ideal Mini HE C24 User guide

installation and
servicing

mini HE

Your Ideal installation and servicing guide

For details of document amendments, refer to page 3

C24,C28

For users guide see reverse of book

When replacing any part of this appliance, use only spare parts that you can be assured
conform to safety and performance specification that we require. Do not use
reconditioned or copy parts that have not been clearly authorised by Ideal Boilers

17962.1138.1 0406 64A4 GB

*1796211381*

For the very latest copy of literature for specification purposes please visit our website
www.idealboilers.com where you will be able to download the relevant information in pdf format.

2

mini HE --- Installation & Servicing

DOCUMENT AMENDMENTS

Relevant Installation changes implemented in this book from Mod Level.............4905 to 0406

F Pages 33 and 37

Amendment to the illustration of the air pressure switch connection

Caradon Ideal Limited reserve the right to vary specification without notice

mini HE --- Installation & Servicing

3

GENERAL

Table 1 --- Boiler Data

mini HE C24 mini HE C28

Gas supply type & connection II

Inlet / Outlet connection --- Domestic Hot Water 15 mm copper

Flow & return connection --- Central Heating 22 mm copper

Flue terminal diameter mm (in.) 100 (4)

Max working pressure (sealed system) bar (lb/in2) 3.0 (43.5)

Max DHW water inlet pressure bar (lb/in2) 10.0 (145.0)

Min DHW water inlet pressure bar (lb/in2) 0.3 (4.4)

Electrical supply 230 Vac 50 Hz

Max power consumption W 140 150

External fuse rating 3 A

Internal fuse rating T 2A

Water content --- CH litre (gal.) 2.1 (0.46) 2.2 (0.48)

Water content --- DHW litre (gal.) 0.2 (0.044)

Dry weight kg (lb.) 42.5 (93.7) 44.5 (98.1)

Size: Height / Width / Depth mm (in.) 803 (31 5/8”) / 400 (15 3/4”) / 345 (13 9/16”)

Lift weight kg (lb.) 37.5 (82.7) 39.5 (87.1)

Table 2 --- Performance Data --- Central Heating

mini HE C24 mini HE C28

Max Min Max Min

Burner pressure (Hot) G20

G31

Input based on nett CV kW (btu/h) 25.0 (85 295) 11.0 (37 530) 29.0 (98 942) 13.0 (44 353)

Input based on gross CV kW (btu/h) 27.7 (94 516) 12.2 (41 628) 32.2 (109 871) 14.4 (49 135)

Output Non Condensing G20

G31

Output Condensing G20

G31

Gas consumption (Hot) G20

G31

Seasonal efficiency* G20

G31

NOx classification Class 2

mbar (in.w.g.) 10.8 (4.3)

kW (btu/h) 24.6 (83 973)

kW (btu/h) 26.6 (90 754)

l/s (ft3/h)
l/s

(SEDBUK) % Band B 87.7

35.5 (14.2)

23.7 (80 894)

26.6 (90 754)

0.74 (93.6)

0.30

Band B 86.9

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

Table 3 --- Performance Data --- Domestic Hot Water

mini HE C24 mini HE C28

Burner pressure (Hot) G20

G31

Input based on nett CV kW (btu/h) 25.0 (85 295) 29.0 (98 942)

Input based on gross CV kW (btu/h) 27.7 (94 516) 32.2 (109 871)

Output Non Condensing G20

G31

Output Condensing G20

G31

Gas consumption (Hot) G20

G31

Flow 35 ° C temp. rise l/m (gpm) 10.1 (2.2) 11.7 (2.6)

Domestic hot water specific rate l/m (gpm) 11.9 (2.6) 13.9 (3.1)

Note: the gas consumption is calculated using a calorific

mbar (in.w.g.) 10.8 (4.3)

kW (btu/h) 24.6 (83 973)

kW (btu/h) 26.6 (90 754)

l/s (ft3/h)
l/s

35.5 (14.2)

23.7 (80 894)

26.6 (90 754)

0.74 (93.6)

Key to Symbols:

value of 38.7 MJ/m3(1038 Btu/ft3) gross or 34.9 MJ/m3(935
Btu/ft3) nett.

To obtain the gas consumption at different calorific value: ---

a. FOR L/S --- divide the gross heat input (kW) by the gross
C.V. of the gas (MJ/m3)

b. FOR FT3/H --- divide the gross heat input (Btu/h) by the
gross C.V. of the gas (Btu/ft3)

IE = Ireland, GB = United Kingdom (Countries of destination)
PMS = Maximum operating pressure of water
C12C32C42= a room sealed appliance designed for
connection via concentric ducts to a horizontal or vertical
terminal or twin flue system.

II

H or 3rd family gas group 3P

G20 20mbar, G31 37mbar, 22 mm copper

2H3P

1.5 (0.6)

7.7 (3.1)

10.2 (34 936)

10.2 (34 936)

11.1 (37 871)

10.8 (36 997)

0.32 (40.9)

0.13

Maximum

0.30

= appliance designed for use on 2nd family gas group

2H3P

10.0 (4.0)

36.0 (14.4)

28.3 (96 488)

27.4 (93 599)

30.7 (104 602)

30.7 (104 602)

0.85 (108.4)

0.34

Band B 87.5
Band B 87.0

28.3 (96 488)

27.4 (93 599)

30.7 (104 602)

30.7 (104 602)

0.85 (108.4)

1.6 (0.6)

7.7 (3.1)

12.1 (41 284)

12.1 (41 284)

13.2 (44 965)

12.9 (44 016)

0.35 (45.2)

10.0 (4.0)

36.0 (14.4)

0.34

0.14

CAUTION. To avoid the possibility of injury during the installation, servicing or cleaning

of this appliance care should be taken handling edges of sheet steel components.

4

mini HE --- Installation & Servicing

GENERAL

mini HE

Boiler size G.C. appliance No. PI No.

(Benchmark No.)

mini HE C24 47 ---348 ---38 0694BP0384
mini HE C28 47 ---348 ---39 0694BP0384

Destination countries: GB, IE

CONTENTS

Air supply 9

Benchmark Commissioning Checklist 58

Boiler clearances 6

Boiler exploded view 14

Electrical connections 20

Electrical supply 10

Fault finding 48

Flow wiring diagram 24

Flue fitting 16

Gas conversion 29

Gas safety regulations 7

Gas supply 8

Installation 15

Mandatory requirements 7

Replacement of components 34

Safe handling 7

Servicing 30

Short list of parts 55

Thermostatic radiator valves 12

Water connections 19

Water treatment 9

Wiring diagrams 22

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.

BENCHMARK COMMISSIONING CHECKLIST DETAILS

Boiler 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 26

TRV’s 12

Auto bypass 12

Boiler interlock 12

For all boilers

Flushing to BS.7593 9

Inhibitor 9

Central heating mode

Heat input to be calculated

Boiler Page

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

For combination boilers only

Scale reducer 12
Hot water mode
Heat input to be calculated
Max. operating burner pressure measure and record
Max. operating water pressure measure and record
Cold water inlet temp measure and record
Hot water outlet temp. measure and record
Water flow rate at max. setting measure and record

For condensing boilers only

Condensate drain 20
For all boilers: complete, sign & hand over to customer
For assistance see Technical Helpline on the back page

NOTE TO THE INSTALLER: COMPLETE

THE BENCHMARK COMMISSIONING

CHECKLIST AND LEAVE THESE

INSTRUCTIONS WITH APPLIANCE

mini HE --- Installation & Servicing

5

GENERAL

1 BOILER WATER CONNECTION

400

31

50

35

803

700

257

16

Wall

mounting

Plate

Condensate

drain

connection

area

Pipe size O.D. mm

CH flow 22

CH return 22

Gas inlet 22

DHW cold inlet 15

DHW hot outlet 15

83 (3 1/4”)

52 (2”)

65 (2 9/16”)

CH flow

DHW hot outlet *

65 (2 9/16”)

64 (2 1/2”)

Gas inlet

CH return

DHW cold inlet *

2 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.

200 (7 7/8”)

25 (1”) 50 (2”)

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 thickness does not exceed 600 mm (24”).

Where the space into which the boiler is going to be installed
is less than the length of flue required the flue must be fitted
from the outside.

installation from inside ONLY

b. If a core boring tool is to be used inside the building the

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

273 (10 3/4”) 127 (5”)

190 (7 1/2”)

200 (7 7/8”)

Bottom clearance

The bottom clearance, after installation, can be reduced to
20mm. However, 200mm must be available for servicing.

Front clearance

The minimum front clearance when built into a cupboard is
50mm (2”) from the cupboard door. However 450mm
(17 3/4”) overall clearance is still required, with the cupboard
door open, to allow for servicing.

6

95 ()

mini HE --- Installation & Servicing

GENERAL

INTRODUCTION

mini HE C24 and mini HE C28 are wall mounted, low water

content, balanced flue, condensing combination gas boilers.

Central heating (CH) output and domestic hot water (DHW)
output are both fully modulating:

--- between 10.2 (34 936) and 24.6* (83 973) kW (btu/h) for

model mini HE C24;

--- between 12.1 (41 284) and 28.3* (96 488) kW (btu/h) for

model mini HE C28.

* ouputs with G31 (propane) feeding are sligthly different.
See section Boiler Data at page 4 for detailed figures.

Due to the high efficiency of the boiler a plume of water
vapour will form at the terminal during operation.

The boilers are suitable for connection to fully pumped,
pressurised sealed water systems ONLY.

A system bypass is not required when TRV’ s are fitted to all
radiators (see Frame 5). The boiler incorporates an automatic
bypass.

A circulating pump, pressure gauge, safety valve and heating
expansion vessel are provided.

The CH flow temperature is controlled by a thermistor. In
DHW mode the boiler modulates to sustain a nominal
adjustable water flow temperature of 55 ° C.

The boiler casing is of white painted mild steel with a
drop---down controls access door.

The boiler temperature control is located behind the control
panel door.

The main heat exchanger is made of copper.

The condensing heat exchanger (recuperator) and the DHW
heat exchanger are stainless steel.

The system pipework must include drain cocks in appropriate
places. Pipework may be taken downwards.

For upwards pipework installation an additional frame
(optional) must be used (see frame 18).

OPTIONAL EXTRA KITS

Programmer Kit fits neatly within the casing. Separate fitting
instructions are included with the kit. Note. If using an
alternative programmer read Frame 25 first.

Horizontal Concentric Extension Ducts

Up to 2,7 m (8’ 10”) for all models.

Other available kits are listed in frame 9.

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. Maneuvering 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:

F Grip the boiler at the base.
F Be physically capable.
F Use PPE as appropriate, e.g. gloves, safety footwear.

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

F Keep back straight.
F Avoid twisting at the waist.

mini HE --- Installation & Servicing

F Avoid upper body/top heavy bending.
F Always grip with the palm of the hand.
F Use designated hand holds.
F Keep load as dose to the body as possible.
F Always use assistance if required.

DHW OPERATION

With no call for CH the boiler fires only when DHW is drawn
off. When there is a call for CH, the heating system is supplied
at the selected temperature until DHW is drawn off. The
output is then directed by the diverter valve to heat the
secondary heat exchanger and supply a maximum draw--- off
of:

mini HE C24. 10.1 (2.2) l/min (gpm) at 35 degree rise.

mini HE C28 11.7 (2.6) l/min (gpm) at 35 degree rise.

The nominal DHW temperature is 55 ° C, but water drawn off
when the boiler has been on for central heating may be hotter
than this, for a short period of time.

GAS 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:

F Gas Safety (Installation and Use) Regulations
F The appropriate Building Regulations either The Building

Regulations, The Building Regulations (Scotland),
Building Regulations (Northern Ireland).

F The Water Fittings Regulations or Water byelaws in

Scotland.

F 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 6700 Design, installation testing and maintenance of

services supplying hot water for domestic use.

BS. 6798 Installation of gas fired hot water boilers of

rated input not exceeding 70 kW.

BS. 6891 Low pressure installation pipes.

Health & Safety Document No. 635.

The Electricity at Work Regulations, 1989.

The manufacturers 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

7

GENERAL

these Installation and Servicing Instructions or as otherwise
recommended by Caradon Ideal Ltd. in writing. If in doubt
please enquire.

Any direct connection of a control device not approved by
Caradon Ideal Ltd. could invalidate the certification and the
normal appliance warranty. It could also infringe the Gas
Safety Regulations and the above regulations.

SAFE HANDLING OF SUBSTANCES

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

LOCATION OF BOILER AND FLUE OUTLET

The boiler must be installed on a flat and vertical wall, capable
of adequately supporting the weight of the boiler and any
ancillary equipment.

The boiler may be fitted on a combustible wall and insulation
between the wall and the boiler is not necessary, unless
required by the local authority.

The boiler must not be fitted outside.

Timber Framed Buildings

If the boiler is to be fitted in a timber framed building it should
be fitted in accordance with the Institute of Gas Engineers
document IGE/UP/7, 1998.

Bathroom Installations

The boiler may be installed in any room or internal space,
although particular attention is drawn to the requirements of
the current I.E.E. (BS.7671) Wiring Regulations and, in
Scotland, the electrical provisions of the building regulations
applicable in Scotland with respect to the installation of the
boiler in a room or internal space containing a bath or shower.

For Ireland reference should be made to the current ETCI
rules for electrical installations and I.S.813:2002

Where a room sealed appliance is installed in a room
containing a bath or shower then the appliance and any
electrical switch or appliance control utilising mains electricity
should be so situated that it cannot be touched by a person
using the bath or shower.

Note. It is not permissible to install a mains socket in a
bathroom.

Where installation will be in an unusual location, special
procedures may be necessary and BS 6798 gives detailed
guidance on this aspect.

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 air cupboard installation, are
to conform to the following:

F BS 6798 (No cupboard ventilation is required --- see “Air

supply” for details)

F The position selected for installation MUST allow

adequate space for servicing in front of the boiler.

F 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.

8

GAS SUPPLY

The local gas supplier should be consulted, at the installation
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.
Natural gas boilers must be installed on a gas supply with a
governed meter. A gas meter can only be connected by the
local gas supplier or by a registered CORGI engineer.

Propane gas boilers MUST be installed with pipes, cylinders
and pressure regulators fitted in accordance with BS.5482.1.
Bulk tank installations MUST comply with the Home Office
code of practice for storage of liquefied petroleum gas at fixed
installations. The complete installation MUST be tested for
gas soundness and purged as described in the above code.

The boiler is adjusted at the factory for use with the relevant
supply gas. A working gas pressure equal to that stated in
Table 1 MUST be available at the boiler inlet.

Where applicable, the appliance can be converted for
G20--- Natural Gas or G31--- Propane Gas by using the
appropriate conversion kit.

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. not less than 22 mm O.D. copper or 3/4”
BSP iron.

FLUE INSTALLATION REQUIREMENTS

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 4.

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.

5 Where the terminal is fitted within 850mm (34”) of a plastic

or painted gutter or 450mm (18”) of painted eaves then an
aluminium shield at least 750mm (30”) long should be
fitted to the underside of the gutter or painted surface
fitted centrally above the flue.

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

boiler MUST NOT be closer than 25mm (1”) to
combustible material. Detailed recommendations on the
protection of combustible material are given in BS.
5440--- 1:2000. In IE refer to I.S. 813.2002.

Table 4 --- Balanced flue terminal position

Terminal position

1 Directly below, above or along side

of an openable window, air vent or
other ventilation opening

2 Below guttering, drain pipes or soil

pipes

3 Below eaves 25 mm ( 1”)

4 Below balconies or a car port roof 25 mm ( 1”)

5 From vertical drain pipes or soil

pipes*

6 From an internal or external corner

or to a boundary along side the
terminal

Minimum spacing

300 mm (12”)

25 mm ( 1”)

25 mm ( 1”)

25 mm ( 1”)

mini HE --- Installation & Servicing

GENERAL

7 Above adjacent ground, roof or

balcony level

8 From a surface or a boundary

facing the terminal.

9 From a terminal facing a terminal 1200 mm (48”)

10 From an opening in a car port (e.g.

door or window) into dwelling

11 Vertically from a terminal on the

same wall

12 Horizontally from a terminal on the

wall

* If the terminal is within 150mm of any vertical soil or drain
pipe, an aluminium shield at least 400mm (15 3/4”) long
should be fitted equi--- distant from the terminal and close to
the pipe.

Vertical Terminals

13 Above the roof pitch with roof

slope of all angles.

Above flat roof

14 From single wall face

From corner wall faces

Twin Flue Applications

15 Centre distance between air inlet

and flue outlet ducts

** Where the twin flue ducts are positioned at or near the above
minimum centres the wall sealing gaskets should be trimmed to
allow them to fit flat to the wall. This should be done for both in­side and outside wall gaskets

Terminals guards are available from boiler suppliers --- ask for
Tower Flue Guard, Model K6. In case of difficulty seek advice
from:

Grasslin UK Ltd.,Tower house, Vale Rise, Tonbridge,
Kent TN9 1TB Tel. [phone] Fax No. +44 (0)
1732 354 455 www.tfc--- group.co.uk

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 taken.

300 mm (12”)

600 mm (24”)

1200 mm (48”)

1500 mm (60”)

300 mm (12”)

300 mm (12”)

300 mm (12”)

600 mm (24”)

1000 mm (40”)

120mm (5”) **

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 BS6798, Clause 12, BS 5440:2
and in IE I.S. 813:2002 may be disregarded.

WATER CIRCULATION SYSTEM

The boilers are designed for connection to pressurised, fully
pumped, sealed water central heating systems ONLY. The
domestic hot water (DHW) calorifier is incorporated within the
combi boiler and only requires connection to the mains water
supply.

Additional Pumps.

The boiler is supplied with an integral circulating pump. If the
boiler is to be used in conjunction with any additional
circulating pumps, please contact the Technical Helpline for
advice on application.

IMPORTANT

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

Ensure that the mains water supply pressure is adequate to
provide the required DHW flow rate. Refer to Table 1 on
page 4.

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

The domestic hot water system should be in accordance with
BS. 5546 and BS. 6700.

Copper tubing to BS 2871:1 is recommended for water
carrying pipework and MUST be used for pipework carrying
potable water.

Any soldered joints on potable water pipework MUST NOT be
made with solder containing lead.

Ancillary pipework not forming part of the useful heating
surface should be lagged to prevent heat loss and any
possible freezing --- particularly where pipes run through roof
spaces or ventilated underfloor spaces.

Draining taps should be at least 1/2” BSP nominal size and
be in accordance with BS 2879.

WATER TREATMENT

Central Heating

Antifreeze fluid, corrosion and scale inhibitor fluids suitable for
use with boilers having copper heat exchangers may be used
in the central heating system.

IMPORTANT

The application of any other treatment to this product
may render the guarantee of Caradon Ideal Limited
INVALID.

Caradon Ideal Limited recommend Water Treatment in
accordance with the Benchmark Guidance Notes on Water
Treatment in Central Heating Systems.

Caradon Ideal Limited recommend the use of Fernox, GE
Betz Sentinel or Salamander water treatment products, which
must be used in accordance with the manufacturers
instructions.

Notes.

1. It is most important that the correct concentration of the
water treatment products is maintained in accordance with
the manufacturers’ instructions.

2. If the boiler is installed in an existing system any unsuitable
additives MUST be removed by thorough cleansing.
BS 7593:1992 details the steps necessary to clean a
domestic heating system.

3. In hard water areas, treatment to prevent lime scale may be
necessary --- however, the use of artificially softened water is
NOT permitted.

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

mini HE --- Installation & Servicing

9

GENERAL

Domestic Hot Water

In hard water areas where mains water can exceed 200ppm
Total Hardness (as defined by BS 7593:1993 Table 2) a scale
reducing device should be fitted into the boiler cold supply
within the requirements of the local water company. The use
of artificially softened water, however, is NOT permitted.

Caradon Ideal Limited recommend the use of Fernox
Qantomat, GE Betz Sentinel Combiguard and Calmag
CalPhos I scale reducing devices, which must be used in
accordance with the manufacturers’ instructions.

For further information contact:

3 ELECTRICAL SUPPLY

Warning. This appliance must be efficiently earthed.

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

Fernox
Cookson Electronics
Forsyth Road
Sheerwater
Woking
Surrey
GU21 5RZ
[phone]

Salamander (Eng) Ltd
Reddicap Trading Estate
Sutton Coldfield
West Midlands
B75 7BY

[phone]

The point of connection to the mains should be readily
accessible and adjacent to the boiler, except for bathroom
installations where the point of connection to the mains MUST
be situated outside of the bathroom.

Note. Where a room sealed appliance is installed in a room
containing a bath or shower then the appliance and any
electrical switch or appliance control utilising mains
electricity should be so situated that it cannot be touched by
a person using the bath or shower.

Calmag Ltd.
Unit 4---6 Crown Works
Bradford Road
Sandbeds
Keighley
West Yorkshire
BD20 5LN
[phone]

GE Betz
Sentinel Division
Foundry Lane
Widnes
Cheshire
WA8 8UD

[phone]

4 SEALED SYSTEM REQUIREMENTS

Central Heating

Note. mini HE boilers are suitable for fully pumped
pressurised sealed systems only.

REQUIREMENTS

1 General

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

2 Flow Temperature

The installation should be designed to work with flow
temperatures of up to 90 °C.

3 Working Pressure

All components of the system must be suitable for a working
pressure of 3 bar (45 lb/in2) and temperature of 110 ° C. Extra
care should be taken in making all connections so that the
risk of leakage is minimised.

The following components are incorporated within the
appliance:

a. Circulating pump.

b. Safety valve; with a non--- adjustable pre--- set lift pressure of
3 bar (45lb/in2).

c. Pressure gauge; covering a range of 0--- 4 bar.

d. 6 litre expansion vessel; with an initial charge pressure of

0.7 bar (10.5 lb/in2).

For further details refer to BS.5449:1 and the British Gas
Corporation publication ’Specifications for Domestic Central
Heating and Hot Water’.

10

4 Filling the system

Fill the system 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.

When installing the filling connection provided with the boiler
an additional WRAS approved valve must be fitted to the
mains water supply upstream of the double check valve to
fully comply the Water Regulations

Stop valve Additional stop valve

CH return

Temporary hose
(disconnect
after filling)

System filling and make ---up

Proceed with the following:

F Thoroughly flush out the whole of the system with cold

water before fitting the boiler.

F Fill and vent the system until the pressure gauge registers

1.5 bar (22 lb/in2). Examine for leaks.

F Release water from the system until a pressure of 1 bar

(15 lb/in2) is reached.

To avoid getting debris on the valve seat, do not use
the safety valve to do this.

F Light the boiler and heat the system to the maximum

working temperature. Examine for leaks.

F Turn off the boiler and drain the system while still hot.
F Refill and vent the system.
F Re --- pressurise the system to the desired charge pressure

(see Table 5).

Hose unions

Mains
Water
Supply

Double check valve
assembly
Note direction of flow

mini HE --- Installation & Servicing

GENERAL

mH2

O

Table 5

System charge pressure
(bar)

Safety valve setting 3.0

Vessel pre--- charge pressure
(bar)

System volume (litres) Volume of expansion vessel

75 --- --- ---

100 0.3 0.8 1.4

125 1.8 2.5 3.2

150 3.4 4.2 5.0

175 5.0 6.0 7.0

200 6.5 7.6 8.7

225 8.1 9.3 10.6

250 9.6 11.1 12.4

275 11.2 12.8 14.3

300 12.8 14.5 16.1

Multiply this factor by
system volume and deduct
6 litres to obtain size of
additional vessel for other
system volumes.

0.5 0.7 1.0

0.7

in addition to 6 litre unit

fitted to boiler

0.063 0.069 0.074

5 Size of expansion vessel

For the system water expansion to be contained by the 6 litre
expansion vessel the cold system volume must not exceed:

96 litres when pressurised to 0.5 bar (cold)

88 litres when pressurised to 0.7 bar (cold)

81 litres when pressurised to 1.0 bar (cold)

If the pressure exceeds 2.65 bar when the boiler is up to
temperature with all radiators in use then an additional
expansion vessel MUST be installed on the return pipework.

For expansion volumes see Table 5.

Guidance on vessel sizing is given in BS 7074:1 and BS 5449

For IE refer to the current edition of I.S. 813.

6 Hydraulic Loss
Remaining pump capacity

6

5

4

3

2

1

0

0 200 400 600 800 1000 1200 1400

Flow rate l/hour

7 Draining the system

Draining taps MUST be located in accessible positions to
permit the draining of the whole central heating system,
including the central heating side of the boiler. The taps
should be at least 1/2” BSP nominal size and be in
accordance with BS 2879.

mini HE --- Installation & Servicing

11

GENERAL

5 BOILER CONTROL INTERLOCKS

Thermostatic radiator valves.

Caradon Ideal Ltd. support the recommendations made by

leading manufacturers of domestic heating controls 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 BS5449. Such an arrangement will provide for a
more efficient control of the environment and will also avoid
the continuous running of the circulation pump during
programmed heating ON periods, saving electrical energy.

It is therefore strongly recommended that, when thermostatic
radiator valves are used, the space heating temperature
control over a living/dining area or a hallway, having a heat
requirement of at least 10% of the boiler output, is achieved
using a room thermostat whilst other rooms are individually
controlled by thermostatic radiator valves as stated in
BS5449.

6 DOMESTIC HOT WATER

REQUIREMENTS

1 The domestic hot water service must be in accordance

with BS 5546 and BS 6700.

2 For the minimum and maximum working pressures of the

mini HE C24 and mini HE C28 domestic hot water circuit
refer to Table 1, page 4.

3 The cold water supply pipe should be flushed before

fitting the boiler.

4 The boilers are suitable for connection to most types of

washing machine and dishwashing appliances.

For further information refer to “Good Practise Guide 143” a
publication of the energy efficiency office, available from the
building research establishment Garston Watford WD2 7JR
tel: [phone]

The boiler is fitted with an automatic internal bypass. No
further system bypass is required.

Typical installation

TRV

TRV

TRV

A

D

5 When connecting to suitable showers, i.e. those designed

for modulating domestic hot water, ensure that:

a. The cold inlet to the boiler is fitted with an approved

anti---vacuum or syphon non--- return valve.

b. Hot and cold supplies are of equal pressure.

6 Hard water areas

In areas where the water is ’hard’ it is recommended that
a proprietary scale---reducing device is fitted into the boiler
cold supply, within the requirements of the local water
company.

Room
T/stat

B

Balancing valve

12

mini HE --- Installation & Servicing

GENERAL

7 BOILER WATER CIRCUIT DIAGRAM

35

34

23

21

20

19

18

36

37

15

16

13

26

14

12

10

6

11

17

1 Domestic hot water (DHW) heat exchanger
2 Domestic hot water (DHW) flow switch

3 Domestic hot water (DHW) outlet pipe

4 Domestic cold water inlet cock

5 Three ---way diverter valve
6 Main circuit drainage cock

24

25

22

27

1

33

28

29

30

31

8

9

5

2

7

7 Central heating flow cock
8 By ---pass valve
9 Central heating (CH) return cock
10 3 bar pressure relief valve
11 Gas cock
12 Expansion vessel
13 Gas valve inlet pressure tap
14 Modulating gas valve
15 Burner pressure tap
16 Flame detection electrode
17 Ignition electrodes
18 Burner
19 Combustion chamber
20 Primary heat exchanger
21 Fan
22 Air pressure switch
23 Venturi device
24 Flue outlet pipe
25 Air intake pipe
26 Automatic air vent
27 Overheat thermostat

32

28 Pump
29 Pump vent plug

34

30 Water circuit temperature probe
31 CH flow switch
32 DHW temperature probe
33 CH circuit temperature/pressure gauge
34 Recuperator
35 Flue thermostat
36 Condensate trap
37 Condensate drain pipe

mini HE --- Installation & Servicing

13

8 BOILER ASSEMBLY ---

Exploded View

39

INSTALLATION

38

37

36

40

41

INSTALLATION

1

2

3

4

5

6

35

34

33

32

31

30

29

28

27

26

25

24

7

8

9
10
11

12

13

14

15

16

23 21

1 Air pressure switch

2 Recuperator

3 Condensate trap

4 Overheat thermostat

5 Condensing to main heat

exchanger connection pipe

6 Primary heat exchanger

7 Inner case cover

8 Flame detection electrode

9 Ignition electrodes

10 Heat exchanger return pipe

11 Auto air vent

12 Main circuit drainage cock

13 Pump

14

20

1922

14 DHW flow switch

15 DHW Thermistor

16 Ignition pcb

17 Right hand panel

18 Boiler front panel

19 Appliance data badge (inside)

20 Left hand panel

21 CH circuit pressure gauge

22 Model identification & instructions

23 Control panel door

24 Main control pcb

25 CH Thermistor

26 CH flow switch

27 Heat exchanger flow pipe

18

17

28 Return manifold

29 3 way diverter valve

30 DHW heat exchanger

31 Bypass pipe

32 3 bar pressure relief valve

33 Gas valve

34 Gas valve outlet pipe

35 Injector manifold

36 Burner

37 Flue hood

38 Fan

39 Expansion vessel

40 Venturi

41 Flue thermostst

mini HE --- Installation & Servicing

INSTALLATION

9 UNPACKING

The boiler is supplied fully assembled in one pack A, together
with a standard flue assembly for lengths up to 960 mm
(37” 3/4), rear or side flue outlet, in pack B.

Unpack and check the contents.

Pack A contents

A The boiler.

B Hardware pack

C Wall mounting plate

D Wall mounting template

E User’s, Installation & Servicing instructions.

F Filling loop assembly

A

B

E

Hardware pack contents

F 22 mm CH connection pipe --- 2 off.
F 22 mm Gas supply connection pipe --- 1 off.
F 15 mm DHW cold inlet connection pipe --- 1 off.
F 15 mm DHW hot outlet connection pipe --- 1 off.
F 1/2” connection nut --- 2 off.
F 1/2” sealing washer --- 3 off.
F 3/4” sealing washer --- 6 off.
F 3/4” Gas supply isolating valve --- 1 off.
F 3/4” CH circuit isolating valve --- 2 off.
F 1/2” DHW cold inlet isolating valve --- 1 off.

Pack B contents

G Air intake pipe ø 100 mm (4”), flue pipe ø 60 mm (2” 3/8)

with terminal grille assembly

D

C

F

H Centring spring

I Turret--- air pipe gasket

J Flue pipe gasket

K Boiler--- turret gasket

L Flue turret

M Self tapping screws 4,8x13 --- 4 off

N Wall finishing gasket --- internal (plastic)

O Wall finishing gasket --- external (rubber)

O

N

M

G

L

H

I

K

Optional extras, if ordered, are available in separate boxes.

F Electronic programmer kits --- 24 hrs & 7 day
F Extension duct kit pack D (ø 60/100)
F Flue support kits ø 80, 100, 125
F Vertical outlet flue kit with elbow (ø 60/100)
F 90° Elbow kit (ø 60/100)
F 45° Elbow kit (ø 60/100)
F Roof flue kit (ø 80/125)
F Universal weather collar (for roof flue kit)
F Flat roof weather collar (for roof flue kit)
F Extension duct kit (ø 80/125)
F 90° Elbow kit (ø 80/125)
F 45° Elbow kit (ø 80/125)
F Condense drain vertical (ø 80/125)
F Twin pipe kit (ø 80) with air and flue terminals
F Extension duct kit (ø 80)
F 90° Elbow kit (ø 80) male---female
F 45° Elbow kit (ø 80) male---female
F Vertical condense drain (ø 80)
F Horizontal condense drain (ø 80)
F Condense trap
F Stand--- off bracket
F Natural gas to LPG conversion kit
F LPG to natural gas conversion kit
F Condensate pump kit

J

INSTALLATION

10 PACKAGING

To unpack the boiler refer to the instructions on carton end
flap.

mini HE --- Installation & Servicing

15

INSTALLATION

11 FITTING THE FLUE SYSTEM

The minimum and maximum equivalent length for
co---axial pipes ø 60 ---100 and ø 80 ---125 mm are given in
Table 6.

The minimum and maximum equivalent length for ø 80
mm twin pipe systems are given inTable 7.

For roof flue systems having a flue length greater than
3m and all twin pipe systems, a condensate drain kit
must be fitted at the lowest point in the system. See the
list of optional extras (frame 9) for available drain kits.

Refer to the assembly instructions contained within the
chosen flue kit packaging for the correct assembly and

INSTALLATION

installation.

The horizontal sections of flue pipes must have a slope
not less than 1.5 deg. (25 mm per metre) towards the
boiler.

In the flue kit of pack B the flue pipe is angled within the air
duct therefore the air duct must be horizontally installed.

In the case that one or more extensions need to be used they
must be adequately supported so that there is no sag in the
flue pipe and a minimum fall of 1.5 deg. (25 mm per metre)
over the whole length towards the boiler is ensured.

Horizontal Concentric

Air duct

Rear Outlet Wall thickness + 125 mm

Rear outlet+Stand--- off Wall thickness + 160 mm

Side Outlet --- RH Wall thickness + Gap +62 mm

Side Outlet --- LH Wall thickness + Gap +208 mm

Twin pipe flue kits

For calculation of total flue length, the distance MUST be
measured from the centreline of the flue duct/air duct
connection to the end of the flue outlet grille/air inlet duct.

For each additional 45° M&F and 90° M&F flue bend used,
the maximum permissible length of flue system must be
reduced by 0,9m or 1,65m respectively.

Two restrictors with different sizes are supplied with the twin
pipe kit and have to be installed between the boiler and the
air intake adapter as indicated in the following picture.

The restrictor to be used and the lengths of allowable
equivalent flue outlet / air inlet ducts are indicated in Table 7
and in the following graph.

The restrictor size is marked on its body.

Air intake adapte r

Table 6

Minimum Maximum

Co---axial 60---100 0.3 (11.8”) 2.7 (8’ 10”)

Co---axial 80---125 0.5 (19.7”) 8.5 (27’ 10”)

Co---axial Flue kits.

Horizontal.
For calculation of total flue length, the distance MUST be
measured from the centreline of the concentric elbow to the
end of the terminal.

Vertical outlet
For calculation of total flue length, the distance MUST be
measured from the centreline of the outlet connector at the
boiler top panel to the end of the terminal grille.

For each additional 45° and 90° flue bend used, the
maximum permissible length of flue system must be reduced
by 1 m or 1,5 m respectively.

Cutting lengths of flue and air ducts

Measure the wall thickness and, when using a side outlet, the
gap between the inner wall and the boiler side casing.
Use the following chart to calculate the cutting length of air
duct.

Mark the air duct making reference on the groove.

Cut the flue duct at the same level of the air duct edge.

Cut this end

Groove

Restrictor

Gasket

Table 7

Equivalent pipe length

Restrictor

(air duct + flue duct)

Between 1 (39“) and 15 m (49’ 2”) ø 50 mm

More than 15 m (49’ 2”) up to 30 m (98’ 5”) ø 55 mm

Flue exhaust ”a”

32

30

28

26

24

22

20

18

16

14

12

10

8

6

Restrictor

4

50 mm

2

0

0 2 4 6 8 10 12 14 16 18 20 22 24 26 2 8 30 32

Restrictor

55 mm

Allowed values

Air intake ”b”

16

mini HE --- Installation & Servicing

INSTALLATION

Cutting lengths of flue and air ducts

Measure the wall thickness and, when using a side outlet, the
gap between the inner wall and the boiler side casing. Use
the following chart to calculate the cutting lengths of both flue
and air ducts.

Mark the air duct and flue duct making reference on the
groove.

Groove

Groove

12 REAR FLUE ASSEMBLY

Legend

1 Wall finishing gasket --- external (rubber)
2 Self tapping screw 4,2x13
3 Flue turret
4 Boiler --- turret gasket
5 Flue pipe gasket
6 Turret--- air pipe gasket
7 Centring spring
8 Air/flue pipe with terminal grille assembly
9 Wall finishing gasket --- internal (plastic)

Twin Pipe

Air duct

Rear Outlet Wall thickness + 130 mm

Rear outlet+Stand--- off Wall thickness + 165 mm

Side Outlet --- RH Wall thickness + Gap + 187 mm

Side Outlet --- LH Wall thickness + Gap + 93 mm

Flue Duct

Rear Outlet Wall thickness + 130 mm

Rear outlet+Stand--- off Wall thickness + 165 mm

Side Outlet --- RH Wall thickness + Gap +67 mm

Side Outlet --- LH Wall thickness + Gap + 213 mm

1

2

9

8

7

6

5

3

4

INSTALLATION

13 WALL MOUNTING TEMPLATE

(rear flue)

IMPORTANT

Detailed installation steps are given directly on the wall
mounting template

1 Tape the template into the selected position.
2 Ensure squareness by hanging a plumbine.
3 Mark onto the wall the following:

a. the wall mounting plate screw positions
b. the position of the flue duct.

(Mark the centre of the hole as well as the circumference)

4 Remove the template from the wall

mini HE --- Installation & Servicing

b

a

17

INSTALLATION

14 WALL MOUNTING TEMPLATE

(side flue)

IMPORTANT

Detailed installation steps are given directly on the wall
mounting template

1 Tape the template into the selected position.

2 Ensure squareness by hanging a plumbine.

3 Mark onto the wall the following:

a. the wall mounting plate screw position
b. Extended the centre line as shown.

Mark the flue ductcentre from the corner (see diagram

INSTALLATION

and template)

Note. mark the centre of the hole as well as the
circumference.
If extension duct kit pack D has to be used, the pipes must
have the correct slope as detailed in frame 11.

4 Remove the template from the wall

15 DRILLING THE WALL

Rear flue shown

IMPORTANT

Ensure that, during the cutting operation, masonry falling
outside the building does not cause damage or personal
injury.

1 Cut the flue hole (preferably with a 5” core boring tool),

ensuring that the hole is square to the wall.

2 Drill the fixing holes with an 8mm (5/16”) masonry drill.

Fit suitable wall plugs (not provided).

Note. If the teminal is to be sited within 25 --- 40 mm of a
corner or vertical pipe (refer to Table 4) then the hole MUST
be accurately cut and the rubber weather seal trimmed.

5” diameter
flue hole

Section
through wall

Extended centre

Spirit level

16 FITTING THE WALL

MOUNTING PLATE

Refer to frame 18 for service connections.

Fit the wall mounting plate

Directly to the wall

F Offer up wall mounting plate.
F Screw through the fixing holes using 3 off no. 14x2”

screws (not provided).

F Check alignment with spirit level.
F Tighten screws.

Note: Check all of the hole
positions before drilling.

18

mini HE --- Installation & Servicing