cop_int

GENERAL

Mini --- Installation & Servicing

Table 1 --- Boiler Data

Mini C24

Mini C28

Mini C32

Mini S24

Mini S28

Gas supply type & connection

2H3P

G20 20mbar, G31 37mbar, 22 mm copper

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/in

)

3.0 (43.5)

Max DHW water inlet pressure

bar (lb/in

)

10.0 (145.0)

---

Min DHW water inlet pressure

bar (lb/in

)

0.3 (4.4)

---

Electrical supply

230 Vac 50 Hz

Max power consumption

150

170

180

150

170

External fuse rating

3 A

Internal fuse rating

T 2A

Water content --- CH

litre (gal.)

1.0 (0.22)

1.1 (0.242)

1.0 (0.22)

1.1 (0.242)

Water content --- DHW

litre (gal.)

0.2 (0.044)

---

Dry weight

kg (lb.)

37 (81.6)

39 (86.0)

36 (79.4)

38 (83.8)

Size: Height / Width / Depth

mm (in.)

703 (27 11/16") / 400 (15 3/4") / 310 (12 3/16")

Lift weight

kg (lb.)

35.5 (78.4)

36.5 (80.6)

34.5 (76.2)

35.5 (78.4)

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

Mini C24

Mini S24

Mini C28

Mini S28

Mini C32

Max

Min

Max

Min

Max

Min

Burner pressure (Hot)

G20

G31

mbar

(in.w.g.)

11.7 (4.7)

35.7 (14.3)

1.8 (0.7)

6.1 (2.4)

11.7 (4.7)

35.7 (14.3)

1.2 (0.5)

5.7 (2.3)

10.5 (4.2)

35.7 (14.3)

1.5 (0.6)

6.7 (2.7)

Input based on nett CV

(btu/h)

26.60

(90 759)

11.00

(37 532)

31.10

(106 113)

13.00

(44 356)

35.20

(120 102)

15.50

(52 886)

Input based on gross CV

(btu/h)

29.52

(100 732)

12.21

(41 656)

34.52

(117 773)

14.43

(49 230)

39.07

(133 306)

17.20

(58 686)

Output

(btu/h)

24.30

(82 912)

9.10

(31 049)

28.36

(96 764)

11.00

(37 532)

32,00

(109 184)

12,73

(43 435)

Gas consumption (Hot) G20

G31

l/s (ft

/h)

l/s

0.763 (97.0)

0.309

0.315 (40.1)

0.128

0.892 (113.5)

0.361

0.373 (47.4)

0.151

1.035 (131.7)

0.400

0.456 (58.0)

0.176

Seasonal efficiency*

(SEDBUK)

Band D

78.2

Band D

78.3

Band D

79.4

NOx classification

Class 3

Class 2

Class 3

*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 C24

Mini C28

Mini C32

Maximum

Burner pressure (Hot)

G20

G31

mbar

(in.w.g.)

11.7 (4.7)

35.7 (14.3)

11.7 (4.7)

35.7 (14.3)

10.5 (4.2)

35.7 (14.3)

Input based on nett CV

kW (btu/h)

26.60 (90 759)

31.10 (106 113)

35.20 (120 102)

Input based on gross CV

kW (btu/h)

29.52 (100 732)

34.52 (117 773)

39,07 (133 306)

Output

kW (btu/h)

24.30 (82 912)

28.36 (96 764)

32,00 (109 184)

Gas consumption (Hot) G20

G31

l/s (ft

/h)

l/s

0.763 (97.0)

0.309

0.892 (113.5)

0.361

1.035 (131.7)

0.400

Flow 35 ° C temp. rise

l/m (gpm)

10.0 (2.2)

11.6 (2,6)

13.1 (2.9)

Domestic hot water specific

rate

l/m (gpm)

11.6 (2.6)

13.6 (3,0)

15.3 (3.4)

Note: the 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 different calorific value: ---
a.

FOR L/S --- divide the gross heat input (kW) by the gross

C.V. of the gas (MJ/m

)

FOR FT

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

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

)

Key to Symbols:

IE = Ireland, GB = United Kingdom (Countries of destination)

PMS = Maximum operating pressure of water

= a room sealed appliance designed for

connection via concentric ducts to a horizontal or vertical

terminal or twin flue system.

2H3P

= appliance designed for use on 2nd family gas group

H or 3rd family gas group 3P

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.

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GENERAL

Mini Installation & Servicing

Mini

Mini C24

G.C. appliance No. 47---348---18

Mini C28

G.C. appliance No. 47---348---19

Mini C32

G.C. appliance No. 47---348---25A

Mini S24

G.C. appliance No. 41---392---98

Mini S28

G.C. appliance No. 41---392---99

PI No.

0694BM3420

Destination countries: GB, IE

CONTENTS

Air supply

Boiler clearances

Boiler exploded view

Electrical connections

Electrical supply

Fault finding

Flow wiring diagram

Flue fitting

Gas conversion

Gas safety regulations

Gas supply

Installation

Mandatory requirements

Replacement of components

Servicing

Short list of parts

Thermostatic radiator valves

Water connections

Water treatment

Wiring diagrams

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 log book.

Benchmark Log Book Details

Boiler

Page

Make and model

Appliance serial no. on data badge

SEDBUK No. %

Controls
Time and temperature control to heating

23/24

Time and temperature control to hot water

Heating zone valves

TRV's

Auto bypass

Boiler interlock

For all boilers
Flushing to BS.7593

Inhibitor

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

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

n/a

For all boilers:

complete, sign & hand over to customer

For assistance see Technical Helpline on the back page

NOTE TO THE INSTALLER: leave these

instructions adjacent to the gas meter.

Also complete the benchmark log book and give

this to the customer

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GENERAL

Mini --- Installation & Servicing

BOILER WATER CONNECTION

6
5

(
2

9
/
1
6
"
)

85 (3 5/16")

255 (10")

5
6
1

(
2
2

1
/
1
6
"
)

1
0
1

(
4
"
)

8
3

(
3

1
/
4
"
)

6
5

(
2

9
/
1
6
"
)

5
2

(
2
"
)

6
4

(
2

1
/
2
"
)

Wall

mounting

plate

r
e
t
u
r
n

f
l
o
w

h
o
t
o
u
t
l
e
t
*

c
o
l
d

i
n
l
e
t
*

a
s

i
n
l
e
t

20 (3/4")

Pipe size

O.D. mm

CH flow

CH return

Gas inlet

DHW cold inlet *

DHW hot outlet *

* Pipe connections not used on system boilers

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.

25 (1")

50 (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.
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.

147 (5 3/4")

9
2

(
3

5
/
8
"
)

200 (7 7/8")

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GENERAL

Mini Installation & Servicing

INTRODUCTION

Mini C24, Mini C28 and Mini C32 are wall mounted, low

water content, balanced

flue combination gas boilers.

Mini S24 and Mini S28 are wall mounted, low water content,

balanced

flue system gas boilers.

Central heating (CH) output and domestic hot water (DHW)

output (on combination versions) are both fully modulating:

--- between 9.10 (31 049) and 24.30 (82 912) kW (btu/h) for

model

Mini C24 and Mini S24;

--- between 11.00 (37 532) and 28.00 (95 536) kW (btu/h) for

model

Mini C28 and Mini S28.

--- between 12.73 (43 435) and 32.00 (109 184) kW (btu/h) for

model

Mini C32.

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 vessels are provided.
The CH flow temperature is controlled by an electronic

thermostat. 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 DHW heat exchanger is 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 (

Mini C24, Mini C28, Mini C32 only) fits

neatly within the casing. Separate fitting instructions are

included with the kit. Note. If using an alternative programmer

read Frame 26 first.
Horizontal Concentric Extension Ducts
Up to 4 m (13' 1") for models:

Mini C24, Mini S24, Mini C28, Mini S28.
Up to 2,7 m (8' 10") for model Mini C32
Other available kits are listed in frame 9.

DHW OPERATION (combi versions)

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 C24. 10.0 (2.2) l/min (gpm) at 35 degree rise.
Mini C28 11.6 (2.6) l/min (gpm) at 35 degree rise.
Mini C32 13.1 (2.9) 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

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 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

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.

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GENERAL

Mini --- Installation & Servicing

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)

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

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

Minimum spacing

1 Directly below, above or along side

of an openable window, air vent or

other ventilation opening

300 mm (12")

2 Below guttering, drain pipes or soil

pipes

75 mm ( 3") **

3 Below eaves

200 mm ( 8") **

4 Below balconies or a car port roof

300 mm ( 12") **

5 From vertical drain pipes or soil

pipes*

60 mm ( 2 1/2") **

6 From an internal or external corner

or to a boundary along side the

terminal

150 mm ( 6") **

7 Above adjacent ground, roof or

balcony level

300 mm (12")

8 From a surface or a boundary

facing the terminal.

600 mm (24")

9 From a terminal facing a terminal

1200 mm (48")

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

door or window) into dwelling

1200 mm (48")

11 Vertically from a terminal on the

same wall

1500 mm (60")

12 Horizontally from a terminal on the

wall

300 mm (12")

* 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.
** If a reduction down to 25mm(1") is required in any of the

indicated positions, horizontal flue kit no. 200889

MUST be

used.

Only 1 reduction down to 25mm is allowable per

installation.

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GENERAL

Mini Installation & Servicing

Vertical Terminals

13 Above the roof pitch with roof

slope of all angles.

Above flat roof

300 mm (12")

14 From single wall face

From corner wall faces

600 mm (24")

1000 mm (40")

Twin Flue Applications

15 Centre distance between air inlet

and flue outlet ducts

120mm (5")

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. +44 (0) 1732 359 888 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.

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 2.

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.
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:

Fernox

Cookson Electronics

Forsyth Road

Sheerwater

Woking

Surrey

GU21 5RZ

+44 (0) 1799 550811

Calmag Ltd.

Unit 4 Crown Works

Bradford Road

Sandbeds

Keighley

West Yorkshire

BD20 5LN

+44 (0) 1535 210320

Salamander (Eng) Ltd

Reddicap Trading Estate

Sutton Coldfield

West Midlands

B75 7BY

+44 (0) 121 378 0952

GE Betz

Sentinel Division

Foundry Lane

Widnes

Cheshire

WA8 8UD

+44 (0) 151 420 9563

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GENERAL

Mini --- Installation & Servicing

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.

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.

SEALED SYSTEM REQUIREMENTS

Central Heating

Note. Mini 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/in

) 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/in

. 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/in

For further details refer to BS.5449:1 and the British Gas

Corporation publication 'Specifications for Domestic Central

Heating and Hot Water'.
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

r
e
t
u
r
n

Hose unions

Mains

Water

Supply

Temporary hose

(disconnect

after filling)

Stop valve

Additional stop valve

Double check valve

assembly

Note direction of flow

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.

Fill and vent the system until the pressure gauge registers

1.5 bar (22 lb/in

). Examine for leaks.

Release water from the system until a pressure of 1 bar

(15 lb/in

) is reached.

To avoid getting debris on the valve seat, do not use

the safety valve to do this.

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.

Re---pressurise the system to the desired charge pressure

(see Table 5).

Table 5 Mini C24, Mini S24, Mini C28, Mini S28
System charge pressure

(bar)

0.5

0.7

1.0

Safety valve setting

3.0

Vessel pre---charge pressure

(bar)

0.7

System volume (litres)

Volume of expansion vessel

in addition to 6 litre unit

fitted to boiler

---

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