btu/h

43 300

53 000

65 700

85 700

35 900

32 800

Seasonal efficiency (SEDBUK) *

Band A

[90.1]%

[90.4]%

[90.3]%

[90.2]%

NOx classification

Class 5

Boiler Size

HE 12, HE 15, HE 18, HE 24

Gas supply type and connection

2H-G20-20 mbar Rc

(

" BSP Female

)

Injector size

Stereomatic 5.6mm dia. (HE 12 5.8mm dia).

Flow connection

22mm copper

Return connection

22mm copper

Flue terminal diameter

mm (in.)

100 (4)

Maximum static water head

m (ft.)

30.5 (100)

Minimum static water head

m (ft.)

0.45 (1.5)

Electrical supply

230 V ~ 50 Hz

Boiler power consumption

38W

Fuse rating

External: 3A Internal: T3.15A L250 V

Water content

litre (gal.)

1.7 (0.37)

Packaged weight

kg (lb.)

38 (84)

Maximum installation weight

kg (lb.)

31 (68)

Boiler size

Height mm (in.)

582 (23)

Width mm (in.)

390 (15)

Depth mm (in.)

278 (11)

The value is used in the UK Government's Standard Assessment Procedure (SAP) for energy rating of dwellings.
The test data from which it has been calculated have been certified by a notified body.

CAUTION.

To avoid the possibility of injury during the installation, servicing or

cleaning of this appliance, care should be taken when handling edges of sheet steel
c

Note.
Gas consumption is calculated using a calorific value of
38.7 MJ/m

(1038 Btu/ft

) gross or 34.9 MJ/m

(935 Btu/ft

)

nett. To obtain the gas consumption at a different calorific
value:-

a. For l/s - divide the gross heat input (kW) by the gross

C.V. of the gas (MJ/m

)

b. For ft

/h - divide the gross heat input (Btu/h) by the

gross C.V. of the gas (Btu/ft

)

Key to symbols

GB = United Kingdom

IE = Ireland (Countries of destination)

PMS = Maximum operating pressure of water

= A room sealed appliance designed for connection via

ducts to a horizontal or vertical terminal which admits
fresh air to the burner and discharges the products of
combustion to the outside through orifices which, in this
case, are concentric. The fan is up stream of the
combustion chamber.

An appliance designed for use on 2nd Family gas, Group
H only.

Table 2 - Performance Data

Table 1 - Boiler Data

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icos -

Installation & Servicing

GENERAL

CONTENTS

Air Supply ....................................................................... 9
Benchmark Commissioning Checklist ..................... 50
Boiler Clearances ......................................................... 6
Boiler Exploded Diagram ............................................ 14
Electrical Connections ............................................... 23
Electrical Supply ........................................................... 9
Electrical Systems Diagrams .................................... 26
Extension Ducts - Fitting ............................................. 19
Fault Finding ................................................................. 41
Flow Wiring Diagram .................................................. 25
Flue Fitting .............................................................. 16-19
Flue Installation Requirements .................................... 8
Gas Safety Regulations ................................................ 7
Gas Supply ..................................................................... 8
Initial Lighting .............................................................. 27
Installation ............................................................. 14-28
Mandatory Requirements ............................................. 7
Safe Handling ................................................................ 7
Servicing ................................................................ 29-40
Short List of Parts ....................................................... 45
Terminal Guards ............................................................ 8
Thermostatic Radiator valves .................................... 9
Water and Systems ................................................ 9-13
Water Connections ................................................. 6, 23
Water Treatment ......................................................... 13
Wiring Diagrams ......................................................... 25

icos

Destination Countries:

GB, IE

oiler

Page

Make and model ....................................................... 5
Appliance serial no. on data badge ...................... 14
SEDBUK No. % ......................................................... 4

Controls

Time and temperature control to heating ............. 26
Time and temperature control to hot water .......... 26
Heating zone valves .............................................. n/a
TRV's ......................................................................... 9
Auto bypass .............................................................. 9
Boiler interlock .......................................................... 9

For all boilers

Flushing to BS.7593 .............................................. 13
Inhibitor .................................................................. 13

Central heating mode
Heat input ................................................to be calculated

For assistance see Technical Helpline on the back page

Page

Burner operating pressure .................................... n/a
Central heating flow temp. ...... measure and record
Central heating return temp. ... measure and record

For combination boilers only

Scale reducer ......................................................... n/a

Hot water mode

Heat input ............................................................... n/a
Max. operating burner pressure .............................. n/a
Max. operating water pressure ............................. n/a
Cold water inlet temp ............................................ n/a
Hot water outlet temp. ........................................... n/a
Water flow rate at max. setting .............................. n/a

For condensing boilers only

Condensate drain .................................................. 20

For all boilers: complete, sign & hand over to customer

For GB, to comply with Building Regulations Part L1 (Part J in Scotland) the boiler should be fitted in accordance with the
manufacturer's instructions. Self-certification that the boiler has been installed to comply with Building Regulations can be
demonstrated by completing and signing the Benchmark Commissioning Checklist.

Boiler size

G.C. Appliance No.

PI No.

Benchmark No.

HE12

41 397 95

0063 BO 3315

HE15

41 397 83

0063 BO 3315

HE18

41 397 84

0063 BO 3315

HE24

41 397 85

0063 BO 3315

Natural Gas only

BENCHMARK COMMISSIONING CHECKLIST DETAILS

NOTE TO THE INSTALLER: COMPLETE

THE BENCHMARK COMMISSIONING

CHECKLIST AND LEAVE THESE

INSTRUCTIONS WITH APPLIANCE

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Installation & Servicing

GENERAL

The boiler flow and return pipes are supplied fitted to the boiler
ready for top connection

Notes.

a. For the heating loads in excess of 60,000 Btu/h, 28mm (1") flow

and return pipes should be used to and from the boiler.

b. This appliance is NOT suitable for use with a direct hot water

cylinder.

BOILER WATER CONNECTIONS

BOILER CLEARANCES

all dimensions in mm (in.)

The following minimum clearances must be maintained for
operation and servicing.

Additional space will be required for installation, depending upon
site conditions.

Side and Rear Flue
a Provided that the flue hole is cut accurately, e.g. with a core drill,

the flue can be installed from inside the building where wall
thicknesses do not exceed 600mm (24"). Where the space into
which the boiler is going to be installed is less than the length of
flue required the flue must be fitted from the outside.

Installation from inside ONLY
b. If a core boring tool is to be used inside the building the space in

which the boiler is to be installed must be at least wide enough
to accommodate the tool.

Front clearance
The minimum front clearance when built in to a cupboard is
5mm (

1/4

") from the cupboard door but 450mm (17

3/4

overall clearance is still required, with the cupboard door
open, to allow for servicing.

N.B. The boiler will not fit into a standard depth wall unit. In

order for it to do so the plastic fascia should be removed. See
Frame 36.

Bottom clearance
after installation can be reduced to 5mm in an adequately
ventilated enclosed cupboard. However, 100mm must be
available for servicing.

SIDE FLUE ONLY

Horizontal length of flue

Top clearance

from centre line of boiler

required (MIN.)

to outside wall

Dim. A

0.5 m

165 mm (6

1/2

1.0 m

170 mm (6

11/16

)

1.5 m

185 mm (7 1

2.0 m

200 mm ( 7

7/8

2.5 m

210 mm (8 1

3.0 m

225 mm (8

7/8

3.5 m

235 mm (9

1/4

4.0 m

250 mm (10

7/8

4.5 m

260 mm (10

1/4

5.0 m

275 mm (10

13/16

5.5 m

290 mm (11

3/8

6.0 m

300 mm (11

13/16

REAR FLUE ONLY

MIN. Top clearance required = 145 mm (5

3/4

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Installation & Servicing

GENERAL

INTRODUCTION

The icos range of boilers are a fully automatically controlled,
wall mounted, low water content, balanced flue, fanned,
condensing gas boiler. It has full modulating central heating
outputs of :
HE12 9.3 kW (32,000 Btu/h) to 12.0 kW (41,000 Btu/h).
HE15 8.8 kW (30,000 Btu/h) to 14.7 kW (50,000 Btu/h).
HE18 8.8 kW (30,000 Btu/h) to 17.6 kW (60,000 Btu/h).
HE24 8.8 kW (30,000 Btu/h) to 23.4 kW (80,000 Btu/h).
Due to the high efficiency of the boiler a plume of water vapour
will form at the flue terminal during operation depending on
external conditions.
The boiler casing is of white painted mild steel with the user
controls capable of being mounted remotely from the boiler, if
the option is required.
The heat exchanger is of cast aluminium.
Note.
These boilers cannot be used on systems which include gravity
circulation.
The boilers are suitable for connection to fully pumped, open
vented or sealed water systems. Adequate arrangements for
completely draining the system by provision of drain cocks
MUST be provided in the installation pipework.

OPERATION

When there is a demand for heat, the heating system is
supplied at the selected temperature of between 30

C and

The boiler features a comprehensive diagnostic system which
gives detailed information on the boiler status when operating,
and performance of key components to aid commissioning and
fault finding.

SAFE HANDLING

This boiler may require 2 or more operatives to move it to its
installation site, remove it from its packaging base and during
movement into its installation location. Manoeuvring the boiler
may include the use of a sack truck and involve lifting, pushing
and pulling.
Caution should be exercised during these operations.
Operatives should be knowledgeable in handling techniques
when performing these tasks and the following precautions
should be considered:
·

Grip the boiler at the base.

Be physically capable.

Use PPE as appropriate, e.g. gloves, safety footwear.

During all manoeuvres and handling actions, every attempt
should be made to ensure the following unless unavoidable
and/or the weight is light.
·

Keep back straight.

Avoid twisting at the waist.

Avoid upper body/top heavy bending.

Always grip with the palm of the hand.

Use designated hand holds.

Keep load as close to the body as possible.

Always use assistance if required.

OPTIONAL EXTRA KITS

Flue Extension Ducts (1000mm long up to 6m)
Flue Finishing Kit
90

Elbow Kit (maximum 4 elbows per installation).

Roof Flue Kit (to a maximum of 8m)

Powered Vertical Flue Kit (to a maximum primary flue length
of 8m + a maximum secondary flue length of 6m)
Twin Flueing Kit (to a maximum of 46m combined total of
flue and air ducts)
Remote User Control Kit
Boiler Stand-off Kit
Siphon Kit

SAFETY

Current Gas Safety (Installation and Use) Regulations or
rules in force.
The appliance is suitable only for installation in GB and IE and
should be installed in accordance with the rules in force.
In GB, the installation must be carried out by a CORGI
Registered Installer. It must be carried out in accordance with
the relevant requirements of the:
·

Gas Safety (Installation and Use) Regulations

The appropriate Building Regulations either The Building
Regulations, The Building Regulations (Scotland), Building
Regulations (northern Ireland).

The Water Fittings Regulations or Water byelaws in
Scotland.

The Current I.E.E. Wiring Regulations.

Where no specific instructions are given, reference should be
made to the relevant British Standard Code of Practice.
In IE, the installation must be carried out by a Competent
Person and installed in accordance with the current edition of
I.S.813 "Domestic Gas Installations", the current Building
Regulations and reference should be made to the current ETCI
rules for electrical installation.
Detailed recommendations are contained in the following British
Standard Codes of Practice:
BS. 5440:1

Flues (for gas appliances of rated input not
exceeding 70 kW).

BS. 5440:2

Ventilation (for gas appliances of rated input not
exceeding 70 kW).

BS. 5449

Forced circulation hot water systems.

BS. 5546

Installation of gas hot water supplies for
domestic purposes (2nd Family Gases).

BS. 6798

Installation of gas fired hot water boilers of rated
input not exceeding 60 kW.

BS. 6891

Low pressure installation pipes.

Health & Safety Document No. 635
The Electricity at Work Regulations, 1989.
The manufacturer's notes must NOT be taken, in any way, as
overriding statutory obligations.
IMPORTANT. These appliances are CE certificated for safety
and performance. It is, therefore, important that no external
control devices, e.g. flue dampers, economisers etc., are
directly connected to these appliances unless covered by these
Installation and Servicing Instructions or as otherwise
recommended by Caradon Ideal Limited in writing. If in doubt
please enquire.
Any direct connection of a control device not approved by
Caradon Ideal Limited may invalidate the certification and the
normal appliance warranty. It could also infringe the Gas Safety
Regulations and the above regulations.

SAFE HANDLING OF SUBSTANCES

Care should be taken when handling the boiler insulation
panels, which can cause irritation to the skin. No asbestos,
mercury or CFCs are included in any part of the boiler or its
manufacture.

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Installation & Servicing

GENERAL

LOCATION OF BOILER

The boiler must be installed on a flat and vertical wall, capable
of adequately supporting the weight of the boiler and any
ancillary equipment.
The boiler may be fitted on a combustible wall and insulation
between the wall and the boiler is not necessary, unless
required by the local authority.
For electrical safety reasons there must be no access from the
back of the boiler.
The boiler must not be fitted outside.
Timber Framed Buildings
If the boiler is to be fitted in a timber framed building it should
be fitted in accordance with the Institute of Gas Engineering
document IGE/UP/7:1998.
Bathroom Installations
This appliance is rated IP20.
The boiler may be installed in any room or internal space,
although particular attention is drawn to the requirements of the
current IEE (BS.7671) Wiring Regulations and, in Scotland, the
electrical provisions of the building regulations applicable in
Scotland, with respect to the installation of the boiler in a room
or internal space containing a bath or shower. For Ireland
reference should be made to the current ETCI rules for
electrical installations and I.S.813:2002.
If the appliance is to be installed in a room containing a bath or
shower then, providing water jets are not going to be used for
cleaning purposes (as in communal baths/showers), the
appliance can be installed in Zone 3, as detailed in BS.7671.

Compartment Installations
A compartment used to enclose the boiler should be designed
and constructed specially for this purpose.
An existing cupboard or compartment may be used, provided
that it is modified for the purpose.
In both cases details of essential features of cupboard /
compartment design, including airing cupboard installation,
are to conform to the following:

BS. 6798. (No cupboard ventilation is required - see "Air
Supply" for details).
The position selected for installation MUST allow adequate
space for servicing in front of the boiler.
For the minimum clearances required for safety and
subsequent service see the wall mounting template and
Frame 2. In addition, sufficient space may be required to
allow lifting access to the wall mounting plate.

GAS SUPPLY

The local gas supplier should be consulted, at the installation
planning stage, in order to establish the availability of an
adequate supply of gas. An existing service pipe must NOT be
used without prior consultation with the local gas supplier.
The boiler MUST be installed on a gas supply with a governed
meter only.

A gas meter can only be connected by the local gas supplier or
by a CORGI registered engineer. In IE by a Competent Person.

An existing meter should be checked, preferably by the gas
supplier, to ensure that the meter is adequate to deal with the
rate of gas supply required.

N.B.

The principle of the 1:1 gas valve ensures that the icos

HE range is able to deliver it's full output at inlet pressures
down to 14mb. However if dynamic pressures below 20mb are
experienced ensure this is adequate for ALL other gas
appliances in the property.

IMPORTANT.
Installation pipes MUST be fitted in accordance with BS. 6891.
In IE refer to I.S.813:2002. Pipework from the meter to the boiler

MUST be of an adequate size, i.e. no longer than 20m and not
less than 15mm O.D.

The complete installation MUST be tested for gas soundness
and purged as described in the above code.

FLUE INSTALLATION

Pluming will occur at the terminal so terminal positions which
would cause a nuisance should be avoided.
The flue must be installed in accordance with the
recommendations of BS.5440-1:2000. In IE refer to I.S.813:2002.
The following notes are intended for general guidance.
1. The boiler MUST be installed so that the terminal is exposed

to external air.

2. It is important that the position of the terminal allows the free

passage of air across it at all times.

3. Minimum acceptable spacing from the terminal to

obstructions and ventilation openings are specified in Table 3.

4. Where the lowest part of the terminal is fitted less than 2m

(6'6") above a balcony, above ground or above a flat roof to
which people have access, then the terminal MUST be
protected by a purpose designed guard.

Ensure that the guard is fitted centrally.

Terminal guards are available from boiler suppliers. Ask for
TFC Flue Guard Model No. K6 (round plastic-coated). In
case of difficulty contact:

Grasslin (UK) Ltd.

Tel. +44(0) 01732 359 888

Tower House, Vale Rise

Fax. +44(0) 01732 354 445

Tonbridge. kent TN9 1TB

www.ffc.ukco.com

5. The flue assembly shall be so placed or shielded as to

prevent ignition or damage to any part of any building.

Flue Terminal Positions

Min. Spacing*

1. Directly below, above or alongside an opening

window, air vent or other ventilation opening.

300mm (12")

2. Below guttering, drain pipes or soil pipes.

25mm ( 1")*

BS5440-1 2000

75mm (3")

3. Below eaves.

25mm (1")*

BS5440-1 2000

200mm (8")

4. Below balconies or a car port roof.

25mm (1")*

BS5440-1 2000

200mm (8")

5. From vertical drain pipes or soil pipes.

25mm (1")*

BS5440-1 2000

150mm (6")

6. From an internal or external corner or to a

25mm (1")*

boundary along side the terminal.

BS5440-1 2000

300mm (12")

7. Above adjacent ground, roof or balcony level.

300mm (12")

8. From a surface or a boundary facing the terminal.

600mm (24")

9. From a terminal facing a terminal.

1,200mm (48")

10. From an opening in a car port

(e.g. door or window) into dwelling.

1,200mm (48")

11. Vertically from a terminal on the same wall.

1,500mm (60")

12. Horizontally from a terminal on the wall.

300mm (12")

Vertical Terminals

13. Above the roof pitch with roof slope of all angles. 300mm (12")

Above flat roof.

300mm (12")

14. From a single wall face.

600mm (24")

From corner walls.

1000mm (40")

Twin Flue Applications

15. Centre distance between air inlet and flue

outlet ducts.

120mm (5")

Table 3 - Balanced Flue Terminal Position

* Only one reduction down to 25mm is allowable per installation
otherwise BS5440-1 2000 dimensions must be followed.

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Installation & Servicing

GENERAL

Single feed, indirect cylinders are not recommended and MUST
NOT be used on sealed systems.

The appliances are NOT suitable for gravity central heating nor
are they suitable for the provision of gravity domestic hot water.

The hot water cylinder and ancillary pipework, not forming part
of the useful heating surface, should be lagged to prevent heat
loss and any possible freezing - particularly where pipes run
through roof spaces and ventilated underfloor spaces.

The boiler must be vented.

The hydraulic resistance of the boilers, at MAXIMUM OUTPUT,
with an 11

C (20

F) temperature differential, is shown in

Graph 1.

BOILER CONTROL INTERLOCKS

Caradon Ideal Limited recommend that heating systems
utilising full thermostatic radiator valve control of temperature in
individual rooms should also be fitted with a room thermostat
controlling the temperature in a space served by radiators not
fitted with such a valve as stated in BS. 5449.

Central heating systems controls should be installed to ensure
the boiler is switched off when there is no demand for heating
or hot water.

When thermostatic radiator valves are used, the space heating
temperature control over a living / dining area or hallway having
a heating requirement of at least 10% of the boiler heat output
should be achieved using a room thermostat, whilst other
rooms are individually controlled by thermostatic radiator
valves. However, if the system employs thermostatic radiator
valves on all radiators, or two port valves without end switches,
then a bypass circuit must be fitted with an automatic bypass
valve to ensure a flow of water should all valves be in the
closed position.

ELECTRICAL SUPPLY

WARNING.
This appliance must be earthed.

Wiring external to the appliance MUST be in accordance with
the current I.E.E. (BS.7671) Wiring Regulations and any local
regulations which apply. For Ireland reference should be made
to the current ETCI rules for electrical installations.

The point of connection to the mains should be readily
accessible and adjacent to the boiler.

CONDENSATE DRAIN -

Refer to Frames 23 & 44

A condensate drain is provided on the boiler. This drain must be
connected to a drainage point. All pipework and fittings in the
condensate drainage system MUST be made of plastic - no
other materials may be used.

IMPORTANT.

Any external runs must be insulated.

The drain outlet on the boiler is standard 21.5mm (

3/4

overflow pipe.

TERMINAL

The terminal assembly can be adapted to accommodate
various wall thicknesses. Refer to Frame 14.

AIR SUPPLY

It is NOT necessary to have a purpose-provided air vent in the
room or internal space in which the boiler is installed. Neither is
it necessary to ventilate a cupboard or compartment in which the
boiler is installed, due to the low surface temperatures of the
boiler casing during operation; therefore the requirements of BS
6798, Clause 12, and BS 5440:2 may be disregarded. In IE the
requirements of I.S.813:2002 may be disregarded.

WATER CIRCULATION SYSTEM

IMPORTANT.

A minimum length of 1 metre of copper pipe MUST be fitted to
both flow and return connections from the boiler before
connection to any plastic piping.

For the types of system and correct piping procedure see
Frames 1, and 3 to 8.

The central heating system should be in accordance with
BS.6798 and, in addition, for smallbore and microbore systems,
BS.5449.

WATER TREATMENT - see Frame 9

The hot water storage cylinder MUST be of the indirect type and
should preferably be manufactured of copper.

Pressure Drop Across Boiler

(metres w

ater)

0.5

1.0

Boiler Output (kW)

8.8

11.7

14.7

17.6

20.5

23.4

Ecl 1603

6. The air inlet/products outlet duct and the terminal of the

boiler MUST NOT be closer than 25mm (1") to combustible
material. Detailed recommendations on the protection of
combustible material are given in BS.5440-1:2000. In IE
refer to I.S.813:2002.

IMPORTANT

It is absolutely ESSENTIAL to ensure, in practice, that products
of combustion discharging from the terminal cannot re-enter the
building or any other adjacent building through ventilators,
windows, doors, other sources of natural air infiltration, or forced
ventilation / air conditioning.

If this should occur the appliance MUST be turned OFF, labelled
as 'unsafe' until corrective action can be taken.

Graph 1 - Water flow rate and pressure loss

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Installation & Servicing

GENERAL

OPEN VENT SYSTEM REQUIREMENTS

SCHEMATIC PIPEWORK AND SYSTEM BALANCING

The boiler does not normally need a bypass but at least some
radiators on the heating circuit, of load at least 10% of the
minimum boiler output, must be provided with twin lockshield
valves so that this minimum heating load is always available
(see footnote re. thermostatic radiator valves).

Return & flow
connections
load 30 - 60 = 22 mm
load 70 - 80 = 28 mm

Balancing

1. Set the programmer to ON for both CH

and HW. Turn the cylinder thermostat
down. Close the manual or thermostatic
valves on all radiators, leaving the twin
lockshield valves (on the radiators
referred to above) in the open position.
Turn up the room thermostat and adjust
these lockshield valves to give boiler flow
and return temperatures not more than
20

C apart. These valves should now be

left as set.

2. Open all manual or thermostatic radiator

valves and adjust the lockshield valves
on remaining radiators to give around
11

C temperature drop at each radiator.

3. Turn up the cylinder thermostat and

adjust the cylinder balancing valve so
that the cylinder achieves a maximum
flow consistent with adequate flow to the
radiators. Check that with only the
domestic hot water loop in circuit a
differential temperature of 20

C across

the boiler is not exceeded.

4. Adjust room and cylinder thermostats

and programmer to NORMAL settings.

The system should be vented directly off the boiler flow pipe, as
close to the boiler as possible. The cold feed entry should be
inverted and MUST be positioned between the pump and the vent,
and not more than 150mm (6") away from the vent connection.

Note. Combined feed and vent pipes may also be fitted.

There should be a minimum height 450mm (18") of open vent
above the cistern water level. If this is not possible refer to
Frame 5. The vertical distance between the highest point of the
system and the feed/expansion cistern water level MUST not be
less than 450 mm (18"). The pump must be fitted on the flow side of
the boiler.

A suitable pump is a domestic circulator capable of providing a
maximum 11

C (20

F) temperature differential across the boiler with the

whole of the heating circuit open (e.g. Grundfos UPS 15/50, 15/60 or
equivalent). With the minimum flow circuit allowed by the controls the
differential must not exceed 25

C. (18

C for the HE15)

The vertical distance between the pump and feed/expansion cistern
MUST comply with the pump manufacturer's minimum requirements, to
avoid cavitation. Should these conditions not apply either lower the
pump position or raise the cistern above the minimum requirement
specified by Caradon Ideal Limited. The isolation valves should be
fitted as close to the pump as possible.

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icos -

Installation & Servicing

GENERAL

Non-return

valve

Automatic

air vent

Hose unions

Additional

stop valve

Hose connector

Hosepipe

(disconnect

after filling)

Double check valve

assembly

(note direction of flow)

Temporary hose

(disconnect

after filling)

ecl6060

Note. The pump manufacturers' minimum requirements must be complied with.

LOW HEAD AND LARGE SYSTEMS WITH EXTENSIVE PIPE RUNS - OPEN VENT

All dimensions in mm (in.).
NB. Imperial dimensions are approximate

SEALED SYSTEM REQUIREMENTS

This arrangement is useful for large systems where
radiators at the extremities are difficult to vent. This can
lead to pumping over with conventional feed and vent
arrangements.

The following conditions MUST be observed:

1. The top of the automatic air vent must be below the

cold water level.

2. The static water level (cold) must be at least 200mm

above the top of the horizontal flow pipe, fitted as
shown. The vent connection MUST NOT be made
immediately off the top of the boiler as venting is
made less efficient.

3. The maximum practical length of 22mm cold feed pipe

should be used in order to reduce the effective volume
of hot system water expanding into the feed/expansion
cistern to a minimum.

a. A non-adjustable preset lift pressure not exceeding

3bar (45lb/in

b. A manual testing device.

c. Provision for connection of a discharge pipe.

The valve or discharge pipe should be positioned so
that the discharge of water or steam cannot create a
hazard to the occupants of the premises or cause
damage to electrical components and wiring.

3. Pressure Gauge

A pressure gauge covering at least the range 0-4 bar
(0-60 lb/in

) must be fitted to the system. The gauge

should be easily seen from the filling point and should
preferably be connected at the same point as the
expansion vessel.

Notes.
a. The method of filling, refilling, topping up or flushing

sealed primary hot water circuit from the mains via a
temporary hose connection is
only allowed if
acceptable to the
local water authority.

b. When installing the

filling device, it must be
connected as shown to
fully comply with the
water regulations. This
may involve the fitting of
an additional WRAS
approval isolator valve
to the mains supply.

1. General

a. The installation

must comply with the
requirements of BS. 6798
and BS. 5449.

b. The installation should be designed to work with

flow temperatures of up to 82

c. All components of the system, including the heat

exchanger of the indirect cylinder, must be
suitable for a working pressure of 3 bar (45lb/in

)

and temperature of 110

C. Care should be taken

in making all connections so that the risk of
leakage is minimised.

2. Safety Valve

A spring loaded safety valve complying with the
relevant requirements of BS. 6759 must be fitted in
the flow pipe as close to the boiler as possible and
with no intervening valve or restriction. The valve
should have the following features:

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icos -

Installation & Servicing

GENERAL

SEALED SYSTEM REQUIREMENTS - continued

pressure. The cold feed pipe from the cistern should
include a non-return valve and a stop valve with an
automatic air vent connected between them, the stop
valve being located between the system and the
automatic air vent. The stop valve may remain open
during normal operation of the system if automatic
water make-up is required.

b. Through a self-contained unit comprising a cistern,

pressure booster pump (if required) and, if necessary,
an automatic pressure reducing valve and flow
restrictor. The cistern should be supplied through a
temporary connection from a service pipe or cold
water distributing pipe.
This unit may remain permanently connected to the
heating system to provide limited automatic water
make-up. Where the temporary connection is supplied
from a service pipe or distributing pipe which also
supplies other draw-off points at a lower level then a
double check valve shall be installed upstream of the
draw-off point.

c. Through a temporary hose connection from a draw-off

tap supplied from a service pipe under mains
pressure. Where the mains pressure is excessive a
pressure reducing valve shall be used to facilitate
filling.

The following fittings shall form a permanent part of
the system and shall be fitted in the order stated:

A stop valve complying with the requirements of
BS. 1010, Part 2 (the hose from the draw-off tap shall
be connected to this fitting).
A test cock.
A double check valve of an approved type.

· Thoroughly flush out the whole of the system with

cold water, without the pump in position.

· With the pump fitted, fill and vent the system until the

pressure gauge registers 1.5 bar (21.5lb/in

Examine for leaks.

· Check the operation of the safety valve by manually

raising the water pressure until the valve lifts. This
should occur within ± 0.3 bar (± 4.3lb/in

) of the

preset lift pressure.

· Release water from the system until the initial system

design pressure is reached.

· Light the boiler and heat the system to the maximum

working temperature. Examine for leaks.

· Turn off the boiler and drain the system while still hot.

· Refill and vent the system.

· Adjust the initial pressure to the required value.

4. Expansion Vessel

a. A diaphragm type expansion vessel must be

connected to a point close to the inlet side of the
pump, the connecting pipe being not less than 15 mm
(

1/2

" nominal) size and not incorporating valves of

any sort.

b. The vessel capacity must be adequate to accept the

expansion of the system water when heated to
110

C (230

F).

c. The charge pressure must not be less than the

static water head above the vessel. The pressure
attained in the system when heated to 110

C (230

F) should be at least 0.35 bar (5 Ib/in

) less than the

lift pressure of the safety valve.
For guidance on vessel sizing refer to the table in
Frame 8.

For further details refer to BS. 5449, BS. 7074:1 and
the British Gas Corporation publication 'Material and
Installation Specifications for Domestic Central
Heating and Hot Water'. For IE refer to the current
edition of I.S.813.

5. Cylinder

The cylinder must be either of the indirect coil type or a
direct cylinder fitted with an immersion calorifier which is
suitable for operating on a gauge pressure of 0.35 bar
(5 Ib/in

) in excess of the safety valve setting. Single feed

indirect cylinders are not suitable for sealed systems.

6. Make-up Water

Provision must be made for replacing water loss from the
system, either:

a. From a manually filled make-up vessel with a readily

visible water level. The vessel should be mounted at
least 150 mm (6") above the highest point of the
system, and be connected through a non-return valve
to the system, fitted at least 300 mm (12") below the
make-up vessel on the return side of the domestic
hot water cylinder or radiators.
or

b. Where access to a make-up vessel would be difficult

by pre-pressurisation of the system. Refer to 'Filling',
below.

7. Mains Connection

There must be no direct connection to the mains water
supply or to the water storage tank supplying domestic
water, even through a non-return valve, without the
approval of the local water authority.

8. Filling

The system may be filled by one of the following

methods:

a. Through a cistern, used for no other purposes, via a

ball valve permanently connected directly to a service
pipe and/or a cold water distributing pipe.
The static head available from the cistern should be
adequate to provide the desired initial system design

Sizing procedure for expansion vessels: The volume of the expansion vessel (litres) fitted to a sealed system shall not be
less than that given by the table on the following page, multiplied by a factor of 0.8 (for flow temperatures of less than 83

C).

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