Ideal Heating Keston COMBI2 C30 User guide

When replacing any part on this appliance, use only spare parts that you can be assured conform to the safety and performance
specification that we require. Do not use reconditioned or copy parts that have not been clearly authorised by Keston.
For the very latest copy of literature for specification and maintenance practices visit our website keston.co.uk
where you can download the relevant information in PDF format.
INSTALLATION
& SERVICING
COMBI2
C30 C35
04 / 2023
UIN 236467 A03

ERP DATA
The code of practice for the installation,
commissioning & servicing of central
heating systems
WEEE DIRECTIVE 2012/19/EU
Waste Electrical and Electronic Equipment Directive
• At the end of the product life, dispose of the
packaging
and product in a corresponding recycle centre.
• Do not dispose of the unit with the usual domestic refuse.
• Do not burn the product.
• Remove the batteries.
• Dispose of the batteries according to the local statutory
requirements and not with the usual domestic refuse.
 
MODEL
SYMBOL UNITS 30 kW 35 kW
Condensing Boiler n/a n/a yes yes
Low Temperature Boiler n/a n/a no no
B1 Boiler n/a n/a no no
Cogeneration Space Heater n/a n/a no no
Equipped with a Supplementary Heater n/a n/a no no
Combination Heater n/a n/a yes yes
Nominal Heat Output for Space Heating
Full Load P4 kW 24.3 24.3
Part Load P1 kW 8 8
Auxiliary Electricity Consumption
Full Load elmax kW 0.028 0.028
Part Load elmin kW 0.009 0.026
Standby PSB kW 0.003 0.002
Seasonal Space Heating Energy E󰀩ciency
Full Load ƞ4 % 90 90
Part Load ƞ1 % 98.6 98.6
Standby Loss Pstby kW 0.05 0.05
Ignition Pign kW 0 0
Emissions NOx (Gross) NOx, pond Hs mg/kWh 25 30
Annual Energy Consumption QHE GJ 75 75
Sound Power Level, Indoors LWA dB 46 46
Domestic Hot Water
Domestic Hot Water Qelec kWh 0.133 0.137
Water heating energy e󰀩ciency (Eco) Tapping Prole L ƞWH % 81 79
Daily fuel consumption 24hr (GCV) Actual measured Qfuel kWh 14.84 15.14
Annual electricity consumption AEC kWh 28 29
Annual fuel consumption AFC GJ 11 11
2
Installation and Servicing

KESTON COMBI²
Ideal Heating ERP DATA
Seasonal Space Heating Energy E󰀩ciency of the Boiler *%
Temperature control (from che of temperature control) %
Class I Class II Class III Class IV Class V Class VI Class VII Class VIII
1% 2% 1.5% 2% 3% 4% 3.5% 5%
PRODUCT FICHE
 
*The energy e󰀩ciency of the package of products provided for in this document may not correspond to its actual energy e󰀩ciency once installed
in a building, as the e󰀩ciency is inuenced by further factors such as heat loss in the products in relation to the building size and its characteristics
Collector Size
(in m2)Tank Volume (in m3)Collector E󰀩ciency
(in %)
Tank rating
A* = 0.95
A = 0.91
B = 0.86
C = 0.83
D-G = 0.81
Solar Contribution (from che of solar device)
Seasonal Space Heating Energy E󰀩ciency of Package TOTAL: A+B+C=
Seasonal Space Heating Energy E󰀩ciency Class of Package
= (‘III ’x + ‘IV ’ x ) x 0.9 x ( / 100 x ) = %
%
GG F E D C B A A+ A++ A+++
< 30% ≥ 30% ≥ 34% ≥ 36% ≥ 75% ≥ 82% ≥ 90% ≥ 98% ≥ 125% ≥ 150%
A
B
C
MODEL
SYMBOL UNITS 30 kW 35 kW
Condensing Boiler n/a n/a yes yes
Low Temperature Boiler n/a n/a no no
B1 Boiler n/a n/a no no
Cogeneration Space Heater n/a n/a no no
Equipped with a Supplementary Heater n/a n/a no no
Combination Heater n/a n/a yes yes
Nominal Heat Output for Space Heating
Full Load P4 kW 24.3 24.3
Part Load P1 kW 8 8
Auxiliary Electricity Consumption
Full Load elmax kW 0.028 0.028
Part Load elmin kW 0.009 0.026
Standby PSB kW 0.003 0.002
Seasonal Space Heating Energy E󰀩ciency
Full Load ƞ4 % 90 90
Part Load ƞ1 % 98.6 98.6
Standby Loss Pstby kW 0.05 0.05
Ignition Pign kW 0 0
Emissions NOx (Gross) NOx, pond Hs mg/kWh 25 30
Annual Energy Consumption QHE GJ 75 75
Sound Power Level, Indoors LWA dB 46 46
Domestic Hot Water
Domestic Hot Water Qelec kWh 0.133 0.137
Water heating energy e󰀩ciency (Eco) Tapping Prole L ƞWH % 81 79
Daily fuel consumption 24hr (GCV) Actual measured Qfuel kWh 14.84 15.14
Annual electricity consumption AEC kWh 28 29
Annual fuel consumption AFC GJ 11 11
SYMBOL UNITS MODEL
30 kW 35 kW
Condensing boiler Yes
Seasonal space heating e󰀩ciency class A
Rated heat output kW 24
Seasonal space heating energy e󰀩ciency ƞs % 94*
Annual energy consumption QHE GJ 75
Sound power level, indoors LWA dB 46 46
Water heating energy e󰀩ciency class A
94%
3Installation and Servicing

Keston reserve the right to vary specication without notice
DEFINITIONS
IMPORTANT: Important information
For any technical queries please ring the Keston installer helpline : 01482 443005
BOILER RESTART PROCEDURE -
Press the RESTART button. The boiler will repeat the ignition sequence if a heat demand is present.
NOTES FOR THE INSTALLER
WARNING: Risk of injury or death
CAUTION: Risk of damage to objects
Table of Acronyms
CH - Central Heating
DHW - Domestic Hot Water
TRV - Thermostatic Radiator Valve
PRV - Pressure Relief Valve
IE - Ireland
ETCI - Electro-Technical Council of Ireland
BS - British Standard
WRAS - Water Regulations Advisory Scheme
SAP - Standard Assessment Procedure
IEE - Institution of Electrical Engineers
UKCA - UK Conformity Assessed
RHS - Right Hand Side
LHS - Left Hand Side
PCB - Printed Circuit Board
4
Installation and Servicing

Section 1 - General.....................................................................................6
1.1 Introduction...................................................................................8
1.2 Operation......................................................................................8
1.3 Safe Handling...............................................................................8
1.4 OptionalAccessories....................................................................8
1.5 Safety............................................................................................8
1.6 Safe Handling of Substances.......................................................9
1.7 Location of Boiler ......................................................................... 9
1.8 Air Supply...................................................................................10
1.9 Gas Supply.................................................................................10
1.10 Water Circulation System........................................................... 10
1.11 Boiler Controls............................................................................10
1.12 Electrical Supply.........................................................................10
1.13 Condensate Drain....................................................................... 10
1.14 Boiler Dimensions, Services & Clearances.................................11
1.15 System Requirements - Central Heating....................................12
1.16 System Requirements - DHW..................................................... 13
1.17 System Balancing.......................................................................13
1.18 Water Treatment......................................................................... 13
Section 2 - Installation..............................................................................14
2.1 BoilerAssembly - Exploded View...............................................14
2.2 Unpacking................................................................................... 15
2.3 Wall Mounting Template.............................................................. 16
2.4 Preparing the Wall...................................................................... 16
2.5 Fitting the Wall Mounting Plate................................................... 16
2.6 Mounting the Boiler..................................................................... 16
2.7 Flue System................................................................................ 17
2.8 Flue System - Continued............................................................18
2.9 Flue Installation Example Keston Combi2C30........................... 19
2.10 Flue Installation Example Keston Combi2 C35............................ 19
2.11 Flue Termination Position........................................................... 20
2.12 Flue Termination Position - Continued........................................ 21
2.13 Assembly Practice......................................................................21
2.14 Fitting the Flue Sleeve................................................................22
2.15 Horizontal Flue Positions............................................................22
2.16 Condensate Drain....................................................................... 23
2.17 Condensate Drain - Cont............................................................24
2.18 Connections & Filling..................................................................25
2.19 Connections & Filling Cont.........................................................26
2.20 Electrical Connections................................................................27
2.21 Installer Wiring............................................................................27
2.22 External Wiring...........................................................................28
2.23 Wiring Diagram...........................................................................29
2.24 Replacing Pre-Fitted Mains Cable..............................................30
2.25 Commissioning and Testing........................................................30
2.26 CH Operation.............................................................................. 31
2.27 The Weather Compensation Kit - Supplied as standard............. 32
2.28 Initial Lighting.............................................................................. 33
2.29 User Interface Commissioning....................................................34
2.30 Changing Boiler Operating Mode ..............................................34
2.31 Preheat Function .......................................................................34
2.32 Intelligent Preheat Function ....................................................... 34
2.33 Menu Operation..........................................................................35
2.34 Setting Maximum and Minimum Rates ...................................... 35
2.35 General Checks..........................................................................36
2.36 Restart Procedure.......................................................................37
2.37 Handing Over.............................................................................. 37
Section 3 - Servicing.................................................................................38
3.1 Servicing Schedule.....................................................................38
3.2 Removal / Replacement of Components....................................39
3.3 Draining the Boiler......................................................................39
3.4 Boiler Front Panel Removal / Replacement................................ 40
3.5 Flue Manifold Removal / Replacement....................................... 40
3.6 Fan and VenturiAssembly Removal and Cleaning..................... 41
3.7 Burner Removal and Cleaning....................................................42
3.8 Cleaning the Heat Exchanger..................................................... 42
3.9 Ignition / Detection Electrode Replacement / Inspection............43
3.10 Cleaning the Condensate Trap................................................... 43
3.11 DHW Filter & DHW Flow Regulator Cleaning / Replacement..... 44
3.12 Burner Injector Replacement......................................................44
3.13 Burner Replacement................................................................... 44
3.14 Return Thermistor Replacement.................................................45
3.15 Spark Generator Replacement...................................................45
3.16 Gas Control Valve Replacement.................................................46
3.17 Diverter Valve Actuator Replacement.........................................46
3.18 Condensate Trap Replacement / Cleaning................................. 46
3.19 Primary PCB Replacement......................................................... 47
3.20 DHW Flow Turbine Sensor Replacement................................... 48
3.21 Pressure Gauge Replacement...................................................48
3.22 PRV Replacement......................................................................49
3.23 PumpAutomaticAir Vent Replacement...................................... 49
3.24 Replacement of DHW Thermistor............................................... 50
3.25 DHW Plate Heat Exchanger Replacement.................................50
3.26 Diverter Valve Body Assembly Replacement..............................51
3.27 CH Water Pressure Switch Replacement................................... 52
3.28 Pump Head Replacement...........................................................52
3.29 Flow Thermistor Replacement....................................................53
3.30 Heat Engine Replacement.......................................................... 54
3.31 Expansion Vessel Recharging & Replacement.......................... 55
Section 4 - Fault Finding...........................................................................56
4.1 Main Menu, Fault Help................................................................56
4.2 Overheat Lockout.......................................................................56
4.3 Ignition Lockout........................................................................... 57
4.4 Flame On Before Gas Valve On.................................................57
4.5 Low Water Pressure................................................................... 57
4.6 Flame Loss.................................................................................58
4.7 Fan Fault..................................................................................... 58
4.8 Flow Thermistor Fault ................................................................59
4.9 Return Thermistor Fault ............................................................. 59
4.10 Outside Sensor Fault..................................................................60
4.11 No CH Operation but DHW works OK........................................60
4.12 No DHW but CH Works OK........................................................61
4.13 No Display..................................................................................62
4.14 DHW Thermistor Fault................................................................62
Section 5 - Spare Parts............................................................................63
Section 6 - Benchmark to Commissioning................................................ 64
CONTENTS
5Installation and Servicing

Table 1 General Data
Note. Gas consumption is calculated using a caloric value of
38.7 MJ/m
3
(1038 Btu/ft
3
) gross or 34.9 MJ/m
3
(935 Btu/ft
3
) nett.
To obtain the gas consumption at a di󰀨erent caloric value:
a. For l/s - divide the gross heat input (kW) by the gross C.V. of
the gas (MJ/m3)
b. For Btu/h - multiply the gross heat input (kW) by 26.8
c. For ft3/h - divide the gross heat input (Btu/h) by the gross C.V.
of the gas (Btu/ft3)
d. For m3/h - multiply l/s by 3.6
C13 C33 C53 = 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 orices which, in
this case, are concentric. The fan is up stream of the
combustion chamber.
I2H = An appliance designed for use on 2nd family gas, Group H
only .
II2H/3P = An appliance designed for use on 2nd or 3rd family gases,
Group H or P .
* The value is used in the UK Government’s Standard Assessment
Procedure(SAP)forenergyratingof dwellings. The test data from which
it has been calculated, has been certied by a notied body.
** Thevalueisusedinthe Irish Government’s DwellingEnergyAssessment
Procedure (DEAP) for energy rating of dwellings. The test data from
which it has been calculated have been certied by a notied body.
*Required for maximum ow rate. Boiler operates down to 2 L/min DHW delivery ** In areas of low water pressure the DHW restrictor can be removed
30 kW 35 kW
Gas Supply 2H - G20 - 20 mbar
Gas Supply Connection 15 mm copper compression
Injector Size mm 4.65 4.9
Inlet Connection Cold Water 15 mm copper compression
Outlet Connection Cold Hot Water 15 mm copper compression
Flow Connection Central Heating 22 mm copper compression
Return Connection Central Heating 22 mm copper compression
Flue Terminal Diameter mm 50
Average Flue Temp-Mass Flow Rate DHW 68ºC - 13g/s 73ºC - 15g/s
CO2 Content (± 0.7) Max. DHW 9.3% 9.7%
Min. CH 8.5% 8.8%
Maximum Working Pressure (Sealed Systems) bar (psi) 2.5 (36.3)
Maximum Domestic Hot Water Inlet Pressure bar (psi) [kPa] 10.0(145)[1000]
Minimum Domestic Hot Water Inlet Pressure* bar (psi) [kPa] 1.3(18.9) [130] 1.3(18.9)**[130]
Minimum DHW Inlet Pressure to Operate at 0.6 bar System
Pressure All Model Sizes 0.5 bar
Electrical Supply 230 V ~ 50 Hz
Power Consumption W 93 110
Fuse Rating External : 3 A Internal : T4A HRC L250 V
Water Content Central Heating litre (gal) 1.2 (0.26)
Domestic Hot Water litre (gal) 1.0 (0.22)
Packaged Weight kg 32.9 32.9
Lift Weight kg 28.6 28.6
Boiler Casing Size Height mm 700
Width mm 395
Depth mm 278
Boiler Input: Max Min
30 kW 35 kW
kW 24.3 6.1 7.1
Gross CV kW 27 6.7 7.9
Gas Consumption m3/h 2.512 0.627 0.734
(ft3/h) (89) (22) (25.9)
Boiler Output :
Non Condensing
70ºC Mean Water Temp. kW 24.2 6.1 7.1
Condensing
40ºC Mean Water Temp. kW 25.6 6.4 7.5
Seasonal E󰀩ciency* SEDBUK 2005 91.10% 91.10%
Seasonal E󰀩ciency* SEDBUK 2009/2012 89.60% 89.60%
SEAI HARP* 91.10% 91.10%
NOx Classication CLASS 6
Maximum DHW Input: 30 kW 35 kW
Nett CV kW 30.4 35.4
Gross CV kW 33.7 39.3
Gas Consumption m3/h 3.135 3.657
ft3/h 111 129
Maximum DHW Output kW 30.3 35.3
DHW Flow Rate l/min 12.4 14.5
At 35ºC Temp. Rise gpm 2.8 3.2
DHW Specic Rate l/min 14.5 16.9
gpm 3.2 3.7
6
Installation and Servicing
Section 1 - General
Table 2 Performance Data - Central Heating Table 3 Performance Data - Domestic Hot Water

Boiler Page
Make and model.........................................................7
Appliance serial no. on data badge ..........Front Cover
SEDBUK No. %..........................................................6
Controls
Time and temperature control to heating .................28
Time and temperature control to hot water ............n/a
Heating zone valves.................................................13
TRVs........................................................................13
Auto bypass .............................................................13
Boiler interlock..........................................................13
For all boilers
Flushing to BS.7593.................................................13
Inhibitor ....................................................................13
Central heating mode
Heat input...................................................to be calculated
For assistance call
Technical Helpline
01482 443005
Page
Burner operating pressure ......................................n/a
Central heating ow temp. ...........measure and record
Central heating return temp. ........measure and record
For combination boilers only
Scale reducer...........................................................13
Hot water mode
Heat input............................................to be calculated
Max. operating burner pressure..............................n/a
Max. operating water pressure........ measure & record
Cold water inlet temp ...................... measure & record
Hot water outlet temp...................... measure & record
Water ow rate at max. setting........ measure & record
For condensing boilers only
Condensate drain................................................23-24
For all boilers: Complete, sign & hand over to customer
For UK intallations, to comply with Building Regulations Part L1 (Part 6 in Scotland), the boiler should be tted in accordance with
the manufacturer’s instructions. Self-certication that the boiler has been installed to comply with Building Regulations can be
demonstrated by completing and signing the Benchmark Commissioning Checklist.
Before installing this boiler, read the Code of Practice sheet at the rear of this book.
BENCHMARK COMMISSIONING CHECKLIST DETAILS
NOTE TOTHE INSTALLER: COMPLETETHE BENCHMARK COMMISSIONING CHECKLIST
AND LEAVE THESE INSTRUCTIONS WITHAPPLIANCE
Natural Gas Only
Destination Country: GB, IE, RO
KESTON COMBI2C
BOILER SIZE kW G.C. Applicance No
(Benchmark No.)
30 47-930-09
35 47-930-10
30 kW 35 kW
Gas Supply 2H - G20 - 20 mbar
Gas Supply Connection 15 mm copper compression
Injector Size mm 4.65 4.9
Inlet Connection Cold Water 15 mm copper compression
Outlet Connection Cold Hot Water 15 mm copper compression
Flow Connection Central Heating 22 mm copper compression
Return Connection Central Heating 22 mm copper compression
Flue Terminal Diameter mm 50
Average Flue Temp-Mass Flow Rate DHW 68ºC - 13g/s 73ºC - 15g/s
CO2 Content (± 0.7) Max. DHW 9.3% 9.7%
Min. CH 8.5% 8.8%
Maximum Working Pressure (Sealed Systems) bar (psi) 2.5 (36.3)
Maximum Domestic Hot Water Inlet Pressure bar (psi) [kPa] 10.0(145)[1000]
Minimum Domestic Hot Water Inlet Pressure* bar (psi) [kPa] 1.3(18.9) [130] 1.3(18.9)**[130]
Minimum DHW Inlet Pressure to Operate at 0.6 bar System
Pressure All Model Sizes 0.5 bar
Electrical Supply 230 V ~ 50 Hz
Power Consumption W 93 110
Fuse Rating External : 3 A Internal : T4A HRC L250 V
Water Content Central Heating litre (gal) 1.2 (0.26)
Domestic Hot Water litre (gal) 1.0 (0.22)
Packaged Weight kg 32.9 32.9
Lift Weight kg 28.6 28.6
Boiler Casing Size Height mm 700
Width mm 395
Depth mm 278
7Installation and Servicing
Section 1 - General

1.1 INTRODUCTION
The Keston Combi2range of boilers are wall mounted,
condensing, combination gas boilers.
Features:
• High e󰀩ciency
• Full sequence
• Automatic spark ignition
• Low water content
• Fanned ue
The boiler is supplied fully assembled with a DHW plate heat
exchanger, diverter valve, circulating pump, pressure gauge,
PRV and CH expansion vessel.
Variable CH and DHW temperature controls are tted on the
user control and the boiler features a DHW preheat facility.
The boiler includes as standard:
- Automatic boiler bypass
- Boiler frost protection
- Daily pump and diverter valve exercise
The boiler casing is of white painted mild steel with a white
polymer front panel.
The boiler temperature controls are visibly located in the
control panel on the front of the boiler.
The heat exchanger is manufactured from cast aluminium.
The boiler is suitable for connection to fully pumped,
sealed heating systems ONLY. Adequate arrangements for
completely draining the system by provision of drain cocks
MUST be provided in the installation pipework.
Pipework from the boiler is routed downwards.
Data Plate
The boiler model and serial number are shown on the data
label which can be located on the bottom of the boiler casing,
shown in - Water & Gas Connection Diagram.
Refer to Section
1.14
1.2 OPERATION
With no demand for CH, the boiler res only when DHW is
drawn o󰀨, or periodically for a few seconds without any DHW
draw-o󰀨, in order to maintain the DHW plate heat exchanger
in a heated condition. This only occurs if the “PREHEAT”
button is pressed and the display reads “PREHEAT ON or
PREHEAT TIMED”.
When there is a demand for CH, the heating system is
supplied at the selected temperature of between 30oC and
80oC, until DHW is drawn o󰀨. The full output from the boiler is
then directed via the diverter valve to the plate heat exchanger
to supply a nominal DHW draw-o󰀨 of:
30 kW 12.4 l/min at 35ºC temperature rise.
35 kW 14.5 l/min at 35ºC temperature rise.
The DHW draw o󰀨 rate specied above is the nominal that the
boiler ow regulator will give. Due to system variations and
seasonal temperature uctuations DHW ow rates/temperature
rise will vary, requiring adjustment at the draw o󰀨 tap.
At low DHW draw-o󰀨 rates the maximum temperature may
exceed 65ºC.
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 nding.
1.3 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 personal protective equipment 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.
1.4 OPTIONALACCESSORIES
Please visit keston.co.uk to access the optional accessories for
this boiler.
1.5 SAFETY
Current Gas Safety (installation and use) regulations or
rules in force:
The appliance is suitable only for installation in the UK and
should be installed in accordance with the rules in force.
In the UK, installations must be carried out by a Gas Safe
Registered Engineer. It must be carried out in accordance with
the relevant requirements of the:
• Gas Safety (Installation and Use) Regulations.
• Appropriate Building Regulations, either The Building
Regulations, The Building Regulations (Scotland), Building
Regulations (Northern Ireland).
• Water Fittings Regulations or Water byelaws in Scotland.
• Current I.E.E. Wiring Regulations.
Where no specic instructions are given, reference should be
made to the relevant British Standard Code of Practice.
8
Installation and Servicing
Section 1 - General

In IE , the Installation must be carried out by a Registered Gas
Installer (RGII) and installed in accordance with the current
edition of I.S.813 “Domestic Gas Installation”, the current
Building Regulations and reference made to the current ETCI
rules for electrical installation.
The Boiler has been tested and certied to:
BSEN 15502-1, BSEN 15502-2, BSEN 15502-2-1,
BSEN 60335-1, BSEN 60335-2-102, BSEN 55014-1 and
BSEN 55014-2 for use with Natural Gas & Propane.
Detailed recommendations are contained in the following
British Standard Codes of Practice:
BS5440:1 Flues (for gas appliances of rated input not
exceeding 70 kW).
BS5440:2 Ventilation (for gas appliances of rated input
not exceeding 70 kW).
BSEN12828 Heating Systems in buildings: Design for water
based heating systems.
BSEN12831 Heating Systems in buildings: Method for
calculation of the design heat load.
BSEN14336 Heating Systems in buildings: Installation
and commissioning of water based heating
systems.
BS5546 Installation of gas hot water supplies for
domestic purposes (2nd Family Gases)
BS6798 Installation of gas red hot water boilers of
rated input not exceeding 70 kW.
BS6891 Installation and maintenance of low pressure
gas installation pipework.
BS 7593:2019 Code of practice for the preparation,
commissioning and maintenance of domestic
central heating and cooling water systems.
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: This appliance is UKCA/CE certicated for
safety and performance. Do not connect external control devices
directly to this appliance unless recommended in this manual or
by Keston in writing. If in doubt, please enquire.
Unapproved control devices could invalidate the warranty of this
appliance and infringe the Gas Safety Regulations.
1.6 SAFE HANDLING OF SUBSTANCES
No asbestos, mercury or CFCs are included in any part of the
boiler or its manufacture.
1.7 LOCATION OF BOILER
The boiler must be installed on a at and vertical internal wall,
capable of adequately supporting the weight of the boiler and
any ancillary equipment.
The boiler may be tted on a combustible wall and insulation
between the wall and the boiler is not necessary, unless
required by the local authority.
WARNING: Rear access to the boiler is not permitted.
CAUTION: Do not t the boiler outside.
Timber Framed Buildings
Boilers installed in a timber-framed building must comply with
IGE/UP7 +A 2008.
High Rise Installations
Installations in England above 18 meters requires a High
Rise Flue Kit. This adheres to the new building regulations.
(ADB_Vol1_ Dwellings_2019_edition_inc_2020_
amendments).
Installations in Scotland above 11 meters requires the High
Rise Flue Kit. This adheres to the new building standards
technical handbook 2020: Domestic Buildings (April 2021
Addendum).
Bathroom Installations
You may install the boiler in any internal space. The
installation must comply with the current IEE (BS 7671)
Wiring Regulations and the electrical regulations applicable in
Scotland.
For IE, reference should be made to the current ETCI rules for
electrical installations and I.S.813
If the appliance is to be installed in a room containing a bath
or shower then the appliance must be installed beyond Zone
2, as detailed in BS7671.
Bathroom Installations
[0] Zone 0
[1] Zone 1
[2] Zone 2
[2*] Without the end wall, zone 2 must extend 600 mm from the bath
[A] 600 mm radius from the bath or shower
0010017086-002
2
12
12
2
1
600 mm
600 mm
600 mm
2250 mm
2250 mm
2*
A
A
A
600
m
m
CAUTION: This appliance is IP20 rated, do not clean
with jets of water.
9Installation and Servicing
Section 1 - General

The complete installation MUST be tested for gas tightness
and purged as described, for the majority of installations the
appropriate standard is IGEM/UP/1B [23], but alternatively
IGEM/UP/1 [21] or IGEM/UP/1A [22], as appropriate, can be
utilized.
1.10 WATER CIRCULATION SYSTEM
IMPORTANT: A minimum length of 1 metre of copper
pipe MUST be tted to both ow and return connections from
the boiler before connection to any plastic piping.
The central heating system should be in accordance with
BS6798 and, in addition, for smallbore and microbore systems,
BS EN 12828:2012+A1:2014.
Water treatment is covered later in these instructions.
Refer to Section
1.18
1.11 BOILER CONTROLS
Install CH controls to ensure that the boiler has no demand
when there is no requirement from the system.
Heating systems with TRVs in individual rooms must include a
thermostat to control the temperature in rooms without TRVs.
At least 10% of the minimum boiler heat output should be
achieved using a room thermostat. A bypass circuit with an
automatic bypass valve must be tted to systems with TRVs or
two-port valves on all the radiators to ensure water ow.
1.12 ELECTRICALSUPPLY
WARNING: This appliance must be earthed.
Wiring external to the appliance MUST be in accordance with
the current I.E.E. (BS7671) Wiring Regulations and any local
regulations which apply.
For IE, reference should be made to the current ETCI rules for
electrical installations.
The mains supply to the boiler and system wiring centre
shall be through one common fused double pole isolator and
for new heating systems, and where practical replacement
installations, the isolator shall be situated adjacent to the
appliance.
1.13 CONDENSATE DRAIN
The condensate drain provided must be connected to the
drainage point on site. All condensate drainage pipework and
ttings must be made of plastic.
IMPORTANT: The condensate drain pipework should
be installed in accordance with BS6798.
The drain outlet on the boiler is sized for standard 21.5 mm
overow pipe. It is a universal tting to allow use of di󰀨erent
brands of pipework.
Refer to Section
2.16
Compartment Installations
A boiler installed in a compartment does not require ventilation.
However, a boiler installed in a compartment must provide
adequate clearances for servicing. The compartment should
also be tted with a suitable label in accordance with current
standards.
Refer to Section
1.14
1.8 AIR SUPPLY
It is not necessary to have an air vent in the room or internal
space where the boiler is installed.
1.9 GAS SUPPLY
Consult the local gas supplier to establish an adequate supply
of gas. Do not use existing service pipes without consulting the
local gas supplier.
The gas supply must be governed with a meter.
A gas meter can only be connected by the local gas supplier or
by a Gas Safe Registered Engineer or in IE a Registered Gas
Installer.
An existing meter should be checked, preferably by the gas
supplier, to ensure that the meter is adequate to deal with the
required gas supply rate.
It is the responsibility of the Gas Installer to size the gas
installation pipework in accordance with BS6891.
Whilst the principle of the 1:1 gas valve ensures the Keston
range is able to deliver it is full output at inlet pressures as low
as 14 mb, other gas appliances in the property may not be as
tolerant. When operating pressures are found to be below the
minimum meter outlet of 19 mb these should be checked to
ensure this is adequate for correct and safe operation.
Allowing for the acceptable pressure loss of 1mb across the
installation pipework, it can be assumed that a minimum
permitted operating pressure of 18mb will be delivered to the
inlet of the appliance.
(Reference BS6400-1 Clause 6.2 Pressure Absorption).
The external gas cock could further reduce the operating
pressure when measured at its test point. The pressure drop
is relative to the heat input to the boiler (kW), refer to graph
below.
Gas Cock Pressure Drop
Heat Input to Boiler (kW)
Pressure Drop (mbar)
0 5 10 15 20 25 30 35 40
1.4
1.2
1
0.8
0.6
0.4
0.2
0
IMPORTANT: Ensure all gas valve connections are gas
tight with a gas soundness check up to the gas control valve.
Installation pipes must be tted in accordance with BS6891.
10
Installation and Servicing
Section 1 - General

1.14 BOILER DIMENSIONS, SERVICES & CLEARANCES
The boiler connections are made on the boiler connection
tails.
Front Clearance
The minimum front clearance when built in to a cupboard is
5 mm from the cupboard door but 450 mm overall clearance
is still required, with the cupboard door open, to allow for
servicing.
* Bottom Clearance
Bottom clearance after installation can be reduced to 15
mm.
This must be obtained with an easily removable panel to
provide the 100 mm clearance required for servicing.
For easy access to the pressure gauge a bottom
clearance of 15 mm is required for a partial open door.
395
75
61
36
21
33
32
43.5 94
Refer to Section
2.18
278
700
100*
Flue
terminal
2.52.5
from case
Underside View
Water and Gas Connections
CH
Flow DHW Outlet Gas DHW Inlet CH Return CH Circuit Drain
Data
Plate
CH
Flow DHW Outlet
PRV
CH
Return
DHW
Inlet
Gas
Inlet
Cond.
Drain
PRV
Cond.
Drain
89
155
IMPORTANT: Please ensure there is su󰀩cient
clearance either side and below the boiler, particularly from
door hinges and the base of a cupboard, to allow the door to
be opened to allow the pressure gauge to be checked.
56.5
65 37.5
56.5
65 37.5
56.5
65 37.5
The following minimum clearances must be maintained
for operation and servicing.
Additional space will be required for installation, depending
upon site conditions.
Air Flue
400
62 198
All measurements shown in mm
11Installation and Servicing
Section 1 - General

a. The method of lling, relling, topping up or
ushing sealed primary hot water circuits from the
mains via a temporary hose connection is only
allowed if acceptable to the local water authority.
b. Antifreeze uid, corrosion and scale inhibitor uids
suitable for use with boilers having aluminium
heat exchangers may be used in the central
heating system.
General
1. The installation must comply with national and local
regulations.
2. Design the system for ow temperatures up to 80oC.
3. The system components must be suitable for an
operatingpressure of3bar anda maximumtemperature
of 110°C.
The following components are incorporated within the
appliance:
a. Circulating pump.
b. PRV, with a non-adjustable preset lift pressure of 3
bar.
c. Pressure gauge, covering a range of 0 to 4 bar.
d. An 8 litre expansion vessel, with an initial charge
pressure of 0.75 bar.
4. Makeup Water
One of the following provisions must be made for
replacing system water loss:
a. Manually lled vessel
The vessel must:
•Have a visible water level
•Bemounted atleast 150mm abovethe system’s
highest point
•Connect through a non-return valve to the
system
•Beat least150 mm belowthe makeupvessel on
the return side of the radiators
b. System prepressurisation.
The e󰀩ciency of the expansion vessel will be
reduced in a pressurised system; a larger vessel
or smaller system volume may be necessary. If
the vessel’s capacity is not su󰀩cient, an additional
vessel must be installed on the return to the
boiler.
If the system is not pressurised, the cold water
capacity must not exceed 143 litres.
Guidance on vessel sizing is given in Table 4.
1.15 SYSTEM REQUIREMENTS - CENTRALHEATING
PRV setting bar 3.0
Vessel charge pressure bar 0.5 to 0.75
System pre-charge pressure bar None 1.0
System volume Expansion vessel
(litres) volume (litres)
25 1.6 1.8
50 3.1 3.7
75 4.7 5.5
100 6.3 7.4
125 7.8 9.2
150 9.4 11.0
175 10.9 12.9
190 11.9 14.0
200 12.5 14.7
250 15.6 18.4
300 18.8 22.1
For other system volumes
multiply by the factor across 0.063 0.074
5. Filling
The system may be lled by the following method:
Where the mains pressure is excessive, a pressure
reducing valve must be used to facilitate lling.
a. Thoroughly ush out the whole system with cold
water.
b. Fill and vent the system until the pressure gauge
registers 1 bar and examine for leaks.
Refer to Section
2.18
c. Check the operation of the PRV by raising the water
pressure until the valve lifts. This should occur within
0.3 bar of the preset lift pressure.
d. Check no escape of water occurs except at the
discharge point
e. Release water from the system until the
minimum system design pressure is reached;
1.0 bar if the system is to be pre-pressurised.
Water Flow Rate and Pressure Loss
Max CH Output kW 24.2
Water Flow Rate l/min 17.3
(gal/min) (3.8)
Temperature Di󰀨erential oC 20
Head available for System m.w.g. 3.4
(ft.w.g.) (11.1)
12
Installation and Servicing
Section 1 - General
Table 4 Vessel Sizing

The boiler does not normally need a bypass but at least some
radiators on the heating circuit, of load of at least 10% of the
minimum boiler output, must be provided with twin lockshield
valves so that this minimum heating load is always available.
Note. Systems incorporating zone valves which could completely
cut o󰀨 the ow through the system must also include a bypass.
Balancing
1. Set the programmer to ON.
1.18 WATER TREATMENT
1.17 SYSTEM BALANCING
Central Heating
The Keston Combi2range of boilers have an ALUMINIUM
alloy heat exchanger.
IMPORTANT The application of any other treatment
to this product may render the guarantee of Keston invalid.
The Keston System Filter will aid against the build up of iron
oxide debris, however the below water treatment is also
recommended by Keston.
Keston recommend Water Treatment in accordance with the
Benchmark Guidance Notes on Water Treatment in Central
Heating Systems.
If water treatment is used, Keston Heating recommend
only the use of SCALEMASTER SM-1 PRO, FERNOX MBI,
ADEY MC1, SENTINEL X100 or CALMAG CM100 inhibitors and
associated water treatment products, which must be used in
accordance with the manufacturers’ instructions.
1.16 SYSTEM REQUIREMENTS - DHW
Domestic Hot Water
1. The DHW service must be in accordance with BS.5546 &
BS6700.
2. Refer to Table 1 for minimum and maximum working
pressures. In areas of low mains water pressures the
domestic hot water regulator may be removed from the
DHW ow turbine cartridge. The boiler will require the ow
rate to be set to obtain a temperature rise of 35
o
C at the
tap furthest from the boiler.
Refer to Section
3.20
3. The boilers are suitable for connection to most types of
washing machine and dishwasher appliances.
4. If the shower/mixer valve does not incorporate non-return
valves the following must be followed:
a. The cold inlet to the boiler is tted with an approved
anti-vacuum or syphon non-return valve.
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. BS7593:2019 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 articially softened
water is NOT permitted.
4. Under no circumstances should the boiler be red before
the system has been thoroughly ushed.
For further information contact:
Fernox www.fernox.com Tel: [phone]
Sentinel Performance Solutions
www.sentinelprotects.com Tel: [phone]
Scalemaster Water Treatment Products
www.scalemaster.co.uk Tel: [phone]
Calmag Ltd.
www.calmag Ltd.com Tel: [phone]
Adey www.adey.com Tel: [phone]
b. Hot and cold water supplies to the shower are of
equal pressure.
5. Hard Water Areas
Where the water hardness exceeds 200 mg/litre (200 ppm),
it is recommended that a proprietary scale reducing device
is tted into the boiler cold supply within the requirements of
the local water company.
IMPORTANT Provision must be made to
accommodate the expansion of DHW contained within the
appliance. If the DHW inlet contains a back ow prevention
device or non-return valve, e.g. a water meter, then a mini
expansion vessel should be tted between the device and
the boiler in the cold inlet pipe.
Cold water, rising main and pipework in exposed areas
need to be suitably lagged to prevent freezing.
Note DHW Expansion Vessel kit available from Keston.
2. Close the manual or thermostatic valves on all radiators,
leaving the twin lockshield valves (on the radiators
referred to above) in the OPEN position.
3. Turn up the room thermostat and adjust the lockshield
valve to give an uninterrupted ow through the radiator.
These valves should now be left as set.
4. Open all manual or thermostatic radiator valves and
adjust the lockshield valves on the remaining radiators,
to give around 20oC temperature drop at each radiator.
5. Adjust the room thermostat and programmer to
NORMAL settings.
CAUTION: Do not ll the heating system with softened
water. Softened water could enhance corrosion.
Refer to Section
1.11
13Installation and Servicing
Section 1 - General

2.1 BOILERASSEMBLY- EXPLODED VIEW
Note. that item numbers are linked to the spares list
104 CH Return Valve
105 CH Flow Valve
106 DHW Inlet & Outlet
107 Filling Loop Pipe
108 Pump Head
110 Auto Air Vent
111 Diverter Valve Motor
112 Diverter Valve Body & Paddle
113 Pressure Relief Valve
114 Pipe - PRV Outlet
115 Pipe - Flow
116 Pipe - Return
117 Pipe - Expansion Vessel
118 Expansion Vessel
119 Return Group Manifold
120 Flow Group Manifold
121 Plate Heat Exchanger
124 Flow Regulator
127 Flow Sensor/Turbine
131 Water Pressure Switch
135 Pressure Gauge
203 Gas Cock
205 Gas Valve
206 Pipe - Gas Injector
211 Injector Assy
214 Venturi
215 Fan
217 Burner
218 Gasket - Burner
219 Sump Clean Out Cover
223 Flue Manifold
224 Flue Manifold Top
227 Clamp Retaining Flue Turret
228 Hose Condensate Internal
229 Condensate Trap
231 Condensate Outlet Connection
239 Condensate Drain Tube
302 PCB
306 Ignition/Detection Electrode
308 Ignitor Unit
309 Thermistor
313 Ignition Lead
324 Control Box Lid
325 Control Box Front
326 Blank Insert
401 Heat Engine
503 Wall Mounting Bracket
504 Front Panel
505 Fascia
506 Bracket - Spark Generator
507 Bracket - Expansion Vessel
504
505
215
227
224
503
223
214
217
118
507
313
229
326 325 302
324
135
108
117
119
114
121 111
112
219
110
113
218
401
506
306
308
211
205
124
131
116
107
105 106
106 203
104
115
309
228
206
231
127
120
239
309
14
Installation and Servicing
Section 2 - Installation
INSTALLATION

2.2 UNPACKING
The boiler is supplied fully assembled in Pack A.
Pack A Contents
1. Boiler
2. Hardware Pack Box
3. Wall Mounting Plate
4. These Installation/Users Instructions
5. Boiler Warranty
6. Wall Mounting Template
7. PRV Pipe
Hardware Pack
Box Contents
7. 1x HP Box Dividers - 289 x 111 x 57.5 mm
8. 1x Plug Male and Clip
9. 1x Pipe DHW Outlet
10. 1x Pipe Filling Loop
11. 1x Valve DHW Inlet
12. 2x Pipe CH Flow/Return
13. 1x Valve Filling Loop
14. 1x Valve CH G3/4x 22 mm Filling Loop
15. 1x Cap Female
16. 1x Valve CH G3/4x 22 mm
17. 1x Pipe DHW Inlet
18. 1x Nut G1/2 x 16 Brass (Flat)
19. 1x Gas Cock
20. 1x Coupling
Accessory Bag Contents
21. 9x Washers*
22. 2x Wall Plugs
23. 2x Screws
24. 1x Flue Clamp Screw
21
1
2
3
45
6
Unpack and check the contents
*Refer to Valve Washer Template inside box lid.
8
11
19
18
16
12
13
14
17
15
10
9
7
22 23
24
7
B
A
GHJ
F
E
D
C
FLUE PACK CONTENTS
A Flue Adaptor
B Air Spigot
C Terminals - 2 o󰀨
D Flue Sleeve
E Wall Plate
F Wall Seal
G Outside Sensor
H Screws - 4 o󰀨
J Wall Plugs - 4 o󰀨
20
15Installation and Servicing
Section 2 - Installation
INSTALLATION

The wall mounting template is located on the internal
protective packaging.
Note. The template shows the positions of the xing holes
and the position of the air and ue connections. Care MUST
be taken to ensure the correct holes are drilled.
1. Tape template into the selected position. Ensure
squareness by hanging a plumbline as shown.
2. Mark onto the wall the following:
a The wall mounting plate screw positions (choose one
from each group).
b The position of the air and ue when exiting straight out
of the wall where the boiler is mounted.
Note. Mark the centre of the hole as well as the
circumference.
3. Remove the template from the wall.
2.3 WALL MOUNTING TEMPLATE
2.4 PREPARING THE WALL
WARNING Ensure that, during the cutting operation,
masonry falling outside of the building does not cause
damage or personal injury.
1. Cut the ue and air holes (preferably with 60mm core bore
tool) ensuring the holes are square to the wall.
2. Drill 2 holes with a 7.5mm / 8mm masonry drill and insert
the plastic plugs, provided, for the wall mounting plate.
3. Locate 2 No.14 x 50mm screws in the wall mounting plate
(one at each side, in any of the 3 holes provided at each
side) and screw home.
2.5 FITTING THE WALLMOUNTING PLATE
1. Lift the boiler onto the wall mounting plate and locate it
over the 2 tabs.
2.6 MOUNTING THE BOILER
1. Screw the wall mounting plate to the wall using 2 wall
plugs tted previously with the 2 screws provided.
2. Choose one of the 2 sets of slots in left and right bank.
Ensure that at least one of the screws is tted into a top
slot and the mounting bracket is level.
esp9496
Example of fixing
3G10030
X
Section
through wall
Note. Check all of the hole
positions before drilling.
Rear flue only
60mm diameter
holes
IMPORTANT:
Ensure the wall
where the boiler
will be is at.
16
Installation and Servicing
Section 2 - Installation
INSTALLATION

2.7 FLUE SYSTEM
IMPORTANT
When installing a replacement boiler a new ue system is
recommended. However re-using the existing boiler ue
installation is acceptable if the installer checks and conrms:
• The ue pipe is the approved Marley/Polypipe/Terrain/
Wavin 50mm muPVC solvent weld ue system
• The ue installation is upgraded to the most recent ue
standards taking particular care to comply with ues in
voids
• A risk assessment is conducted to conrm the
e󰀨ectiveness of the ue
• The existing ue will last the lifetime of the new appliance
DESIGN
Individual air supply and ue outlet pipes are used as
standard.
The material approved for this application which MUST
be used are:
- Marley muPVC Solvent Weld System (50mm)
- Polypipe System 2000 muPVC solvent weld (50mm)
- Polypipe Terrain 200 muPVC Solvent Weld System
(50mm)
- Wavin OSMA PVC-C Solvent Weld System (50mm)
to BS5255 and/or BSEN1566-11 and BSEN1329, are the
only systems approved for this application.
Polypipe System 2000 muPVC Solvent Weld System (50mm)
Polypipe Code
MU 301 4m length muPVC wastepipe 5/225
MU 313 50mm x 45 deg muPVC obtuse bend
MU 314
50mm x 92.5 deg muPVC swept bend
MU 310 50mm muPVC straight coupling
MU 316 50mm x 92.5 deg muPVC swept tee
Marley muPVC Solvent Weld System (50mm)
Marley Code
KP 304 50mm x 4m double spigot pipe
KP32 50mm x 45 deg bend
KSC3 50mm straight coupling
KB3 50mm x 88.5 deg bend
KT3 50mm swept tee
Polypipe Terrain Solvent Weld System (50mm)
Polypipe Code
200.2.40 4m length muPVC wastepipe
201.2.135 50mm x 135 deg muPVC bend
200.2.91
50mm x 91 1/4deg muPVC swept bend
210.2 50mm muPVC straight coupling
204.2.135 50mm muPVC swept tee
Wavin OSMA PVC-C Solvent Weld System (50mm)
Wavin Code
2M073 3M lenght waste pipe 50mm
2M163 50mm x 45 deg bend
2M161 50mm x 87.5 deg bend
2M104 50mm double socket
2M190 50mm x 8.75 tee
The following pipe and ttings are approved.
Consideration MUST be given to expansion and contraction of the ue. Refer to Assembly Practice (Section 2.13) in this
installation and Servicing Instructions for further guidance.
17Installation and Servicing
FLUE OUTLET
Section 2 - Installation

Maximum lengths
Due to the resistance presented by extended ue length a slight reduction in maximum boiler output will occur where combined
ue and air lengths in excess of 18.0 m and 16.0 m (50 mm muPVC) are used. In such cases the boiler output will be reduced
by 0.6% and 0.8% per additional metre.
The maximum lengths of both air inlet pipe and ue outlet pipe, when no bends are used, are as detailed in graphs below.
However, each bend used has an equivalent length that must be deducted from the maximum straight length stated in graphs
below. Knuckle bends must not be tted.
A 92.5º swept elbow is equivalent to 1.0 m straight length. A 45º bend is equivalent to 0.5 m straight length.
It is possible to have variable ue and air lengths as described within the shaded area of graphs below.
2.8 FLUE SYSTEM - CONTINUED
Termination of the ue and air
The ue and air pipes may terminate independently through
any external walls within the same dwelling except on
opposing walls, within the maximum lengths shown in
graph below. (Alternatively a vertical ue pipe termination is
acceptable.)
The air pipe must have an elbow and 150 mm length of pipe
directed downwards with a termination grill tted (unless
adequately sheltered i.e. on a balcony).
The air pipe can be situated at the side or beneath the ue
pipe to a minimum dimension of 140 mm (see diagram
right). It must not be sited above the ue pipe.
The ue and air pipes must extend by at least 40mm from
the wall surface.
Condensing boilers emit a visible plume of water vapour
from the ue terminal, this is normal. It is the responsibility
of the installer to judiciously select a terminal location that
does not cause a nuisance.
If either the ue or air terminal is below a height of 2 m from
ground level a terminal guard must be tted.
Notes. Installations in England above 18 meters requires
a High Rise Flue Kit. This adheres to the new building
regulations. (ADB_Vol1_ Dwellings_2019_edition_inc_2020_
amendments).
TERMINAL POSITIONS
Flue
Pipe Elbow
Minimum Separation
140mm
Acceptable
range of air
pipe siting
Terminal
Air Pipe
150mm
Installations in Scotland above 11 meters requires the High
Rise Flue Kit. This adheres to the new building standards
technical handbook 2020: Domestic Buildings (April 2021
Addendum).
Installations using the approved stainless steel 45° elbow on
the air intake must achieve a minimum separation of 300 mm
horizontally or below the ue pipe. Please refer to instructions
provided with the kit.
Any vertical termination MUST have the terminals tted and
the air intake comply with the dimensions above.
Slope
‘Horizontal’ ue outlet pipework MUST slope at least 1.5 degrees (26 mm per metre run) downwards towards the boiler. Pipework
can be vertical. Only swept elbows can be used.
Air inlet pipework can be truly horizontal or vertical, or sloping in a downward direction towards the boiler but in each case rain, etc.,
must be prevented from entering the pipe. There must be no troughs in any of the pipework, whether it be air inlet or ue outlet.
SCAN
for High
Rise Flue Kit
Instructions
18
Installation and Servicing
FLUE OUTLET
Section 2 - Installation

6m
2m
Bracket at
each 1 metre
1m
4m
1.5m
6m
1.5º back
to boiler
1.5º back
to boiler
Air
Elbows 2 x 1m = 2m
Straights 6+2+0.15 = 8.15m
Total = 10.15m
Overall Flue / Air = 25.65m
Flue
Elbows 3 x 1m = 3m
Straights 4+6+1.5+1 = 12.5m
Total = 15.5m
Calculations
0.15m
Sleeve
2m 2.5m
1.5m
2m
4m
4m
0.15m
3.5m
3.5m
1.5º back
to boiler
Air
Sleeve
1.5º back
to boiler
Bracket every
1 metre
Flue
3 x 90º elbows 3
Straight lengths 2.5
1.5
3.5
4
14.5
Overall Flue / Air = 30.15m
Air
4 x 90º elbows 4
Straight lengths 2
2
3.5
4
0.15
15.65
Calculations
2 4 6 8 10 12 14 16 18 20 22 24 26 28
2
6
10
14
18
22
26
30
Acceptable Operating Area
Keston Combi35 - Flue & Air Pipe Length
Flue Pipe Length [m]
Air Pipe Length [m]
15.65
14.5
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
2
6
10
14
18
22
26
30
34
38
Acceptable Operating Area
Keston Combi30 - Flue & Air Pipe Length
Flue Pipe Length [m]
Air Pipe Length [m]
10.15
15.5
Keston Combi2C30 - Flue &Air Pipe Length
Keston Combi2C35 - Flue &Air Pipe Length
2.9 FLUE INSTALLATION EXAMPLE KESTON COMBI2C30
2.10 FLUE INSTALLATION EXAMPLE KESTON COMBI2 C35
19Installation and Servicing
FLUE OUTLET
Section 2 - Installation

Twin Flue Positions
When Flue & Air Terminals are less
than 500 mm apart
When Flue & Air Terminals are
more than 500 mm apart
Flue min.
spacing Air min. spacing Flue min. spacing Air min. spacing
A Below an opening (1) 300 mm 50 mm 300 mm 50 mm
B Above an opening (1) 300 mm 50 mm 300 mm 50 mm
CHorizontally to an opening 300 mm 50 mm 300 mm 50 mm
D Below gutters,soil pipes or drain pipes 75 mm 75 mm 75 mm 75 mm
E Below eaves 200 mm 50 mm 200 mm 50 mm
F Below balcony or car port roof 200 mm 50 mm 200 mm 50 mm
G From a vertical drain pipe or soil pipe 150 mm 50 mm 150 mm 50 mm
H From an internal or external corner or to a boundary
alongside the terminal (2)
200mm 50 mm 200 mm 50 mm
I Above ground,roof or balcony level 300 mm 100 mm 300 mm 100 mm
J From a surface or boundary facing the terminal 600 mm 100 mm 600 mm 100 mm
K From a terminal facing a terminal 1200 mm 1200 mm 1200 mm 1200 mm
L From an opening in the car port into the building 1200 mm 100 mm 1200 mm 100 mm
M Vertically from a terminal on the same wall 1500 mm 1500 mm 1500 mm 1500 mm
NHorizontally from a terminal on the same wall 300 mm 300 mm 300 mm 300 mm
O From the wall on which the terminal is mounted 40 mm 40 mm 40 mm 40 mm
P From a vertical structure on the roof NA NA 300 mm NA
Q Above intersection with roof NA NA 150 mm NA
,(1) In addition, for temperature and structural reasons, the terminal should not be nearer than 150 mm (fanned draught) to an
opening in the building fabric formed for the purpose of accommodating a built-in element such as a window frame
,(2) The reference to external corners does not apply to building protrusions not exceeding 450 mm, such as disused chimneys on
external walls for: fanned draught appliances
TERMINAL POSITIONS
Flue
Pipe Elbow
Minimum Separation
140 mm
Acceptable
range of air
pipe siting
Terminal
Air Pipe
150 mm
AA
B
A
A = 600 mm
B = 2000 mm
The flue terminal shall not penetrate
the shaded area of the roof
If chimney penetrates dotted area such that
A is less than 300 mm,
B shall not be less than 300 mm.
When running flue pipes vertically
they MUST be a minimum of 140 mm apart
and termination MUST comply with Section 2.3 an 2.6.
150 mm
min
300 mm
min
Pitched roof with structure
Air Terminal with
Termination Grill
Vertical termination must have an
elbow with terminal fitted directed from
roof, 150 mm above roof intersection
with air taken from side wall or low level
(min 500 mm separation).
2.11 FLUE TERMINATION POSITION
20
Installation and Servicing
FLUE OUTLET
Section 2 - Installation