Keston C36P Combi Installation and Servicing Manual

WD388/0/2004 The Keston C36 Combi & C36P Combi Boilers

C

C36

CC

36 Combi

36 36

Modulating Condensing Combination

Gas Fired Boiler

Combi

CombiCombi

User, Installation And Servicing

Instructions

CE/PI No : 87BQ006

C36 Combi - GC No : 47 930 01

C36P Combi - GC No : 47 930 02

These instructions must be left either with

the user or next to the site gas meter.

34 West Common Road

Hayes, Bromley, Kent BR2 7BX

Tel. [phone] Fax. [phone]

email : [e-mail] web : www.keston.co.uk

COMPLIANT WITH BUILDING REGULATION PART L1 & L2

SEDBUK A RATED

WD388/0/2004 The Keston C36 Combi & C36P Combi Boilers

CONTENTS

NB : These instructions are an integral part of the appliance. This document must be handed over to

the user on completion of the installation to ensure compliance with the Gas Safety (Installation
& Use) Regulations

Section Description

0 HANDLING INSTRUCTIONS

0.1 List of contents

0.2 Recommended handling procedure

1 USER INSTRUCTIONS

1.1 Introduction

1.2 Maintenance

1.3 Boiler Setup and Operation

1.4 Safety Information

2 GENERAL INSTRUCTION

2.1 Description

2.2 Boiler Schematic

2.3 Related Documents

2.4 Physical Data

2.5 Optional Accessories

2.6 Performance Data C36 Combi and C36P Combi

3 BOILER LOCATION

3.1 Dimensions & Minimum Clearances

3.2 Service Connections

3.3 Position

3.4 Electrical

3.5 Boiler Size Selection

3.6 Gas Supply

3.7 CH & DHW Water Systems

3.8 Flue System

3.9 Air Supply

3.10 Compartment Installation

3.11 Condensate Drainage

4 INSTALLATION OF THE BOILER

4.1 Wall Mounting Bracket

4.2 Mounting The Boiler

4.3 Assembly Practice

4.4 Installing Flue And Air Pipes

4.5 Condensate Drainage

4.6 Water System

4.7 Gas Supply

4.8 Electrical Supply

4.9 Exchanging A Boiler

5 COMMISSIONING OF THE BOILER

5.1 Initial Flushing

5.2 Gas Supply

5.3 Electrical Installation

5.4 LP Gas

5.5 Initial Firing

5.6 Hot Flushing

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WD388/0/2004 The Keston C36 Combi & C36P Combi Boilers

5.7 Combustion Testing

5.8 Checking The Gas Pressure

5.9 Timing The Gas Meter

5.10 Handing Over To The User

6 FAULT FINDING

6.1 Electrical Control Sequence

6.2 Normal Operation

6.3 Fault Modes

6.4 Functional Flow Wiring Diagram

6.5 Electrical Wiring Diagram

6.6 Illustrated Wiring Diagram

6.7 Exploded Assembly Diagrams

7 SERVICING

7.1 Pre Service Checks

7.2 Recommended Routine Service

8 REPLACEMENT OF PARTS

8.0 General

8.1 Precautions

8.2 Access

8.3 Replacement Procedure

8.4 Electrical Components

8.5 Spark Ignition/Flame Detection Electrode

8.6 Burner

8.7 Heat Exchanger

8.8 Condensate Trap

8.9 Pump

8.10 DHW Heat Exchanger

8.11 Expansion Vessel

9 SPARE PARTS LISTINGS

10 GAS BOILER COMMISSIONING CHECKLIST

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0. HANDLING INSTRUCTIONS

0.1 LIST OF CONTENTS

The Keston C36 Combi and C36P Combi are supplied almost totally pre-assembled. The units
use standard 50 mm muPVC (BS5255 and/or BSEN1566-1 and BSEN1329) pipe for the flue
and air intake systems. The boiler is packed in a single box without additional flue kit. All
additional components are packed inside the boiler cabinet itself. The following is a list of
components and their location in the boiler cabinet

Equipment List
Item Quantity Location

Wall Bracket Rawl Plugs 6 Inside accessories bag
Wall Bracket Wall Fixing Screws 6 Inside accessories bag
Wall Mounting Bracket 1 Secured to inside right

hand side of boiler case

Pre-Installation Jig Locator Cross 1 Secured to inside right

hand side of boiler case
Wall Mounting Bracket Nuts 1 Inside accessories bag.
Wall Mounting Bracket Washers 1+1 Inside accessories bag
50 mm muPVC Air/Flue Terminals 2 Inside accessories bag
Air Inlet Spigot (50 mm) 1 Inside accessories bag
Flue Outlet Spigot (50 mm) 1 Inside accessories bag
Air Inlet Spigot Gasket 1 Inside accessories bag
Air Inlet Spigot + Flue Outlet Spigot M6 Screws 4+2 Inside accessories bag
Cabinet Cable Entry Clamps 2 Inside accessories bag
Gas Isolating Cock with PTN 1 Inside accessories bag
Filling Loop Kit 1 Inside accessories bag

Document List
Item Quantity Location
Registration of Purchase 1 In A4 envelope
Installation Template 1 In document bag

Remove the cabinet shell by removing the two retaining screws in the top of the cabinet and
the two retaining screws in the bottom of the cabinet.

0.2 RECOMMENDED HANDLING PROCEDURE

NB : The following lift operation exceeds the recommended weight for a one-man lift as
specified in the Manual Handling Operations 1992 Regulations.

For the carriage of carton it is recommended at least two people perform any lift. Clear the
carriage route of the carton from point of delivery to point of installation. Take care to avoid trip
hazards, slippery or wet surfaces and when climbing steps and stairs. Always use assistance
if required. If a sack truck is used it is recommended the carton is strapped to the truck.

For the unpacking of the appliance from the carton, it is recommended at least two people
perform any lift. It is recommended to cut the base end of carton and open the carton flaps.
Ensure the protective packing over the boiler tappings at the base of the boiler is kept in place,
then tilt the boiler forwards from its back onto its base and remove carton by sliding up over
the boiler. When lifting this appliance the back should be kept straight at all times. Avoid
twisting at the waist - reposition the feet instead. Avoid upper body bending when holding the
appliance and keep the boiler as close to the body as possible.

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WD388/0/2004 The Keston C36 Combi & C36P Combi Boilers

Before hanging the appliance on the wall it is best to store the appliance laid on its back with
the casing on. When ready to hang the boiler on the wall remove the casing and place to one
side. At this stage it is assumed that the wall bracket is correctly positioned and secured on
the wall face.

a) Have the wall bracket nut and washer to hand so that they can be accessed whilst holding

the boiler in position on its mounting bracket. If the optional pre-installation jig is not being
used discard the Pre-Installation Jig Locator Cross.

b) The boiler has a dry weight of 45 kg (99 lbs) and will therefore require at least two people

to lift without the use of lifting aids - ensure co-ordinated movements durring lift. Always
use assistance if required.

c) Lift the boiler by gripping at the four corners of the boiler back plate. When lifting this

appliance the back should be kept straight at all times. Avoid twisting at the waist ­reposition the feet instead. Avoid upper body bending when holding the appliance and

keep the boiler as close to the body as possible.
d) Lift the boiler and locate onto the stud and the two pegs of the wall mounting bracket.
e) Place the wall mounting bracket washers over the bracket stud protruding through the

back plate of the boiler.
f) Secure the boiler onto the wall bracket by fixing the wall mounting bracket nut onto the

wall bracket stud. This must be tightened well.

Safety footwear and gloves are recommended PPE when lifting this appliance - to protect
against sharp edges and ensure good grip.

The C36 Combi and C36P Combi boilers can be fitted in compartments with very small
clearances required around the appliance (refer to Section 3.1). Due consideration should
therefore be given to access within the compartment for lifting and positioning.

A pre-installation jig plate (part no C.10C.0.11.00.0) with heating flow, heating return and cold
supply isolation is available as an optional accessory. This jig enables the installation of the
pipework to be carried out and pressure tested before hanging the boiler. Further instructions
for this procedure are included with the jig plate kit.

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WD388/0/2004 Chapter 1 : User Instructions The Keston C36 Combi & C36P Combi Boilers

1. USER INSTRUCTIONS

1.1 INTRODUCTION

Thank you for chosing this Keston C36 Combi for your household heating and hot water
needs. The boiler is designed to be very straightforward to operate and has no user
serviceable parts inside the cabinet. The following instructions are to provide you with
information on the operation and maintenance of your C36 Combi and what to do in the
unlikely event of a fault.

These user instructions should be read carefully to ensure safe and economical use of your
C36 Combi. The C36 Combi model is for use with natural gas only, the C36P Combi model is
for use with LPG only.

1.2 MAINTENANCE
Servicing

To ensure continual safe and efficient operation and to maintain product warranties it is a
requirement that the appliance is checked and serviced at least once per year. It is the law
that any servicing must be carried out by a competent person. Removal of the appliance

cabinet by anyone other than a competent person will automatically invalidate the
appliance warranty.

Clearances

If fixtures are to be positioned close to the boiler, the following minimum clearances must be
observed: Top 150mm, Left 5mm, Right 5mm, Base 100mm, Front 305mm. Extended
clearance is required to the front for servicing.

Cleaning

Normal case cleaning only requires dusting with a dry cloth. To remove more stubborn marks
wipe with a damp cloth and finish with a dry cloth.

1.3 BOILER SETUP & OPERATION

Check that the gas supply from the gas meter is turned on. Switch on the electrical supply to
the boiler. The display will now run through a self check procedure. Set any controls to call for
heat.

To light the boiler

The C36 Combi features separate adjustment of central heating and domestic hot water
temperature. To set these press the “+” or “-” buttons associated with the heating or hot water
temperature and set the required temperature. After a few seconds the display stop flashing
and will change back to show the actual boiler temperature.
If the actual temperature is less than the desired temperature the boiler will fire and, after a
few seconds, a “.” will appear in the lower right hand corner of the display to show that the
boiler is alight.
In summer you can switch the boiler to hot water only by pressing the “Summer” button to that
the green lamp above it is illuminated. In this mode the boiler will not respond to any demand
for central heating. Press the “Summer” button again to extinguish the green light above and
resume normal central heating operation.

Normal Operation

During normal operation the digital display will dhow the current boiler temperature and will
show a “.” In the lower right corner of the display when the burner is alight. If the green lamp
near the CH or DHW+ - keys is illuminated the boiler is receiving a demand for that function.
If the green lamp is flashing the boiler is either up to temperature or shutting down following
removal of the CH or DHW demand.

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WD388/0/2004 Chapter 1 : User Instructions The Keston C36 Combi & C36P Combi Boilers

Fault Modes

In the event that the boiler detects a situation which it considers to be a fault the display will
change to show a flashing fault code starting with an “E” and then a two digit number. The
table below explains these codes and the action you should take.

Description of faultDisplay

E01

Ignition failure - the boiler has attempted to light five times and not succeeded - check
the gas supply is on.
False flame - There is possibly a problem with the power supply.E02

E03

Boiler overheat - Check that any valves to the heating circuit have not been shut down,
that there is no air in the system and that the water pressure is correct..

E24

Water pressure losses - You have topped up the water pressure more than 4 times in
24 hours. You may have a leak on the system..

E26

Flame drop out - Check for obstruction of the flue and/or air terminals,
blockage/freezing of the drain pipe or a low gas supply (LPG).
Mains supply voltage < 180V - There may be a problem with your power supplyE34
Mains supply frequency incorrect - There may be a problem with your power supply.E35
Water pressure error - You must top up the water pressure for your systemE37
Water pressure too high - You have put too much water pressure in your systemE40

The above is an abbreviate list of possible error codes. If the code is not in the list above
consult a CORGI registered engineer. A full list of codes can be found in Chapter 6 of this
manual. If a code appears and you feel the original cause has been rectified, press the
“Reset” button to resume boiler operation. If the code persists consult a CORGI registered
engineer.
When topping up the water pressure you can observe the actual pressure by pressing the
“Installer” button repeatedly until the number “5” appears. After a few seconds the display with
then change to show the system water pressure in bar. Set the water pressure to between 1.0
and 2.0 bar.

Precautions

Care must be taken at all times to ensure that no blockage or obstruction is present in the
condensate drainage line. In addition, the air intake and flue exhaust terminals must be free
from obstruction at all times.

Frost Protection

The C36 Combi has an integral frost protection function. However, care should also be taken
that any exposed pipework is adequately insulated to prevent freezing.

1.4 SAFETY INFORMATION

IF YOU SUSPECT A GAS LEAK TURN OFF THE APPLIANCE IMMEDIATELY, TURN OFF
THE GAS TAP TO THE APPLIANCE (LOCATED UNDERNEATH) AND CONTACT YOUR
LOCAL GAS REGION WITHOUT DELAY.

Benchmark Initiative

As part of the industry wide “Benchmark” initiative C36 Combi boiler
manual includes Gas Boiler Commissioning Checklist (Chapter 10). This form should be
completed by your installer at the end of the installation and commissioning process. The
details of the Checklist will be required in the event of any warranty work being required. There
is also Service Interval Record (Chapter 10) to be completed after each annual service visit.

These forms (Chapter 10) should be kept in a safe place for the life of the boiler.

The boiler should be installed and serviced only by CORGI registered operatives. All CORGI
registered Installers carry a CORGI ID card and have a registration number. Both should be

recorded in your boiler manual (Chapter 10: GAS BOILER COMMISSIONING
CHECKLIST). You can check your installer by calling CORGI direct on 01256 372300.

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WD388/0/2004 Chapter 2 : General Instruction The Keston C36 Combi & C36P Combi Boilers

2. GENERAL INSTRUCTION

2.1 DESCRIPTION

The KESTON C36 Combi and C36P Combi combination boilers utilise the latest in
condensing technology to produce a high efficiency boilers that deliver an exceptional hot
water flow rate with SEDBUK A rated efficiency.

The C36 Combi and C36P Combi are unique in concept and design. They comprise a

high efficiency stainless steel heat exchanger coupled with a low emissions burner to

deliver ultra high efficiency condensing mode operation and a plate-to-plate heat

exchanger for domestic hot water production all within a compact wall hung cabinet. The

unit automatically adjusts gas and air rate according to demand to give a heating output in

the range of 7.4kW to 28.0kW [condensing]. The integral pump assembly is automatically

speed controlled to best match water flow rate to heat output & further increase appliance

efficiency. The efficient plate-to-plate heat exchanger provides superior levels of

performance: its has an outstanding hot water performance of 14.5 L/min (at 35C

temperature rise) and 17.0 L/min (at 30C temperature rise - EN625)

In addition, the boilers feature a connection for an optional outside sensor to enable the

boilers inbuilt weather compensation option which delivers enhanced user comfort levels

with peak operating efficiency due to the lower flow temperatures involved. The boiler also

features an “Opentherm” connection point for the Keston Room Control module which

provides further advanced user control for room temperature compensation and optimum

start. The boiler fascia provides separate user controls for central heating and domestic

hot water temperatures. The advanced hot water flow monitoring ensures exceptionally

stable hot water temperatures are provided. The boilers have the added advantage of very

high efficiency, and small diameter muPVC plastic flue which can be extended up to 20

metres horizontally or vertically.

The Keston C36 Combi uses a variable speed combustion blower to deliver a premix of

gas and air to a downward firing burner in a high efficiency, single pass heat exchanger.

The flue system is room sealed and fan powered. The ignition is direct spark and fully

automatic. The boiler housing is not waterproof and should be installed in a position

where it will always be dry. Combustion air is drawn from the cabinet which is connected

to outside atmosphere via a small diameter plastic intake pipe. The cabinet therefore

remains under negative pressure at all times the boiler is operating.

These boilers are designed for use as part of a sealed water central heating system with

fully pumped circulation. The pump, an 8l expansion vessel and associated safety devices

are all fitted within the boiler.

The boiler heat exchanger is made from highly corrosion resistant stainless steel in

corrugated pipe form which provides massive surface area within a compact dimension.

The hot combustion gases from the down firing burner pass around the stainless steel

pipes imparting heat into the system water. The integral variable speed pump within the

appliance cabinet ensures the heat exchanger receives correct water flow when firing.

The C36 Combi is not a high water content boiler and does not contain the metal mass, or

water volume, of a cast iron or steel boiler. This boiler is of low mass and low water

content and therefore responds faster when there is a call for heat. The C36 Combi

features full user diagnostics, integral frost protection function, automatic pump and fan

exercise in periods of inactivity, anti cycle control and dry fire protection.

2.2 BOILER SCHEMATIC

Air is drawn into the boiler through a 50 mm muPVC (BS5255 and/or BSEN1566-1 and

BSEN1329) plastic pipe or, alternatively, via a 75mm Keston composite plastic pipe. Gas

is mixed with combustion air at the inlet to the fan. The gas flow is automatically regulated

by the gas valve according to the air flow generated by the fan. The gas and air are

thoroughly mixed in the blower and fed into the burner located at the top end of the heat

exchanger module. The gas and air mixture is ignited by a direct spark ignition control

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WD388/0/2004 Chapter 2 : General Instruction The Keston C36 Combi & C36P Combi Boilers

system and burns with
a blue flame just off
the surface of the
burner. As the hot
products of
combustion pass
downwards, they are
cooled by exchanging
heat with the
circulating water which
enters the heat
exchanger at the
bottom of the heat
exchanger. The
optimum heat input is
detected by monitoring
flow and return
temperatures and is
adjusted by controlling
the speed of the fan.
The optimum pump
speed is also detected
and automatically
selected by the boiler.

When the return water temperature is below 55oC, part of the water vapour in the
combustion products will condense inside the heat exchanger, thus increasing the boiler
efficiency further by releasing
the latent heat of
condensation. This
condensate falls to the
bottom of the heat exchanger
where it is separated from
the flue gases and exits from
the boiler through the
condensate drain. Any
condensate formed in the
flue runs back down the
flueway and is drained at the
base of the flue connection
to the heat exchanger or
drain points within the flue.

The condensate is very
slightly acidic (about the
same acidity as vinegar) and
should be piped in a plastic
pipe. It is not harmful to the
waste disposal system and
may be disposed of as
normal waste water.

The flue gases are piped in a
50 mm muPVC (BS5255
and/or BSEN1566-1 and
BSEN1329) plastic or,
alternatively, 75mm Keston
composite plastic pipe to
outside. The temperature of
the flue gases are usually

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WD388/0/2004 Chapter 2 : General Instruction The Keston C36 Combi & C36P Combi Boilers

around 5oC to 10oC above the temperature of the return water. The flue pipe should be

terminated outside the building from where they cannot re-enter the building or any other

adjacent building.

The heating level may be controlled by room thermostats, programmer time clocks and

compatible energy management systems. An optional Keston room controller can be

connected which will provide enhanced controls such as room compensation to further

increase efficiency and comfort levels. Once the controls are set the boiler operates

automatically. Further, a Keston outside sensor can be connected to the boiler which will

automatically invoke weather compensated heating which further boosts user comfort and

boiler efficiency.

In the event of the boiler overheating the safety devices will cause a safety shutdown. A

safety discharge valve and discharge pipe is fitted to the boiler.

The C36 Combi features an integral frost protection function which will operate the pump,

regardless of the external controls, should the boiler temperature fall below 10oC. In the

event the boiler temperature falls below 5oC the boiler will also fire. This is to avoid

damage to the boiler through freezing of boiler water. The boiler will turn off when the flow

temperature exceeds 15oC.

The C36 Combi features an integral pump exercise function which will run the pump,

without firing the boiler, for 10 seconds in the event the boiler is on standby for in excess

of 24 hours without firing. This is to help prevent seizing of the pump due to long periods

of inactivity.

2.3 RELATED DOCUMENTS

The Keston C36 Combi and C36P Combi Combination Condensing Boiler must be

installed in accordance with the current issue of the Gas Safety (Installation and Use)

Regulations 1996, current IEE Wiring Regulations, Building Regulations, Building

Standards (Scotland) Consolidation, and the Bye Laws of the local Water Undertaking. It

is the law that ALL gas appliances are installed by a competent person in accordance with

the above regulations.

In addition, due account must be taken to the following Codes Of Practice:

BS 6891 : Gas Supplies
BS 6798 : Installation Central Heating Boilers
BS 5449 : Installation Pumped Central Heating
BS 5546 : Installation Domestic Hot Water
BS 5440.1 : Flues
BS 5440.2 : Air Supply
BS 5482.1 : Domestic Propane and Butane Burning

BS 7074.1 : Expansion Vessels
BS 7593 : Treatment of Water in Hot Water Central Heating

BS 7671 : Requirements for Electrical Installations. IEE

For Timber Framed Buildings, British Gas Publications DM2. Also British Gas
Publications 'Guidance Notes For The Installation Of Domestic Gas Condensing
Boilers' and 'Specification For Domestic Wet Central Heating Systems'.

Installations

Systems

Wiring Regulations 16th Edition.

In IE, the installation must be carried out by a competent person and installed in

accordance with the current edition of IS813 “Domestic Gas Installations”, the current

Building Regulation and reference should be made to the current ETC1 rules for electrical

installations.

No alterations should be made to the boiler without written permission from Keston Boilers

Ltd. Any unauthorised modification will invalidate the warranty and may affect the safe and

efficient operation of the boiler.

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WD388/0/2004 Chapter 2 : General Instruction The Keston C36 Combi & C36P Combi Boilers

2.4 PHYSICAL DATA - C36 COMBI & C36P COMBI

Cabinet Height mm 840
Cabinet Width mm 450
Cabinet Depth mm 300
Top Clearance mm 150
Side Clearance mm 5
Base Clearance mm 100
Front Clearance (for servicing) mm 300
Weight - Full kg / (lbs) 50/(110)
Weight - Empty kg / (lbs) 45/(99)
Flow and Return Connection (using pre-installation jig) 22mm Compression
DHW and CWS Connection (using pre-installation jig) 15mm Compression
Gas Connection 15mm Compression
Condensate Connection overflow 22mm plastic
Safety Valve Connection discharge 15mm copper
IP Rating IP20 (IPX0)
Flue and Air Intake Material 50mm muPVC (BS5255 and/or BSEN1566-1 and BSEN1329)
Flue Pipe Size (nominal bore) mm / (in) 50 / (2)
Air Intake Pipe Size (nominal bore) mm / (in) 50 / (2)
Max. Air Intake Length m 39
Max. Flue Outlet Length m 20*
Max. Total Flue Outlet and Air Intake Length m 40
* Flue lengths between 16 and 20m will create a 1% reduction in DHW output.
Flue and Air Intake Material 75mm Keston Composite
Flue Pipe Size (nominal bore) mm / (in) 75 / (3)
Air Intake Pipe Size (nominal bore) mm / (in) 75 / (3)
Max. Air Intake Length m 117
Max. Flue Outlet Length m 60**
Max. Total Flue Outlet and Air Intake Length m 120
** Flue lengths between 48 and 60m will create a 1% reduction in DHW output

2.5 OPTIONAL ACCESSORIES

A range of accessories are available from Keston Boilers Ltd to compliment an installation.
Terminal wall sealing collars are available to make good the external all face whilst working from
the inside of the building using 50mm muPVC (BS5255 and/or BSEN1566-1 and BSEN1329)
pipe. Stand-off frames are available to leave a 50mm gap behind the boiler to allow routing of
pipes behind the boiler.

Description Part Number

Pre-Installation Jig Plate C.10C.0.11.00.0
Flue Terminal Wall Sealing Collar (50mm) C.08.0.00.07.0
Air Terminal Wall Sealing Collar (50mm) C.08.0.00.07.0
50/75mm Flue Adapter C.17.2.00.60.0
Flue Outlet Terminal (75mm) C.17.2.26.00.0
Air Inlet Terminal (75mm) C.17.2.26.00.0
Stand Off Back Plate C.10C.0.01.00.0
Outside Temperature Sensor C.10C.0.09.00.0
Keston Chronotherm Room Controller C.17.4.21.00.0

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WD388/0/2004 Chapter 2 : General Instruction The Keston C36 Combi & C36P Combi Boilers

2.6 PERFORMANCE DATA - C36 COMBI & C36P COMBI

C36 COMBI C36P COMBI
Nat. Gas (G20) LPG (G31)

Min. Input (Gross CV) kW/(Btu/h) 8.3/(28,300) 8.1/(27,600)
Max. CH Input (Gross CV) kW/(Btu/h) 28.3/(96,500) 27.7/(94,500)
Max. DHW Input (Gross CV) kW (Btu/h) 40.0/(136,500) 39.0/(133,000)
Max. DHW Output to Water kW/(Btu/h) 36.0/((122,800) 36.0/(122,800)
Max. CH Output To Water

(80/60oC Flow/Return) kW/(Btu/h) 25.2/(86,000) 25.2/(86,000)
(50/30oC Flow/Return) kW/(Btu/h) 28.0/(95,500) 27.7/(94,500)

Min. CH Output To Water

(80/60oC Flow/Return) kW/(Btu/h) 7.4/(25,250) 7.4(25,250)
(50/30oC Flow/Return) kW/(Btu/h) 8.2/(28,000) 8.1/(27,600)

Max. Domestic Hot Water Flow Rate litre/min 14.5 14.5

(at 35OC Rise)
Specific DHW Rate (30OC Rise) litre/min 17.0 17.0
Min. Domestic Hot Water Flow Rate litre/min 0.35 0.35
Max. Domestic Hot Water Flow Temp.OC 65 65
Max. Burner Press.-Hot (Factory Preset) mbar/(in w.g) 0/(0) 0/(0)
Max. Gas Cons. After 10 mins (DHW) l/s / (Ft3/hr) 1.03/(131) 0.48/(61)
Max. Operating Flow Temp.

o

C 82 82
Max. Press. (Sealed System) bar 2.50 2.50
Inlet Gas Pressure mbar/(in w.g) 20.0 / (8.0) 37.0/(14.8)

Recommended Temp Diff.

o

C 8 to 20 8 to 20
Electrical Supply 230V 50Hz 230V 50Hz
Power Consumption (Max) W 180 180
Power Consumption (Standby) W 6 6
Type of Gas G20 Natural Gas G31 LPG
Optimum Flue Gas CO2 Level (at max CH rate, case on) 9.3 10.6
Expected CO/CO2 Ratio (at max CH rate, case on) 0.0006 0.001
Destination Countries GB/IE GB/IE
SEDBUK Efficiency 90.7 92.8
NOx Class 5 5
Safety Valve bar / (lbf/sq in) 3 / (43.5) 3 / (43.5)
Expansion Vessel Capacity litre 8 8
[NB: For larger systems an additional expansion vessel may be required]
Expansion Vessel Charge Pressure bar / (lbf/sq in) 1.0 / (14.5)
Heating System Minimum Pressure bar / (lbf/sq in) 0.6 / ( 8.7)
DHW Max. Working Pressure bar / (lbf/sq in) 8/ (116)
Min. Working Pressure for Max. Domestic Flow Rate bar / (lbf/sq in) 2
Maximum CWS Inlet Temperature

o

C 50 50

Seasonal Efficiency (SEDBUK) =90.7 (C36 Combi) & 92.8 (C36P Combi)
This 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 Advantica Technologies Ltd

Keston Boilers Ltd declare that there are no substances harmful to health within the
appliance or used during the production of the appliance.

The C36 Combi is intended for domestic and commercial EMC environments and on a
governed G20 meter supply.

The C36P Combi is intended for domestic and commercial EMC environments and on a
governed G31 supply.

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WD388/0/2004 Chapter 2 : General Instruction The Keston C36 Combi & C36P Combi Boilers

This boiler meets the requirements of SI 3083 The Boiler (Efficiency) Regulations and is therefore
deemed to meet the requirements of Directive 92/42/EEC. The CE mark on the appliance shows
compliance with Directives 90/396/EEC, 73/23/EEC and 89/336/EEC.

IMPORTANT
This product contains ceramic fibre boards, which although not regarded as a risk, contain
ceramic fibre which may cause temporary irritation to eyes, skin and respiratory tract. The
fibres are held in place by inorganic binders. Therefore as long as the boards are not
disturbed they will not be released. Since the boards are non-servicable parts there should
be no risk. Under no circumstances should the user interfere with any sealed parts.

To ensure that the release of fibres from these RCF articles is kept to a minimum, during
installation and servicing we recommend that you use a HEPA filtered vacuum to remove
any dust accumulated in and around the appliance before and after working on the appli­ance. When replacing these articles we recommend that the replaced items are not broken
up, but are sealed within heavy duty polythene bags, and clearly labelled as RCF waste.
RCF waste is classed as a stable, non-reactive hazardous waste and may be disposed at a
landfill licensed to accept such waste. Protective clothing is not required when handling
these articles, but we recommend you follow the normal hygiene rules of not smoking,
eating or drinking in the work area and always wash your hands before eating or drinking.

Benchmark Initiative

As part of the industry wide “Benchmark” initiative C36 Combi boiler
manual includes Gas Boiler Commissioning Checklist (Chapter 10).
This form should be completed by your installer at the end of the installation and commissioning
process. The details of the Checklist will be required in the event of any warranty work being
required. There is also Service Interval Record (Chapter 10) to be completed after each annual
service visit.

These forms (Chapter 10) should be kept in a safe place for the life of the boiler.

The boiler should be installed and serviced only by CORGI registered operatives. All CORGI regis­tered Installers carry a CORGI ID card and have a registration number. Both should be recorded
in your boiler manual (Chapter 10: GAS BOILER COMMISSIONING CHECKLIST). You can
check your installer by calling CORGI direct on 01256 372300.

IN THE EVENT OF A GAS LEAK

Turn off the gas isolation valve to the property immediately. Extinguish
all naked flames or other sources of ignition. Do not operate electrical
switches on or off. Open all doors and windows to ventilate the area.

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WD388/0/2004 Chapter 3 - Boiler Location The Keston C36 Combi & C36P Combi Boilers

All dimensions in mm.

3. BOILER LOCATION

All dimensions in mm.

150

3.1 DIMENSIONS AND MINIMUM
CLEARANCES

The boiler must be installed in minimum
clearances shown to allow subsequent
servicing, and safe operation. However, larger
clearances may be required during installation.

3.2 SERVICE CONNECTIONS

Without Optional Pre-Installation Jig:
Gas, water, air and flue pipe, condensation,
and electrical connections are as shown. Gas :
15mm compression. Flow/Return 0.75BSPM
compression. DHW/CWS 0.5BSPM
compression.
With Optional Pre-Installation Jig:
Gas, water, air and flue pipe, condensation,
and electrical connections are as shown. Gas :
15mm compression. Flow/Return 22mm
compression. DHW/CWS 15mm
compression.

An optional stand-off frame is also available
which mounts behind the boiler to leave a
50mm deep space behind the boiler. This is
to permit pipe routing behind the boiler if
required. See Section 2.5 - Optional
Accessories.

3.3 POSITION

The C36 Combi and C36P Combi are not
suitable for external installation. The boiler
may be installed in any room or internal
space, although particular attention is drawn
to the requirements of the current IEE Wiring
Regulations and, in Scotland, the electrical
provisions of the Building Regulations

Figure 3.1.2
Dimensions

Flue

Air Intake

300 When servicing appliance
10 When appliance is operating

Figure 3.1.1

100

450

Minimum Clearances

0

0

3

55

840

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WD388/0/2004 Chapter 3 - Boiler Location The Keston C36 & C36P Combi Boilers

applicable in Scotland, with respect to the installation of the boiler in a room or internal
space containing a bath or shower.
Where a room-sealed appliance is installed in a room containing a bath or shower, 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. The C36 Combi and C36P
Combi are classified as IP20 (IPX0) and are therefore suitable for installation in Zone 3
areas, unless subject to hose down.
Compartment installation is permitted - such compartments must be constructed in
accordance with BS 6798.
The wall on which the boiler is mounted must be of suitable load bearing capacity and
must be non-combustible.
The Keston C36 Combi can be located virtually anywhere desired provided that all

[NB: Refer to
Section 3.8.3]

regulations are complied with. Because of the boiler's compact size and venting flexibility,
the installation is not limited to a boiler room setting. Before locating the boiler near a living
space consider whether the sounds generated by the boiler will be objectionable. The
boiler may be located within a cupboard enclosure to reduce noise levels if located within
a living space. LPG boilers must not be installed in a cellar.

3.4 ELECTRICAL

3.4.1 Electrical Connections

The boiler must be connected to a permanent 230V ~ 50Hz supply, fused at 3A.

The boiler has provision to receive a 230VAC switched live signal from a
room thermostat/time clock. Alternatively, a Keston Room Controller can be
connected directly, via two core low voltage cable, to the terminals marked
“OT”. The Keston Room Controller will then provide fully room
compensated control to ensure the boiler output is matched to the rooms
requirements at optimum boiler efficiency. DHW demand will always take
priority over heating demand. Wiring external to the boiler must be in

accordance with current I.E.E wiring regulations and local regulations.

Chimneys not used for
venting any other

appliance may be used.

Secure air & flue pipes at
chimney outlet.

Figure 3.3

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WD388/0/2004 Chapter 3 - Boiler Location The Keston C36 Combi & C36P Combi Boilers

The method of connection to the mains electricity supply must facilitate complete
electrical isolation of the boiler, preferably by the use of a fused, unswitched three
pin plug and a shuttered socket-outlet, both complying with the requirements of
BS 1363. There must be only one common method of isolation for the boiler and
its control system.
The appliance must be connected to the 3A supply via a fused double-pole switch
having at least 3 mm (1/8 inch) contact separation in both poles, serving only the
boiler and the system controls.
The connection point to the mains supply should be readily accessible and
adjacent to the boiler, except for rooms containing a bath or a shower. Refer to
section 3.3 Position.

3.4.2 External Wiring & Controls

1. The boiler is designed so that all control wiring is external to the boiler.

2. Heating control signal inputs must the 230VAC "switched live" type unless
using a Keston Room Controller (see below)

3.4.2.1 Enhanced Control Options

Room Compensation (Opentherm)
A Keston Room Controller may be used to provide room compensated
control to ensure the boiler output is matched to the rooms requirements
at optimum boiler efficiency

Mains Supply
Fused @ 3A

230V

3.4.2 Wiring Example

Weather Compensation
A Keston outside temperature sensor may be connected as an option.
The boiler will automatically detect this connection and will operate on a
"weather compensation" basis when receiving a heating demand signal
from the SL terminal or from a Keston Room Controller. Screened cable
(80% density) must be used to connect the outside temperature sensor.

3.5 BOILER SIZE SELECTION

The C36 Combi will automatically adjust heat output and pump speed to match the
system requirements at any given time. Efficiency and combustion levels are maintained
at optimum levels throughout the possible output range. The C36 Combi is therefore
suitable for all systems with a total heat load within the maximum range of the boiler.

Live

Neutral

Earth

L
N
E

SL

OTC
OTC

OT
OT

KESTON
C36 Combi

1

Room Thermostat

2

T6360B1028

3

To Keston
Ext. Sensor
[Optional]

To Keston
Room Controller
[Optional - instead of room thermostat]

3.6 GAS SUPPLY

A gas meter should be connected to the service pipe by the local gas region or their
contractor. An existing meter should be checked preferably by the gas region to ensure
that the meter is adequate to deal with the rate of gas supply required. Installation pipes
should be fitted in accordance with BS 6891.

Minimum/Maximum Gas Pressure:

Natural gas pressure before the gas valve must be maintained at between 18 mbar (7.2 in
WG) and 22 mbar (8.8 in) while the boiler is running

.
LPG pressure must be maintained between 31.5 mbar (12.4 in w.g) and 37.6 mbar (14.8
in w.g) while the boiler is running.

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WD388/0/2004 Chapter 3 - Boiler Location The Keston C36 & C36P Combi Boilers

Gas pressures above or below these levels will lead to problems associated with the gas
valve's internal pressure regulator.

Supply pipes to the boiler must not be sized less than the boiler inlet connection
(15 mm). Due consideration must be given to the supply pressure to other gas
appliances in the premises. Reduction in dynamic gas supply pressure will result in
intermittent ignition failures. Ensure gas supply pipe work is adequately sized for
the length of run from the meter to the boiler at a supply rate of 40kW (i.e. a natural

gas supply should be considered to be a minimum of 22mm diameter, reducing to 15mm
at the boiler. If gas runs greater than 12m, including the allowance for bends, are involved
the pipe size should be increased further).

3.7 CH & DHW WATER SYSTEMS

All piping must be installed in accordance with all applicable local and Water Supply
Bylaws for forced hot water heating systems.
Consideration must be given to pipe capabilities and pressure drop through the piping
when selecting pipe sizes. The primary pipe connections to the boiler must be sized
according to the system load, not dictated by the boiler connection sizes.
Water treatment must be carried out to BS 7593 : Treatment of Water in Hot Water
Central Heating Systems.
In IE the requirements given in the current edition of IS813 and the current Building
Regulations must be followed.

a The Keston C36 Combi is designed for installation on sealed water systems only.

With fully pumped water circulation. The pump, an 8l expansion vessel and
associated safety devices are fitted within the boiler.

b Any system must be thoroughly flushed clean of grease, dirt and debris, prior to

connection with the boiler. A trap may be installed in the flow line to collect any
solder, or other debris, from the installation.

c All water systems must be constructed to comply with requirements of the Local

Water Authority.
d Always use a system complying with the requirements of BS 5449 and BS 6798.
e System design must ensure an open circuit is always available to ensure

circulation when the pump overrun function is operating after boiler shutdown.
f Isolation valves must be fitted on the cold mains supply, the heating flow and the

heating return to enable isolation when maintaining the boiler. Such isolation

valves are included in the optional pre-installation jig (C.10C.0.11.00.0)
g Copper tubing to BS 2871 Part 1 or barrier plastic pipe suitable to 110 oC, such as

Unipipe, is recommended.
h Jointing should be either with capillary, threaded or compression fittings. Pipes

should have a gradient to ensure air is passed easily to vent points and water

flows readily to drain points.
i Draining taps must be located in accessible positions which permit the draining of

the boiler. Draining taps should be at least 22 mm in nominal size and be in

accordance with BS 2879. A drain tap is incorporated into the optional

pre-installation jig (C.10C.0.11.00.0)

AIR VENT POINTS
j These must be fitted at all high points where air will naturally collect and must be

sited to allow complete draining of the system.

Table 3.7 Additional Expansion Vessel Selection

Safety Valve Setting
Vessel charge & initial system

3.0 bar

1.0 bar

pressure.
Total Water Content of system in
excess of 125 litres
25 litres
50 litres
75 litres
100 litres
125 litres

Vessel
Volume

2.7

5.4

8.2

10.9

13.6

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WD388/0/2004 Chapter 3 - Boiler Location The Keston C36 Combi & C36P Combi Boilers

k. The boiler is supplied with an integral expansion vessel of 8l capacity. This is

suitable for systems of up to 125 Litres system volume. Table 3.7 Expansion
Vessel Selection provides guidance for the correct additional expansion vessel
size to use for systems with a water content larger than 125 Litres. Any additional
vessel must be fitted on the boiler primary return.

l A filling point must be fitted, in accordance with local water authority

requirements. An approved filling loop is supplied loose with the boiler installation
jig. There must be no permanent connection to the mains water supply. The filling
loop must therefore be left isolated at both ends and disconnected after the
system is filled.

m The installation must be designed to work with flow temperatures of up to 110 oC.

All components of the system must be suitable for a working pressure of 3 bar
and a temperature of 110 oC. Care should be taken in making all connections that
the risk of leakage is minimised.

n The pipe from the safety discharge valve must not discharge above an entrance,

window or any type of public access area. The boiler safety discharge valve pipe
must be extended using not less than 15mm pipe to discharge, in a visible
position, outside the building, facing downwards, preferably over a drain. The
pipe must have a continuos fall and be routed to a position so that any discharge
of water, possibly boiling, or steam cannot create any danger to persons,
damage to property or external electrical components or wiring. To ease future
servicing it is advisable to use a compression type fitting to extend the safety
discharge valve pipe.

DOMESTIC WATER

DOMESTIC HOT WATER

COLD WATER SUPPLY

3.7.1 Boiler By-pass Piping

Boiler water flows are critical to the operation of the boiler. If flow cannot be maintained
through the system piping to meet the minimums required by the boiler, insufficient water
flows through the boiler will cause the boiler to "kettle" or even produce steam which can
damage the heat exchanger and will invalidate the heat exchanger warranty. In addition,
an open circuit is required after boiler shutdown to permit circulation during the boilers 2
minute pump overrun sequence.
It is advisable to incorporate a boiler by-pass in the system, especially if thermostatic
radiator valves are used. The flow/return differential should be 10oC to 20oC. To comply

with the Building Regulations Part L1 the bypass must of the automatic type.

KESTON
COMBI

Expansion
Vessel
(if required)

By-pass
(if required)

Drain
Cock

Isolating Valve

Figure 3.7 : CH & DHW Sealed Systems Diagram

RETURN

HEATING CIRCUIT

FLOW

Isolating & Dbl Chekc Valve

Flex Hose
(disconnected
after filling)

3.7.2 Air Elimination

In the initial charge of water to the boiler system and in all subsequent additions of water
to the system some air will be dissolved in the water. As the water is heated the air is

Installation & Servicing Instructions Page : 13