Keston 50 - GC, 80 - GC, 60 - GC, 50, 80 Installation And Servicing Instructions

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Fan Powered High Efficiency Condensing Gas Boiler

Installation And Servicing Instructions

Keston 50 - GC No 41 930 01 Keston 60 - GC No 41 930 02 Keston 80 - GC No 41 930 03

PI No. : 87AQ306

These instructions must be left either with the user or next to

the household gas meter.

34 West Common Road

Hayes, Bromley, Kent BR2 7BX

Tel. (44)0208 462 0262 Fax. (44)0208 462 4459

WD50/2/1997 The Keston 50, 60 & 80 Condensing Boilers

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CONTENTS

Section Description 1 GENERAL INSTRUCTION

1.1 Description

1.2 Boiler Schematic

1.3 Related Documents

1.4 Performance Data

1.5 General Data

2 BOILER LOCATION

2.1 Dimensions & Minimum Clearances

2.2 Service Connections

2.3 Position

2.4 Electrical

2.5 Boiler Size Selection

2.6 Gas Supply

2.7 Water Systems

2.8 Flue System

2.9 Air Supply

2.10 Compartment Installation

2.11 Condensate Drainage

2.12 Radiant Floor Heating

2.13 Low Water Volume Boiler vs. Cast Iron Boiler

2.14 Determine Radiation Needed Room-By-Room

3 INSTALLATION OF THE BOILER

3.1 Wall Mounting Bracket

3.2 Mounting The Boiler

3.3 Assembly Practice

3.4 Installing Flue And Air Pipes

3.5 Condensate Drainage

3.6 Water System

3.7 Gas Supply

3.8 Electrical Supply

3.9 Exchanging A Boiler

4 COMMISSIONING OF THE BOILER

4.1 Initial Flushing

4.2 Gas Supply

4.3 Electrical Installation

4.4 LP Gas Conversion

4.5 Initial Firing

4.6 Hot Flushing

4.7 Checking The Gas Pressure

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4.8 Timing The Gas Meter

4.9 Handing Over To The User

5 FAULT FINDING

5.1 Electrical Control Sequence

5.2 Fault Finding Flow Chart

5.3 Continuity Checking

5.4 Functional Flow Wiring Diagram

5.5 Electrical Wiring Diagram

5.6 Illustrated Wiring Diagram

5.7 Exploded Assembly Diagrams

6 SERVICING

6.1 Pre Service Checks

6.2 Recommended Routine Service

7 REPLACEMENT OF PARTS

7.1 General

7.2 Precautions

7.3 Access

7.4 Electrical

7.5 Gas Orifice

7.6 Spark Ignition/Flame Detection Electrode

7.7 Burner Head & Burner

7.8 Heat Exchanger

7.9 Air Filter

7.10 Condensate Trap

7.11 Pressure Gauge

7.12 Sight Glass

7.13 HT Ignition Lead

7.14 Air Vent

7.15 Air Orifice

8 SPARE PARTS LISTINGS

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1. GENERAL INSTRUCTION

1.1 DESCRIPTION

The Keston Condensing Boiler is unique in its concept and des ign. While the application for which the boiler was designed is the same as those which other boilers are us ed the Keston boiler has the added advantage of very high efficiency, and small diameter plastic flue which can be extended to 10 metres horizontally or vertically.

The Keston uses a high power combustion blower to deliver a pre-mix of gas and air to a downward firing burner in a high efficiency, single pass heat exchanger.

Normally the combustion temperature of the air gas mixture is around 1800

C but the

Keston achieves combustion at an amazing 1000

C thereby reducing the NOx emissions

down to an incredible less than 5 p.p.m. The flue system is room sealed and fan powered. The ignition is direct spark and fully

automatic. The boiler housing is not waterproof. The boiler should be installed in a position where it will always be dry. A small air intake point is incorporated within the appliance cabinet to ensure that the interior of the c abinet is maintained under a slight negative pressure. This is a safety feature to ensure no products may leak out of the cabinet into the installation space.

The boiler is suitable f or connection to open vented or sealed system s. The s ystem mus t be pumped central heating or pumped central heating with combined indirect domestic hot water. Gravity circuits must not be used.

The boiler has a primary heat exchanger which, through its combustion chamber and corrugated coil, transfer s the heat produced in the hot gases of combustion pr ocess into the circulating water. Head characteristics of the boiler coil must be taken into consideration when calculating the pump size.

The Keston boiler 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. This f eatur e requir es a higher water pumping rate through the boiler otherwise localised boiling will occur within the boiler.

Allow a pressure drop through the boiler of 3.2 ft head and a water flow of 4.2 gallons (19 litres) per minute f or the Keston 50, 4.3 ft head and 5 gallons (23 litres) per m inute for the Keston 60 and 9 ft head and 6.7 gallons (30.5 litres) per minute for the Keston 80.

The boiler selected m ust be sized relative to the total c alculated heat loss of the building. The boiler rated output should not be greater than the total required to make up the calculated heat loss plus the heat required to provide domestic hot water. If there are special conditions such as excessive domestic hot water usage consult the manufacturer.

1.2 BOILER SCHEMATIC

Air is drawn into the boiler through a 40mm ( BS5255) m uPVC pipe. T he air f low is proved by a differential pressure across the air control orifice.

Gas is mixed with com bustion air at the inlet to the fan. T he gas flow is regulated by an orifice located in the housing downstream of the gas valve.

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WD50/2/1997 Chapter 1 : General Instruction The Keston 50, 60 & 80 Condensing Boiler

Installation & Servicing Instructions

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Figure 1.2 Boiler Schematic

LEGEND

1 Heating Return 2 Water Return Thermostat 3 Downstream Pressture Test Nipple 4 Flame Ignition/Sensing Probe 5 Burner 6 Automatic Air Vent 7 High Limit Thermostat 8 Heating Flow 9 Flue Exhaust 10 Air/Gas Flexible Connector 11 Air Filter 12 Air Inlet Flexible Connector

13 Ignition Control Box 14 Gas Low Pressure Switch 15 Gas Multifunctional Control 16 Gas Inlet Flexible Connector 17 Air Pressure Switch 18 Combustion Bl ower 19 Condensate T rtap 20 Flue Overheat Thermostat 21 Heat Exchanger 22 Flow Overheat Thermostat 23 Water Low Pressure Switch 24 Combustion Test Point

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The gas and air are thoroughly mixed in the blower and fed into the bur ner located at the top end of the heat exchanger module. The gas and air m ix ture is ignited by a direct spark ignition control system and burns with a blue flame j ust off the surface of the burner. As the hot products of com bustion pass downwards, they are cooled, exchanging heat with the circulating water which enters the heat exchanger coil at the bottom of the heat exchanger.

When the return water temperature is below 54oC, part of the water vapour in the combustion products will condense inside the heat exchanger , thus increasing the boiler efficiency. This condensate f alls to the bottom of the heat exchanger where it is separ ated 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.

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 40m m m uPVC pipe to the outside. The temperatur e of the flue gases are usually less than

10oC above the temperature of the retur n water. The flue

pipe should be terminated outside the building from where they cannot re-enter the building or any other adjacent building or cause a nuisance by pluming.

The heating level may be controlled by room thermos tats, hot water cylinder thermostats and programmer time clocks.

1.3 RELATED DOCUMENTS

The Keston Condensing Boiler must be ins talled in accordance with the current issue of the Gas Safety (Ins tallation and Use) Regulations, c urrent IEE W iring Regulations, Safety

document no. 635 - The Electricity At Work Regulations 1989, Building Regulations, Building Standards (Scotland) Consolidation, and the Bye Laws of the local Water Undertaking.

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 & Butane Burning Installations BS 7074.1 : Expansion Vessels BS 7593 : Treatment of Water in Hot Water Central Heating

Systems

BS 7671 : Requirements for Electrical Installations. IEE Wiring

Regulations 16th Edition.

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'.

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1.4 PERFORMANCE DATA

Keston 50 Keston 60 Keston 80

10 to 1510 to 1510 to 15

CRecommended Temperature

Differential

3.432.712.38mmGas Orifice Size

8.08.08.0in. w g

20.020.020.0mbarInlet Gas Pressure

8.0

8.08.0

2.5

2.5MMinimum Head (Open Systems)

2.702.702.70BarMaximum Pressure (Sealed Systems)

100.0100.0100.0Ft

30.5030.5030.50MMaximum Head (Open Systems)

80.0080.0080.00

CMaximum Operating Flow

(CV of Gas - 38.7 MJ/m3) (1038 Btu/Ft

)

89.1165.854.43Ft

/HrRunning

0.70.510.43L/SGas Consumption After 10 mins

3.943.542.36in w.g.

(FACTORY PRESET)

1096mbarBurner Setting Pressure (Hot)

88,80065,00054,000Btu/h60

C Flow 40oC Return

2619.215.8KWBoiler Output To Water

80,00060,00050,000Btu/h80

C Flow 60oC Return

23.5 17.514.7KWBoiler Output To Water

92,50068,30056,500Btu/h

27.119.916.6KWBoiler Input

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1.5 GENERAL DATA

Keston 50 Keston 60 Keston 80

3.30 litres2.35 litres2.35 litresWater Content

Rear panel inside caseRear panel inside caseRear panel inside caseData Badge Posn

50 kg (110 lbs)44 kg (97 lbs)44 kg (97 lbs)Weight - Empty

52 kg (114 lbs)46 kg (101 lbs)46 kg (101 lbs)Weight - Full

5 Amps5 Amps5 AmpsExt. Fuse Rating

175 W140 W140 WPwr Consumption

230V 50Hz230V 50 Hz230V 50 Hz Power Supply

28 mm Copper28 mm Copper

28 mm

Copper

Return Connection

28 mm Copper28 mm Copper

28 mm

CopperFlow Connection

0.5 inch BSPT Male (15mm to gas cock)

Gas Supply Connection

Keston FilterKeston Filter Keston FilterFilter

Tridelta FS 6717 - 1428Tridelta FS 6717 - 1428Tridelta FS 6717 - 1428Air Pressure Switch

Full Sequence ControlFull Sequence ControlFull Sequence ControlIgnition

RAM ElectronicsRAM Electronics

RAM

Electronics

Direct Spark

0.18 KW 2900 RPM0.18 KW 2900 RPM0.18 KW 2900 RPM

Type LPB 102 220/240Type LPB 102 220/240Type LPB 102 220/240

KestonKestonKestonCombustion Fan

36E Series36E Series36E Series

White RogersWhite RogersWhite Rogers Gas Control

Keston PremixKeston PremixKeston PremixMain Burner

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2. BOILER LOCATION

2.1 DIMENSIONS AND MINIMUM CLEARANCES

The boiler must be installed in minimum clearances shown to allow subsequent servicing, and safe operation.

2.2 SERVICE CONNECTIONS

Gas, water, air and flue pipe, condensation, and electrical connections are as shown. Gas : 0.5 inch BSP male. Flow/Return : 28 mm

copper.

2.3 POSITION

The Keston is 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 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

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Installation & Servicing Instructions

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All dimensions in mm.

254

305

127

Figure 2.1.1 Minimum Clearances

All dimensions in mm.

500

Figure 2.1.2 Dimensions

712 (Kest on 50 & 60)

Air Intake

Flue

Return

Flow

890 (Keston 80)

Top View

Base View

Service Connection Locations

All dimensions are in mm.

405

237

181

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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.

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.

Important : It is not recommended to install the boiler on a studded wall or similar - it is possible that the vibration from the fan would be amplified and transmitted to other parts of the house.

Chimneys not used for venting any other

appliance may be used.

Figure 2.3

Secure air & flue pipes at chimney outlet.

[NB: Refer to Section 2.8.3]

The Keston can be located virtually anywhere desired provided that all regulations are met. 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. Sound levels from the boiler are no greater than from any other type of high-efficiency boiler but even minimal levels may be objectionable if located near a bedroom or in a living area.

2.4 ELECTRICAL

2.4.1 Electrical Connections

The boiler must be connected to a 230V ~ 50Hz supply, fused at 5A. All external controls and wiring must be suitable for mains voltage. Wiring

external tothe boiler must be in accordance with current I.E.E wiring regulations and local regulations.

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The method of connection to the mains electricity supply must facilitate complete electrical isolation of the boiler complying with the requirements of BS

1363. The appliance must be connected to the supply via a fused double-pole switch,

having at least 3mm (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 2.3 Position.

2.4.2 External Wiring & Controls

1. The boiler is deisgned so that all control wiring is external to the boiler. Hence, any programmers or room thermostats etc must act by switching the 230V supply to the boiler.

2. System designs which allow the boiler to fire when there is no pumped circulation must NOT be used.

3. A programmer may be used with zone valves to give independent control of central heating and hot water.

2.5 BOILER SIZE SELECTION

The size of the boiler to be used is determined by the total calculated heat loss of the building. Match the calculated heat loss with the boilers rated output. If a boiler is

installed with an output rating greatly exceeding the total capacity of the distribution system the efficiency of the boiler will be reduced. If the boiler is to be used to heat

domestic hot water no additional capacity is normally needed for the average residential installation since there is usually some excess capacity in the boiler as water heating is an intermittent load.

2.6 GAS SUPPLY

A gas meter should be connected to the service pipe by the local gas supplier 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 Natural Gas Pressure:

Natural gas pressure before the gas valve must be maintained at 20 mbar (8 in w.g) while the boiler is running. Gas pressures above or below this level will lead to problems associated with the gas valve's internal pressure regulator.

Minimum/Maximum L P Gas Pressure:

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

. 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.

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A gas cock is supplied loose with the boiler. This cock should be fitted in the gas line to the boiler as close to the boiler as possible so that it is easily identified as the cock to isolate the boiler.

2.7 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. Water treatment must be carried out to BS 7593 : Treament of Water in Hot Water Central Heating Systems. Pump isolating valves must be positioned as close to the pump as possible.

a The Keston is suitable for use on open, vented water systems with combined feed

and vent.

b It is preferable for use on sealed water systems, provided the appropriate

components required (see Section 2.7.2 Sealed Systems) are included in the system.

c 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.

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

Water Authority.

e Only fully pumped systems can be used - gravity systems are strictly

not

suitable.

f Always use a system complying with the requirements of BS 5449 and BS 6798. g The system must be so arranged that there shall always be a minimum flow of 4.2

gpm (19 litres/min) [Keston 50], 5 gpm (23 litres/min) [Keston 60] or 6.7 gpm (30.5 litres/min) [Keston 80] when the boiler is firing. This can be via a specially installed by-pass arrangement.

h Copper tubing to BS 2871 Part 1 is recommended. i Jointing should be either with capillary or compression fittings. Pipes should have

a gradient to ensure air is passed easily to vent points and water flows readily to drain points.

j Draining taps must be located in accessible positions which permit the draining of

the boiler and hot water storage vessel. Draining taps should be at least 15 mm in nominal size and be in accordance with BS 2879. AIR VENT POINTS

k These must be fitted at all high points where air may collect.

2.7.1 Open Vented Systems

A typical system is shown in Figure 2.7.1 which includes a combined feed and vent. Note there must be no valve between the boiler flow and the open vent. Note that the minimum static head required is 8 ft at the boiler flow pipe. If the cold feed/vent is not brought to the flow pipe as shown, then the pressure loss across the heat exchanger may have to be taken into account when estimating the static pressure.

Although suitable for open vented systems with combined feed and vent arrangements, the Keston is a low water content boiler. As such, any air entrainement within the system water will produce boiler "kettling". It is therefore recommended, if in any doubt, to consider the use of sealed

systems where possible.

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2.7.2 Sealed Systems

Sealed systems must be designed in accordance with BS 5449 and BS 7074 Pt1. A typical sealed system is shown in Figure 2.7.2. It must include :

(i) A safety valve fitted on the flow, adjacent to the boiler. It must be non

adjustable and preset to 3 bar. A drain pipe must be attached, at least as big as the valve connection, and routed to drain in any area not hazardous nor where it may be subject to freezing.

(ii) An expansion vessel complying with BS 4814 and sized in accordance

with the requirements of BS 5449 and BS 7074 Pt 1. The vessel must be

positioned on the inlet to the pump. (iii) A filling point, in accordance with local water authority requirements. (iv) A method of system make-up (automatic or manual), in accordance with

local water authority requirements. (v) There must be no permanent connection of mains water to the boiler

system. (vi) The installation must be designed to work with flow temperatures of up to

110

All components of the system including the heat exchanger of the indirect cylinder must be suitable for a working pressure of 3 bar and a temperature of 110

C. Care should be taken in making all connections that the risk of leakage is

minimised.

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Installation & Servicing Instructions

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Boiler

Rad. 2 Rad. 1

Pump

Expansion Pipe

Expansion Tank

Minimum 8ft Height

Cylinder

Figure2.7.1 : Open Vented System Diagram

Keston

3 Way Valve

Strainer

By-pass Bal. Valve

L/S

22mm pipe

(minimum)

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2.7.3 Hot Water System (if applicable)

The hot water storage vessel must be of the indirect type (certain direct cylinders can be used provided

they are suitably adapted by fitting an immersion calorifier). DIRECT CYLINDERS MUST NOT BE USED. Further guidance is provided in BS 1394. It is advisable to fit a lockshield valve on the cylinder return

to enable balancing of flow rate through the cylinder.

2.7.4 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 (see paragraph 2.7 (g)). 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.

It is normally advisable to incorporate a boiler by-pass in the system, especially if thermostatic radiator valves are used. The by-pass should be fitted with a lockshield valve to permit balancing of the by-pass flow rate. The flow/return differential should be 10

C to 15oC. The lockshield valve can be adjusted to

maintain this condition with the radiators fully heated.

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Installation & Servicing Instructions

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Valve

Boiler

Figure 2.7.2 : Sealed System Di agram

Keston

Pressure Gauge

Expansion Vessel

Double Check Valve

Pump

Air Vent

Make -up vessel. Max. capacity of 3 lt. (5pt)

Non-Return Valve

Auto Air Vent

Hose Union bib tap

Hosepipe (disconnected after filling)

Hose Connector

BS 1010:2 Stop Tap

Test Cock

Drain Cock

HEATING CIRCUIT

RETURN

FLOW

Strainer

Safety Relief

By-pass

Bal.

Valve

L/S

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2.7.5 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 driven out of the solution and will collect in high spots in the system. These air bubbles can interfere with pumping and heat transfer and

must be eliminated.

Installation of air bleed valves at the high spot(s) in the system will allow for air elimination when filling the system and will allow re-venting in a day or so after all air has been driven out of solution. Installation of an automatic air vent will ensure that any air, even minute amounts, which subsequently enters the system will be automatically removed.

2.7.6 Strainers

Debris in the heating system can cause noise if it enters the heat exchanger. Fitting of a Y-strainer ahead of the circulating pump will trap any debris left in the system and will protect the pump from damage.

2.7.7 Pump Selection

The Keston boilers have low water content heat exchangers with a high resistance to flow, when compared with cast iron heat exchanger boilers. As a result selection of the correct pump is essential

in order to avoid localised boiling within the heat exchanger. The selected pump must be capable of maintaining the required flow rate for the boiler against the pressure losses contributed by the boiler and the rest of the system.

Refer to the pressure loss/flow rate Table 2.7.7 to determine the pressure loss from the boilers. Add this to the pressure loss caused by the rest of the system and select a pump capable of meeting the flow rate required at the total pressure loss generated by the boiler and the rest of the system. The selected pump must comply with BS 1394.

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Installation & Servicing Instructions

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Y-Strainer will collect any loose debris in the piping.

Figure 2.7.6 Strainers

Figure 2.7.7 : Pressure Loss Graph

10 15 20 25 30

0.5

1.0

1.5

2.0

2.5

3.0

Water Flow - L/min

Pressure Loss - m

3.5

4.0

4.5

Keston 50 Keston 60

Keston 80

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It is important to note that the minimum flow rate must be maintained whenever the boiler is firing. Systems using zone valves must be specifically designed to only fire the boiler when the pump is running and the minimum flow rate can be achieved.

The Wilo Salmson Gold Star pump, or the Grundfoss 15/60 pump is normally suitable for use with the Keston condensing boiler range. However, in all cases due consideration must be given to the resistance to flow offered by the rest of the system when making a final pump selection. This is particularly important when using small bore underfloor

heating pipework.

Table 2.7.7 Pump Selection

2.8 FLUE SYSTEM

2.8.1 Design

Individual air supply and flue outlet pipes are used. The material used for flue outlet &/or air inlet must be muPVC to BS 5255 and of an internal diameter of 38 mm.

Both flue outlet terminal and air inlet terminal are supplied and are illustrated in Figure 2.8.1.

2.8.2 Maximum Lengths

The maximum lengths of both air inlet pipe and flue outlet pipe, when no bends are used, are as detailed below.

Maximum Air Inlet Length : 10.0 m Maximum Flue Outlet Length : 10.0 m

However, each bend used has an equivalent length that must be deducted from the maximum straight length stated above.

A 92.5

sweep elbow is equivalent to 1.0m straight length. Example: Air inlet uses two 92.5o sweep elbows. Hence, maximum length permissible (ie

a+b in figure 2.8.2) = 10.0m - 1.0m - 1.0m = 8.0m Flue outlet uses one 92.5

sweep elbow. Hence, maximum length permissible (ie

c+d in figure 7 = 10.0m - 1.0 m = 9.0m

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9.0 ft

2.75m

27.5 kPa

4.3 ft

1.3m

13 kPa

3.2 ft

0.97m

9.7 kPa

Pressure Loss Through Boiler

6.7 GPM

30.5 litres/min

5.0 GPM

22.7 litres/min

4.2 GPM

19.1 litres/min

Min Flow Rate Required

Keston 80Keston 60Keston 50Boiler Model

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2.8.3 Slope

'Horizontal' flue outlet pipework MUST slope at least 2.5 degrees (45 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 this 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 flue outlet. If a 45

mm per meter slope is not possible, contact Keston Boilers Technical Department for further guidance.

Due the low temperature of the flue gases further condensate will form within the flue system. Drain points, with suitable traps, must therefore be incorporated within the flue system at the base of vertical flue sections in excess of 2m. These additional condensate drains must be run to discharge as detailed in section 2.11. Such drain points can be formed using standard muPVC fittings. Refer to the example in

Figure 2.8.3.

2.8.4 Terminations

It is not advisable to terminate air

intake or flue within a car port area.

Air inlet terminals must be facing upwards and positioned to ensure only fresh air is drawn into the boiler directly from outside the property. The flue outlet terminal is designed to face outwards but can, if desired, be adapted to face in any direction BUT

must not be directed in the region of the air inlet. The two terminals are subject to the requirements of BS 5440 Pt 1 for clearances from features of the building although some can be decreased to the values indicated. If either the air inlet or the flue outlet terminate at a height of less than 2m (6ft) above ground level the termination must be protected by a suitable guard. The K4 terminal guard, manufactured by Tower Flue Components Ltd, is suitable for this purpose and can be obtained from Keston Boilers. The Keston Condensing Boiler, as with any condensing boiler, will generate a condensate "plume" from the flue terminal in all weather conditions.

Consideration must therefore be given to the effect of this "plume" when selecting a location for the flue terminal.

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FLUE

AIR

Figure 2.8.2 : Flue & Air Maximum Length Example

Keston

6 in min.

Figure 2.8.3 :

Flue Condensate Drain Point Example

40mm Tee Fitting

To Boiler

To Terminal

Page 18

It is advisable for horizontal flue terminals to place a 45o elbow at the end of the flue to direct the condensate plume up and away from the property.

Table 2.8.4 Minimum Flue Terminations & Air Inlet Dimensions

2.8.5 Clearances From Wall

Flue outlet and air inlet termination must be at least 60 mm and 95 mm respectively from the wall face.

2.8.6 Distance Between Flue Outlet & Air Inlet

There is no maximum - the terminations can be on opposite sides of the dwelling if desired.

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300300L Horizontally from terminal on same wall.

1.51.5K Vertically from terminal on same wall.

1001.2J From opening in a car port.

1.21.2I From terminal facing a terminal.

100600H From surface facing a terminal

100300G Above ground or balcony or roof.

50600F From internal or external corner.

5075E From vertical drain or soil pipes.

50200D Below balconies.

50300C Below eaves.

7575B Below gutters, soil pipes, drain pipes.

50300A Below openable window, air brick, etc.

Air

Inlet

Flue

Terminal

Dimensions (mm)

Flue Outlet Terminal

Air Intake Terminal

ure 2.8.1 : Terminals

O43

170

O43

O67

Page 19

A minimum clearance of at least 350 mm must be left between the terminations.

2.8.7 General Installations

All parts of the system must be constructed in accordance with BS 5440 Part 1, except where specifically mentioned in these instructions. All pipework must be adequately supported. All joints other than push-on or plastic compression connectors must be made and sealed

with solvent cement suitable for muPVC pipes and conforming to BS 6209: 1982. External wall faces and any internal faces of cavity walls must be made good.

2.9 AIR SUPPLY

The Keston is a room sealed appliance and therefore does not require purpose provided ventilation for combustion air.

2.10 COMPARTMENT INSTALLATION

Where the appliance is installed in a cupboard or compartment, no air vents are required. The boiler will run sufficiently cool without ventilation.

2.11 CONDENSATE DRAINAGE

Being a condensing boiler, the Keston is fitted with a condensate trap at the base of the heat exchanger and flue assembly, with facility to connect to a drain point underneath the appliance.

Use only plastic piping and do not reduce below 22mm internal diameter within the dwelling. Condensate should preferably be drained into the house sanitary waste system or, alternatively, the rainwater system. Termination of the pipe must be either at a branch or stack internal to the house, or externally at an open gully. Alternatively, discharge into a purpose made condensate soakaway can be considered. Existing or purpose built drains must use suitable corrosion resistant material as condensate is mildly acidic.

A minimum slope downwards towards the drain of 2.5

(45mm fall in 1m) is essential. Freezing of the termination and pipework must be prevented. Any drainage pipes outside the house must be at least 32 mm inside diameter.

Further guidance is given in the British Gas Publication 'Guidance Notes for the Installation of Domestic Gas Condensing Boilers'.

2.12 RADIANT FLOOR HEATING

This type of heat distribution creates an exceptionally evenly heated environment and since it is hidden beneath the finished flooring does not interfere with furniture placement. The homeowner has complete freedom to decorate without having to contend with any heating equipment visible in the homes interior. The low operating temperatures of this type of system lead to very good operating efficiencies. In fact, under floor heating can produce in excess of 95% operating efficiency from a Keston condensing boiler. Water temperatures in radiant floor heating systems must be kept relatively low, generally under 48

C, so that surfaces do not become uncomfortably warm to the touch. If radiant heating is only one application for a multi-zone system which also requires higher delivery water temperatures for other zones (i.e. water heating, skirting heaters etc.) then the radiant floor zone temperature will need to be controlled separately from the boiler.

If radiant floor heating is the only application of the boiler, the boilers temperature limits can be lowered accordingly by introducing an external thermostat control mounted on the return pipework into the boiler. This thermostat can then be used to interrupt power

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Page 20

supply to the boiler when the required temperature is reached. Mixing valves are also

available which will mix return water from the system with boiler output water to dilute the temperature of water transmitted to the distribution system. Mixing valves may create problems with low flow and high temperatures through the boiler unless care is taken to design a system which will provide proper flows and will fully load the boiler. Keeping the boiler's temperature high will prevent the boiler from operating at peak efficiencies. Systems which maintain boiler temperatures in this way should be avoided.

If only a portion of the boiler's available output is to be used for radiant floor heating a thermal storage tank will improve the boiler's operation and give adequate control of temperature for the distribution system. By heating water to be distributed to the radiant floor zone to the proper temperature in an indirect-fired water heater, full load conditions will be available to the boiler because the heat exchanger in the tank can be sized to match the boiler's output. The tank's thermostat can be set at the optimum operating temperature needed by the distribution system and short-cycling of the boiler will be prevented. In such insulations it is advisable to calibrate the thermal store's operating thermostat to become the controlling thermostat of the boiler, ie the thermal store operating thermostat is always activated to shut off the boiler before the boilers own thermostat is activated. An insulated thermal storage tank without the heat exchanger may also be used.

2.13 LOW WATER VOLUME BOILER VS. CAST IRON BOILER

Because of their high water content and mass of metal, cast iron and steel boilers are less responsive but somewhat more forgiving of design errors. Short-cycling of the burner on the temperature limit control is less pronounced, though no less detrimental to operation, because the boiler itself will absorb and radiate a significant amount of heat. Low water volume boilers respond more quickly to a call for heat, can be made more compact and lightweight, but must have adequate heat delivery systems to avoid short-cycling of the burner on the temperature limit control. The heat delivery system's output must be equal to or greater than the boiler's output to fully load the boiler or short-cycling will occur.

Likewise, pumping rates of water through low water volume boilers must be maintained so that water is moved through the boiler fast enough so as not to reach boiling temperatures. The slower the water moves through the boiler the more heat it will absorb and the higher the temperatures will rise. Consequently, the pump selected must be adequate to maintain that critical flow of water.

2.14 DETERMINE RADIATION NEEDED ROOM-BY-ROOM

A radiator or convector's ability to deliver heat is related to the water temperature and the rate of delivery to the unit. Most systems in the past have been rated at about 80

C. Higher efficiencies can be gained from a condensing boiler if ratings published at lower temperatures are used. However, this is not imperative. With normal 80

C ratings used a condensing boiler will still deliver significantly higher efficencies than a non-condensing boiler. Lower water temperatures in the system tend to increase the efficiency of the boiler and will help assure that the boiler is subjected to a sufficient load to avoid short-cycling.

The Keston boilers are capable of temperatures of up to 80

C but the higher the temperature of the return water, the lower the efficiency of the system. This is true of all boilers, though all non-condensing boiler must be kept at higher temperatures to avoid condensation in the boiler which destroys such boilers quickly. Materials used in the Keston are made to withstand the condensates corrosive nature.

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Page 21

3. INSTALLATION OF THE BOILER

Read Chapter 2 - Boiler Location and decide upon the position of the boiler. Installation of the boiler is straightfor ward but consideration m ust be given to access to allow flue

and air pipes to be pushed through walls and ceilings. The order in which the components are installed will depend upon particular site conditions, but in general it will be easiest and most accurate to install the boiler and then build up the flue outlet and air inlet pipes to the terminal this is the sequence described.

3.1 WALL MOUNTING BRACKET

a Place the bracket on the wall

horizontally with the pre-drilled holes at the bottom.

b Drill through the centre hole of

the bracket, plug the hole and fix in position.

c Using a spirit level make sure

the bracket is completely level and mark the position of the other screw holes.

d Remove the bracket and drill the

holes in the positions marked. Plug these holes.

e Screw the bracket to the wall

using screws of an appropriate size for the wall type (No. 12 x 2 inch wood screws normally suffice).

f Mark the bottom fixing hole and

drill for a No 8 x 1 inch wood screw. Insert plug.

3.2 MOUNTING THE BOILER

a Lift and locate the upper rear lip on the boiler to the boiler wall bracket. b Move the boiler sideways to centralise the boiler on the bracket. c Screw in the lower fixing screw.

3.3 ASSEMBLY PRACTICE

Remove all plastic debris and burrs when installing air intake piping. Plastic filings caused by cutting muPVC pipe must not be allowed to be drawn into the filter or combustion air blower. Prevent dust entering the air intake when cutting on building sites. Blower failure which is determined to be caused by plastic filings or other debris will not be covered by guarantee.

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All dimensions in mm.

Figure 3.1 Wall Mounting Fixing Locations

110

285

250

Page 22

Combustion air filters are fitted to the Keston condensing boilers as standard. This filter must be examined at least once every year, and more often in particularly dusty and dirty areas.

The combustion air filter will prevent plugging of the burner caused by dirt being trapped in the burner's outer mesh. The filter element supplied with the boiler is obtainable from Keston Boilers or its distributors.

3.4 INSTALLING FLUE AND AIR PIPES

Remember the flue pipe must

slope downwards back towards the boiler and this is best

achieved using 92.5

bends.

a From the two connections on the boiler, mark the positions of the two holes for

the flue and air pipes on the wall(s) or ceiling. To allow access to drill the holes it may be necessary to temporarily remove the boiler. If the boiler stays put then it is imperative that the front panel and top access plate are replaced and the two plastic pipes capped off whilst drilling. Under no circumstances must debris from the wall or cut pipes be allowed to enter the appliance or the plastic pipework.

b Drill the two holes in the wall/ceiling, preferably using a core drill.

3.4.1 Diameter of holes.

i) Allowance must be made for

socketed lengths if these are to be passed through the holes :

du = unsocketted

diameter

= 43 mm

ds = socketed

diameter

= 50 mm

ii) For 'horizontal' runs of flue

pipe the holes must either be oversized or cut at a 5

slope (the latter may be difficult on long holes).

3.4.2 Oversizing

For every 1m length of run, L, the minimum diameter of the horizontal hole, D, must be du + 10 mm or ds + 10 mm respectively, assuming the pipe touches the wall at points T otherwise D will have to be increased by clearance from T. See Section 3.4.3 - Examples.

3.4.3 Examples

a. Wall Depth L = 750 mm

Unsocketted pipe du = 43 mm Diameter hole D = 43+{(

750

1000

)X10} = 43+7.5 = 50.5 mm

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Flue Pipe

Page 23

b. Wall depth L = 2.3 m

Socketed Pipe ds = 50 mm Diameter Hole D = 50+{2.3x10}

= 50+23 = 73 mm

c. Measure, cut and check the air and flue pipes to pass to the exit from the

wall(s) or ceiling.

Always thoroughly deburr all pipes and, most important, remove shavings from within the pipe.

d. Assemble, using adhesive, the pipework from the boiler connections to

the exit from the first wall/ceiling (remount the boiler if removed). When pushing pipe through walls, ensure grit and dust is not allowed to enter the pipe. Ensure pipes are fully engaged into sockets. Connect the condensate drainage system and fill the condensate trap by pouring water down the boiler flue spigot ( See Section 3.5 Condensate Drainage).

Make the final connection of flue and air pipe to the boiler using push on, or plastic compression couplings. Ensure that the connectors

are set vertically otherwise leakage of condensate may occur which will corrode the casing. Do not use adhesive on the 'push on' end of the connecting couplings.

e. Using the same methods drill any further holes (always covering existing

pipework), cut and assemble the pipework.

f. From outside, complete the two terminations - See Section 2.8 Flue

System and make good all holes.

g. Support any pipes whose route could be displaced either of its own

accord or by accident. Any horizontal run over 1m or vertical runs of any length must always be supported.

h. Check all connections for security and re-seal any joints using sovent

cement where soundness may be in doubt. Note: It is equally important to seal the air inlet with solvent cement as

the flue outlet pipe joints.

3.5 CONDENSATE DRAINAGE

Connect the condensate drainage system to the boiler. It is advisable to use a detachable fitting at connection to the boiler to enable easy removal for servicing.

Fill the condensate trap by pouring water into the boiler flue spigot until water is seen to flow freely from the condensate drainage system. Make the final connection of flue pipe to the boiler.

Details are provided in Chapter 2 - Section 2.11 Condensate Drainage Connection : 22 mm plastic pipe.

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Fully Engaged

Adhesive

Page 24

3.6 WATER SYSTEM

Connect the flow and return pipework to the boiler. Ensure a detachable coupling is used at connection to the boiler (ie compression fitting) to enable heat exchanger removal if required. Details of system requirements are given in Chapter 2 - Section 2.7 Water Systems.

Connections : 28mm copper

3.7 GAS SUPPLY

Connect the gas supply to the appliance. Details of gas supply requirements are given in Chapter 2 - Section 2.6 Gas Supply.

Connections : 0.5 inch BSP male. (15mm connection to gas cock).

3.8 ELECTRICAL SUPPLY

The entry point for the electrical supply cable is in the base of the appliance (see Section

2.2 Service Connections fig. 2.1.2) via a cordgrip bush. Feed the cable through this bush and route inside the cabinet to the connection strip located to the front bottom right of the cabinet.

1. The electrical supply must be as specified in Chapter 2 - Section 2.4 Electrical Supply.

WARNING : THIS APPLIANCE MUST BE EARTHED.

2. All external controls and wiring must be suitable for mains voltage. Wiring should be in 3 core PVC insulated cable not less than 24/0.2 mm (0.75mm) to BS 6500 Table 16.

3. The supply connection must be via a 5 amp fused double pole switch, serving only the boiler and system controls. (Refer to Chapter 2 - Section 2.4 Electrical Supply).

4. Securely tighten the terminal screws and route the cable through the re-openable cable clips. Ensure all cables are secured and that the cord grip bush is tightened to securely grip the main cable at entry to the cabinet.

The mains cable must be connected to the terminals as follows:-

N - Blue wire (Neutral) L - Brown wire (Live)

- Yellow/Green Wire (Earth)

Ensure connection is made such that if the cable slips in its anchorage the current carrying conductors become taut before the earthing conductor.

3.9 EXCHANGING A BOILER

Before removing an existing boiler add Fernox Supafloc , or equivalent cleaning agent, in accordance with the manufacturers instructions. Open all radiator valves and fire the boiler. When the system is fully heated, shut off the gas supply and drain down the central heating system.

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Important The Keston condensing boiler contains components which could be damaged or blocked by grease, dirt or solder etc. It is essential that sludge or scale is removed from an existing system.

Connect the new boiler as instructed in this manual and fit in accordance with Sections

3.1 to 3.8 For sealed systems, fill to a pressure of about 2.7 bar. Check the complete system for

water soundness. If leaks need to be rectified using flux or solder the system must be flushed cold again before proceeding.

Reduce the pressure to the Initial System Design Pressure for sealed systems, if applicable. Vent the system.

Gas Supply

The complete gas installation up to the boiler service cock must be checked for soundness. BS 6891.

Electrical Installation

Carry out preliminary electrical safety checks, i.e. Earth continuity, Polarity, Resistance to Earth, Short Circuit using a suitable test meter.

Initial Firing Checking The Gas Pressure At The Burner Pressure Test Nipple

The gas burner pressure must be checked at the burner pressure test nipple (Figure 5.7.3 item 54). Full details of this procedure are given in Section 4.7 Checking The Gas Pressure.

The gas pressure setting is factory adjusted to within the required range and should not normally need re-adjustment. If the reading is incorrect

then check such factors as soundness of the air and flue pipe joints, pressure sensible joints and the gas inlet pressure (20 mbar required). If all joints are sound and the gas inlet pressure is satisfactory set the gas pressure to the required

pressure.

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Burner pressure Adjustment

Burner pressure test nipple.

GAS VALVE

Page 26

4. COMMISSIONING OF THE BOILER

Important: This condensing boiler c ontains components which could be dam aged or block ed by grease, dirt, solder etc., from the water system. The following commissioning procedures must be followed precisely.

4.1 INITIAL FLUSHING

All waterways within the Keston are either copper or high alloy stainless steel. As a result standard water treatment chemicals for conventional central heating boilers are suitable. In any event reference must be made to BS 7593 : Treatment Of Water In Hot Water Central Heating Systems.

a. Disconnect the boiler from the system at the flow and return connections and

temporarily

link the flow and return pipes on the system.

b. Flush the entire system until clean water is discharged, free from dirt, flux, solder

etc. The use of a flushing chemical is recommended, e.g. Fernox Supafloc. Sludge and scale must be removed from an existing system.

c. Connect the system to the boiler and fill in accordance with Section 2.7 - Water

Systems. At this stage, for sealed systems, fill to a pressure of about 2.7 bar.

d. Check the complete system for water soundness. If leaks need to be rectified

using flux and solder, the system must be flushed cold again before proceeding.

e. Reduce the pressure to the Initial System Design Pressure for sealed systems, if

applicable. Vent the system

4.2 GAS SUPPLY

The complete gas installation up to the boiler service cock must be checked for soundness. BS 6891.

4.3 ELECTRICAL INSTALLATION

Carry out preliminary electrical safety checks, i.e. Earth continuity, Polarity, Resistance to Earth, Short Circuit using a suitable test meter.

4.4 LP GAS CONVERSION

All Keston condensing boilers are built and shipped as natural gas fired units. Field conversion kits are available to convert Keston condensing boilers to use LPG. Suitable instructions are supplied with the LPG field conversion kits.

4.5 INITIAL FIRING

Important Checking the gas pressure to the pre-mix burner requires a special procedure, outlined below, which must be carried out.

a. Purge the gas supply in accordance with BS 6891. b. Turn the gas service cock OFF. c. Loosen the screw in the burner pressure test point (Figure 5.7.3 item 106A) on

the gas valve and attach a suitable gauge.

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Page 27

d. Turn on the electrical supply, setting any external controls to call for heat. e. ON/OFF switch - select 'ON'. The amber 'run' light will illuminate on the ON/OFF

switch, the red 'lockout' light will illuminate, the blower and pump will start and, after about 15 seconds, a spark will attempt to light gas at the burner. With the gas service cock off, the boiler will go to lockout - red light illuminated, but the blower and pump will continue to run. At intervals of approximately 1 minute the boiler will make two further attempts to fire. After the final attempt the blower will run for a further 20 seconds before shutting down.

f. Vent the water system.

Important:

The

Keston heat exchanger consists of a single coil which can trap an air pocket. Great care must be taken to ensure that water flow has been established through the heat exchanger and thus ensuring no air pockets remain in the heat exchanger and pipe work. Firing the boiler while an air pocket exists in the heat exchanger could damage it.

g. Note the reading on the pressure gauge caused by the suction of the blower. This

should be approximately minus 12 mbar for the Keston 80, minus 26 mbar for the Keston 60 and minus 32mbar for the Keston 50. If it is not, check the system as follows:

If the negative pressure exceeds the required figure, then it suggests that there is a possible restriction in the air inlet pipework.

If the negative pressure is less than required figure, then it suggests that there is a possible restriction in the flue outlet pipework. Note the

exact reading. h. Turn the gas service cock to ON. i. Turn off the electricity supply, wait 10 seconds and turn back on. The boiler will

again go through its ignition sequence but this time the main burner will light, provided all air has been purged from the gas supply to the boiler. When the burner is lit and the boiler is operating normally the the green (run) lamp, the upper lamp adjacent to the flame symbol, will also be illuminated indicating successful ignition.(If it does not, air is indicated - turn off and repeat the procedure).

If this does not occur, the green (run) lamp, the upper lamp adjacent to the flame symbol, will be extinguished and, at approximately 1 minute intervals, the

electronic ignition system will make two further attempts to light the burner. If the ignition is successful and the boiler is operating normally, the green (run)

lamp, the upper lamp adjacent to the flame symbol, and the red (lockout) lamp will be illuminated simultaneously.

If, after three automatic attempts, the boiler still fails to ignite, the green (run) lamp, the upper lamp adjacent to the flame symbol, will be extinguished and the

red (lockout) lamp will remain illuminated. If, after five manual attempts (to allow for purging of any air in the gas line), the

boiler still fails to ignite (indicated by the red (lockout) lamp) refer to Section 5.2 Fault Finding Flow Chart.

j. Check for gas soundness between the gas service cock and connection to the

burner manifold.

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4.6 HOT FLUSHING

a. Allow the system to heat up,

checking for water soundness.

b. Follow instructions provided with

the cleaning agent, ie Fernox Supafloc. Turn off the boiler and flush the water system while still hot. Thoroughly flush the system with clear water.

c. Refill the system using a quality water treatment such as Fernox MB1 or Fernox

Super Concentrate. If aluminium radiators are used then Fernox Copal should be used. For sealed systems, fill to the required Initial Design Pressure.

4.7 CHECKING THE GAS PRESSURE

With the boiler running measure the burner pressure at the burner pressure test nipple. The gas setting is factory adjusted to within the required range and should not normally

need re-adjustment unless the unit has also been converted to LPG as part of the installation. If the reading is incorrect then check such factors as soundness of the air and flue pipe joints and the gas inlet pressure (20 mbar required). If all joints are sound and the gas inlet pressure is satisfactory remove the brass dust cap covering the burner pressure adjustment screw on the gas valve (See fig. 4.7). Set the gas pressure to the required value as stated in table 1.4 by turning the exposed burner pressure adjustment screw (clockwise will increase burner pressure, anti-clockwise will decrease burner pressure). Replace the brass dust cap to cover the burner pressure adjustment screw.

4.8 TIMING THE GAS METER - NATURAL GAS

Table 4.8 Meter Timings

After the boiler has been started, and with no other appliances using gas, time the gas meter to be certain that the unit is running at the proper gas input. Determine the cubic feet of gas passing through the meter and determine the input in Btu per hour. Input must be within plus or minus 5% of the rated input.

Time, in seconds, the time taken to pass 2 cubic feet of gas through the meter (ie one revolution of a 2 cu ft dial) or 0.1 cubic metres if the meter is of the new metric digital type. Refer to table 4.8 to determine the input to the boiler and the time required for 2 ft

(or

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Burner pressure Adjustment

Burner pressure test nipple.

GAS VALVE

Fig 4.7

1011 btu/h per ft

NB:

152.3686.384,300Keston 80

203.9115.563,018Keston 60

236.2133.854,400Keston 50

Seconds For 0.1 m

Of Natural Gas

Seconds For 2 ft

Of Natural Gas

Btu/h Input RequiredModel

Page 29

0.1m3) of natural gas. Adjust the gas valve screw clockwise to increase the input (speed up the meter) or anticlockwise to decrease the input(slow down the meter) accordingly.

4.9 HANDING OVER TO THE USER

It is important to fully explain the following : a. Procedure to light and turn off the boiler, including isolation of the electrical supply

if necessary.

b. The function of the lockout feature must be explained :

If the red light only is illuminated for more than four minutes, this means that the boiler has failed to light. Turn off the electrical supply and wait 20 seconds. Turn ON again and wait. i) If lockout recurs immediately then the gas supply should be checked as

ON, otherwise consult a Service Engineer.

ii) If it is not possible to relight, the boiler must be isolated and a Service

Engineer called in to rectify the fault. c. Advise that a reduction in the water pressure reading on the gauge for sealed

systems indicates a leak which should be rectified before further use.

d. Advise that the appliance should be serviced by a competent person at least once

a year.

e. Advise on frost precautions. f. Hand over User Instructions.

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Page 30

5. FAULT FINDING

5.1 ELECTRICAL CONTROL SEQUENCE

When the external controls are calling for heat, power will be fed to the boiler connection strip at terminals L (Live) and N (Neutral). If the ON/OFF switch is also in the ON position the boiler ON lamp (amber) will be illuminated. Provided all temperature thermostats and pressure switches are closed, power will be fed to pin 2 on the control box, initiating the following sequence.

(1) The boiler lockout lamp (red) will be illuminated (2) The fan will start. (3) When the fan reaches running speed, the Air Pressure switch, normally open, will

close which will start the ignition sequence.

(4) After a pre-purge period of about 15 seconds, the gas valve will open to allow gas

to mix with the air at the suction side of the fan and the ignition spark will occur at the main burner.

(5) When the burner ignites, the flame is detected by the control box through the

combined flame sensor/ignitor and the ignition spark is stopped. Both the lockout lamp (red) and the boiler run lamp (green), the upper lamp adjacent to the flame symbol, will be illuminated. The boiler is now in its normal run condition.

(6) The burner will continue to operate until the gas valve interrupts the gas supply.

The gas valve will be closed by the control box if power is interrupted to the boiler by any external control or the boiler thermostat. If an interruption to the gas supply causes loss of the flame the control box with pause for approximately 10 seconds and then attempt to re-ignite the unit. If this attempt fails, ie due to lack of gas supply, the boiler will make two further attempts to ignite at intervals of approximately 1 minute and will then go into a lockout state (red lamp illuminated only). Once gas supply has been resumed the boiler can be reset by turning the boiler off and then on again via the on/off switch on the boiler control panel.

(7) The boiler can also be shut down by any of the flow limit, flow overheat and the

flue overheat thermostats, gas low pressure switch and by the low water pressure switch.

In such an event the green (run) lamp, the upper lamp adjacent to the flame symbol, will be extinguished and only the red (lockout) lamp will be illuminated.

Any failure of the boiler to sequence in the above manner should be investigated using the following trouble shooting flow diagram.

Before attempting any electrical fault finding, always carry out preliminary electrical system checks. On completion of any service/fault finding task which has required the breaking and remaking of electrical connections, the checks, earth continuity, polarity, short circuit, resistance to earth must be repeated.

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Page 31

5.2 FAULT FINDING FLOW CHART

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yes

Continued on sheet 2

yes

STA RT

Is amber switch light on?

Is ther e 23 0V be twe en

terminals L & N?

Is the boiler switched on?

Faulty Switch Neon

-Repl a ce.

Switch On Boiler.

Check External Controls.

Apply Power To Boiler.

Is the boiler thermostat closed?

Is ther e 23 0V be twe en co ntr ol

box pi ns 10 & 2?

Is the air pressure switch stuck

in the NO position?

Is there 230V between pins 6 &

neutral?

Is there con tin uity bet we en pi n

6 & Neutral through motor

resistance?

Is the fan running?

Is motor overload tripped?

Is ther e wi ri ng co nti nu ity

& in-line connector

to motor?

Boiler return is too hot. Allow

to cool. OR faulty thermostat -

Replce.

Check continuity (see section

5.3)

Faulty pipe connections to Air

Press. Switch. OR Faulty Air

Press. Switch - Replace.

Control box faulty.

Motor/Fan faulty - Replace.

Wait for motor to cool.

Identify & correct break.

Page 32

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From sheet 3

yes

Continued on sheet 3

yes

Continued from sheet 1

yes

Does ignition sequence start?

Is lockout light on?

Has the Air Press. Switch

changed over?

Are tubes and connections to the Air Press. Switch sound?

Is the air press. across the Air

Press. Switch more than 4 in

water?

Is the air filter dirty or the air

inlet, exhaust or condensate

pipe blocked?

Is the Burner blocked

Fan faulty - change

Is the gas flow rate to the boiler correct

for the gas type in use (ie LPG or Nat.

Gas)?

Is gas supply pressure at gas

valve correct?

Is gas burner pressure per

specification (Section 4.7)?

Is gas valve openeing?

Check gas supply or turn on

gas cock.

Replace gas orifice.

Faulty gas valve - replace.

Switch off & if problem persists

replace control box.

Blocked air filter - replace

Faulty control box - replace

Correct tube connection

Faulty pressure switc h -

replace

Replace air filter

clear blockage

Clear blockage

Page 33

WD50/2/1997 Chapter 5 : Fault Finding The Keston 50, 60 & 80 Condensing Boilers

Installation & Servicing Instructions

Page : 30

Continued on sheet 2

yes

Continued from She et 2

Is there 230V at valve

Is there 230V at Gas Low

Press. Switch

Faulty Control Box - Replace.

Faulty Ga s Va lve - Repl ace .

Faulty Gas Low Pressure

Switc h - Rep lac e

Is there a spark present?

Is the HT voltage present at

top of ignito electrode?

Is the s par k gap 4 mm ?

Faulty Conrtrol Box - Replace.

Replace/Adjust Spark Plug.

Does the burner ignite?

Electrode Faulty - Replace.

Recheck gas output pressure.

Check HT lead is securely

fixed. Clean or replace burner.

Does flame stop after 5 - 10

seconds?

Is boiler earthed correctly?

Are live and neutral supply

lines crossed at terminals L &

Faulty Control Box - Replace.

Earth Boiler.

Correct Wiring.

Page 34

5.3 CONTINUITY CHECKING

WD50/2/1997 Chapter 5 : Fault Finding The Keston 50, 60 & 80 Condensing Boilers

Installation & Servicing Instructions

Page : 31

STAR T

Is there 2 30 V a t term ina l L?

Is there 23 0V a t the ON /OF F

sw itch (b o th t erm in als )?

Is there 230V at the bo iler

thermostat (both term inals)?

Is there 2 30 V a t the fl ow

overheat thermostat (bo th

term inals)?

Is there 230V at the th ermal

fuse link (both terminals)?

Is there 230V at the flow high

limit the r mo sta t ( bo th

term inals)?

Is there 230V at the w ater

press. switch (both terminals)?

Is there 2 30 V at the flu e

protection thermostat (both

term inals)?

Check external c ontrols.

Faulty switch - Re place.

Thermosta t tripped - reset OR

faulty thermostat - Replace.

High cabinet temperature -

check a ll joints for pro ducts

leakage - Repl ace therma l fuse

High water temperature OR

faulty thermostat - Replace.

Check w ater level header

tank/system pressure OR faulty

switch - Re plac e

Thermosta t tripped - reset OR

faulty thermostat - Replace.

yes

Is there 230V at the gas low

press. switch (both terminals)?

Ch ec k g as su pp ly t o b o iler O R

faulty switch - Replace.

yes

To check continuity connect one probe to a neutral and use the other probe to check for 230V.

Boiler is up to tem perature.

Allow to cool OR pum p not

running OR fa ulty thermostat -

Replace

Page 35

5.4 FUNCTIONAL FLOW WIRING DIAGRAM

WD50/2/1997 Chapter 5 : Fault Finding The Keston 50, 60 & 80 Condensing Boilers

Installation & Servicing Instructions

Page : 32

ON/OFF Switch

Boiler

Flow Overheat

Thermal Fuse

Flow High Limit

Low Water

Flue Overheat

RAM-2EMC22 IGNITION CONTROL

Thermostat

Pressure Switch

610

Lockout (Red)

Run(Green) Indicator

Gas Valve

Gas Low Pressure

ON/OF F Switch

Blower

Air Pressure Switch

EMC Filter

230V 50Hz Fuse 5A

Link

Switch

Indicator

Page 36

5.5 ELECTRICAL WIRING DIAGRAM

WD50/2/1997 Chapter 5 : Fault Finding The Keston 50, 60 & 80 Condensing Boilers

Installation & Servicing Instructions

Page : 33

IGNITION CONTROL

RAM-2EMC22

13 121110

9 8 7 6 5 4 3 2 1

4 3

7 6

FILTER

ON/OFF SWITCH

GREEN LAMP

FLUE OVERHEAT THERMOSTAT

WATER PRESSURE

SWITCH

FLOW HIGH LIMIT

THERMOSTAT

FLOW OVERHEAT

THERMOSTAT

BLOWER

A.P.S.

GAS

SWITCH

GAS

VALVE

5BR 4B

91/OR

10/BK 9G

92/OR

59PK

51/OR

52BK

53W

54G

55BR

90 R

Y/G

12V

11W

93 OR

LEGEND

B -BLUE BK -BLACK OR -ORA NGE R -RED PK -PINK W -WHITE G -GREEN BR -BROWN V -VIOLET Y/G-YELLOW-GREEN

APS-AIR PRESSURE

SWITCH

L -INCOMING

LIVE

N -INCOMING

NEUTRAL

-INCOMING EARTH

12B

6BR

95G

93R

RED LAMP

BOILER

THERMOSTAT

THERMAL FUSE

56R

Page 37

5.6 ILLUSTRATED WIRING DIAGRAM

WD50/2/1997 Chapter 5 : Fault Finding The Keston 50, 60 & 80 Condensing Boilers

Installation & Servicing Instructions

Page : 34

ILLUSTR A TED WIRING DIAGRAM

RAM Control

Overheat Stat

Flow High Limit S tat

Boiler Stat

Air Pressure Switch

Gas Valve

Flue Overheat Stat

Ignition Electrode

Low Water Pressure Switch

Gas Low Pressure Switch

Blower

51OR

52BK

93OR

92OR

11W

55BR

10BK

Y-G

W 5BR 4B

N L

53W

54G

91OR

95G

93R

12V

90OR

ON/OFF

SWITCH

Lockout

Lamp

Run

Lamp

FILTER

1 2 3 4 5 6 7

59PK

90R

Thermal Fuse

56R

Page 38

5.7 Exploded Assembly Diagrams

5.7.1 Boiler Controls Assembly

WD50/2/1997 Chapter 5 : Fault Finding The Keston 50, 60 & 80 Condensing Boilers

Installation & Servicing Instructions

Page : 35

K50 - 05.4.00.00.0 K60 - 06.4.00.00.0 K80 - 08.4.00.00.0

BOILER CONTROLS

111

04.4.00.04.0

SEALING GASKET

SECTION 1

115

04.4.06.00.0

ON/OFF SWITCH

04.1.00.84.0

SCREW

RED LAMP

04.4.08.00.0

117

GREEN LAMP

04.4.07.00.0

116

GAUGE

04.4.09.00.0

118

NEON BULB

04.4.12.00.0

121

SCREW

04.4.00.10.0

TERMINAL BLOCK

04.4.05.00.0

113

04.4.04.00.1-K80

04.4.04.00.0-K50/60

110

SWITCH

AIR PRESSURE

MAUVE

BLUE/WH.

04.4.10.00.2

04.4. 10.00.0-K50/60

119

HARNESS

PACTRO L RAM

109

SUPRESSOR FILTER

MAINS

04.4.02.00.0

SECTION 1

114

BASE LABEL

TERMINAL BLOCK

04.4.00.03.0

SECTION 1

123

04.4.18.00.0

THERMAL FUSE

124

04.4.00.06.0

SCREW

125

04.4.19.00.0

FUSE SOCKET

SECTION 1

ASSEMBLY

04.4.20.00.0

FUSE ISOLATOR

143

04.1.00.40.0

SCREW

154

158

04.4.11.00.0

04.4.11.00.1

120

PACTRO L RAM

04.4.01.00.0

04.4.01.00.1

108

PACTRO L RAM

IGNITION CONTROL

IGNITION C AB LE

PACTRO L

08.4.10.00.0-K80

Page 39

5.7.2 Waterway, Condensate & Flue Assembly

WD50/2/1997 Chapter 5 : Fault Finding The Keston 50, 60 & 80 Condensing Boilers

Installation & Servicing Instructions

Page : 36

K50 - 05.2.00.00.0 K60 - 06.2.00.00.0 K80 - 08.2.00.00.0

THERMOSTAT

WATER FLOW OU T

04.2.21.00.0

WATER WAY, CONDENSATE & FLUE ASSEMBLY

04.1.00.80.1

SCREW

04.2.13.00.1

IGNITER

04.2.00.28.2

IGNITER GA S KET

04.2.28.00.0

PRESS. TEST FITT .

04.2.00.29.1

SCREW

04.2.00.25.0

MANIFOLD

04.2.12.00.1

SIGHT GLASS

04.2.00.43.1

WATER INLET

04.2.00.24.1

GASKET

SEEGER RING

04.2.00.53.0

126

04.2.16.00.0

04.1.00.41.0

SCREW

DRAIN VALVE

04.2.00.54.0

GASKET

122

08.2.11.00.0-K80

06.2.11.00.0-K60

05.2.11.00.0-K50

BURNER

LABEL

04.2.00.58.0

HIGH VOLTAGE

04.2.10.00.0-K50/60

08.2.10.00.0-K80

HEAT EXCHANGER INSULATION

08.2.01.00.1-K80

04.2.01.00.1-K50/60

HEAT EXCH ANGER

04.2.17.00.0

THERMOSTAT

WATER RETURN

TRAP HOSE

CONDENSATE

04.2.00.34.1

04.2.00.57.0

HOSE CLAMP

CONDENSATE HOSE

04.2.00.48.1

CONDENSATE TRAP

04.2.14.00.1

28 BE ND

04.2.00.76.0

156

PIPE

04.2.00.60.0

28 WATER RETURN

04.2.00.65.0-K50/60

28 WATER RETURN

PIPE

08.2.00.65.0-K80

149

04.1.00.78.0

SCREW

04.2.00.32.2

WATER OUT

THERMOSTAT

04.2.22.00.0

FLOW HIGH LIMIT

MANIFOLD

SWITCH

WATER PRESSURE

04.2.23.00.0

04.2.20.00.1

AUTO AIR VEN T

04.2.00.66.0

28 WATER FLOW

PIPE

04.2.00.67.0

28 WATER FLOW

PIPE

04.2.00.61.0

28 ELBOW

04.2.00.33.2

GASKET

04.1.00.79.1

150

SCREW

EXHA UST PI PE

TEST PLUG

COMBUSTION

04.2.00.49.1

THERMOSTAT

FLUE OVERHEAT

04.2.19.00.0

04.1.00.41.3

SCREW

SECTION 3

04.2 .18.00.0-K50/ 60

08.2.18.00.0-K80

Page 40

5.7.3 Air - Gas Assembly

WD50/2/1997 Chapter 5 : Fault Finding The Keston 50, 60 & 80 Condensing Boilers

Installation & Servicing Instructions

Page : 37

K50 - 05.3.00.00.0 K60 - 06.3.00.00.0 K80 - 08.3.00.00.0

AIR-GAS ASSEMBLY

PRESS. TEST FITT.

04.2.28.00.0

SCREW

04.3.00.28.0

104

GAS TEE

04.3.00.34.1

PRESSURE SWITCH

LOW GAS

04.3.09.00.0

04.3.07.00.0

REGULATOR GAS VALVE

RUBBER PLUG

04.3.00.18.0

04.3.00.39.0

AIR ORIF FICE SCREW

GASKET

04.3.00.20.0

04.3.00.19.0

AIR/GAS

MANIFOLD PLUG

05.3.00.17.0-K50NG

GA S O RIF IC E

05.3.00.17.1-K50LPG

06.3.00.17.0-K 60N G

06.3.00.17.1-K60LPG

08.3.00.17.0-K 80N G

08.3.00.17.1-K80LPG

FLEXIBLE TUBE

AIR/GAS

04.3.05. 00.1-K50/K60

103

AIR ADJ. SCREW

04.3.10.00.0

08.3.05.00.1-K80

SCREW

04.1.00.81.0

04.1.00.38.0

SEALING GASKET

GASKET

107

04.2.00.33.0

04.3.03.00.0

CAPACITOR

BLOWER

04.3.01.00.0

04.3.04.00.0

BLOWER

RUBBER ISOLATOR

SECTION 1

AIR HOSE CLAMP

04.3.00.21.0

08.3.00.15.0-K80

04.3.00.15.0-K50/K60

AIR INLET FLEX. CONNECTOR

04.3.08.00.3

GAS INLET

FLEXIBLE TUBE

08.3.00.13.1-K80LPG

08.3.00.13.0-K 80NG

06.3.00.13.1-K60LPG

06.3.00.13.0-K 60NG

05.3.00.13.1-K50LPG

AIR ORIFICE

05.3.00.13.0-K 50NG

GAS IN LE T GASKE T

04.3.00.29.0

NUT

04.3.00.30.0

100

102

04.3.00.32.0

HIGH PRESS. TUBE

LOW PRESS. TUBE

04.3.00.31.0

101

MANIFOLD

AIR/GAS

04.3.06.00.0

04.3.00.16.0

GAS VALVE SCREW

107

105

MAIN SOLE NOID

04.3.07.01.0

144

CONNECTOR BLOCK

04.3.07.02.0

145

151

04.3.07.03.0

SECONDARY SOLENOID

155

04.1.00.82.0

SCREW

152

04.1.00.76.0

SCREW

Page 41

5.7.4 Casing Assembly

WD50/2/1997 Chapter 5 : Fault Finding The Keston 50, 60 & 80 Condensing Boilers

Installation & Servicing Instructions

Page : 38

A U

CASING ASSEMBLY

K50 - 05.1.00.00.0 K60 - 06.1.00.00.0 K80 - 08.1.00.00.0

SCREW

04.1.00.41.0

BURN ER ACCE SS COVER

04.1.00.32.0

28mm GROMMET

04.1.00.49.1

42mm GROMMET

04.1.00.47.0

FLOW LABEL

04.1.00.53.0

04.1.00.52.0

EXH AUST FLUE LA BE L

TOP COVER

04.1.09.00.1

HINDER CLAM P

17.1.00.03.2

SCREW

04.1.00.40.0

AIR INLET LABEL

04.1.00.51.0

NEG. PR. ADAPT.

04.`1.00.62.0

157

04.1.14.00.1

AIR FILTER COVER

AIR FILTER

17.1.12.00.0

04.1.00.61.0

CABLE HOLD ERS

NAME PLATE

05.1.00.50.0-K50

06.1.00.50.0-K60

08.1.00.50.0-K80

CONTROLS PLATE

04.1.19.00.1

04.1.00.43.0

WASHER

EARTHI NG LOCKWASHER

04.1.00.45.0

NUT

04.1.00.42.0

04.1.03.00.0-K50/60

OUTER SHELL

08.1.03.00.0-K80

04.1.00.58.0

TEST POINT LABEL

WIRE RETAI NER

04.1.16.00.0

ELECTRIC MAIN

GAS INLET LAB EL

04.1.00.59.0

04.1.00.75.0

PLASTIC PLUG

04.1.00.39.0

NUT

04.1.00.38.0

WASHER

22mmGROMMET

04.1.00.49.0

08.1.13.00.0-K80

FRONT DOOR

04.1.13.00.0-K50/60

148

04.1.00.77.0

SCREW

04.1.12.00.0

FRONT PANEL

04.1.00.60.0

FLAME LABEL

FOAM GASKET

04.1.00.48.0

WASHER

04.1.00.43.0

04.1.00.42.0

NUT

FIXING RO D

HE AT EXC HANGER

04.1.00.33.0

04.1.00.56.1

ILLUSTRATED WIRING DIAGRAM

05.1.00.57.0-K50

KESTON LABEL

SILENCER

04.1.20.00.1

04.1.00.35.0

BRACKET

04.1.30.00.0

EXHAUST TERMINAL

04.1.18.00.0

GAS VALVE

04.1.00.76.0

SCREW

17.1.09.00.0

SHUTTING CLAMP

WARNING LAB EL

04.1.00.55.0

FRONT DOOR SCREW

04.1.00.37.0

RETURN LABEL

04.1.00.54.0

BLOWER PLATE

04.1.00.36.0

06.1.00.57.0-K60

08.1.00.57.0-K80

Page 42

5.7.5 Exploded Diagrams Parts Reference List

Boiler Controls Assembly (Fig. 5.7.1) GC Number Code Description

E01 074 108 Ignition Control Box 170084 110A Air Pressure Switch (Keston 80) 379 744 110B Air Pressure Switch (Keston 50 & 60) 114 076 113 Electrical Terminal Block 114 077 115 On/Off Switch 114 078 116 Green (Run) Lamp 114 079 117 Red (Lockout) Lamp 114 080 119 Pressure Gauge

Waterway, Condensate & Flue Assembly (Fig. 5.7.2) GC Number Code Description

114 022 43A Heat Exchanger (Keston 50 & 60) 114 023 43B Heat Exchanger (Keston 80) 375 523 46A Burner (Keston 50) 375 524 46B Burner (Keston 60) 375 525 46C Burner (Keston 80) 375 526 47 Burner Head Gasket 114 028 49 Sight Glass 375 527 50 Ignitor Gasket 114 120 51 Spark Ignition Electrode 114 029 54 Pressure Test Nipple 114 032 59 Condensate Trap 114 035 61 Return Drain Valve 375 530 64 Boiler Thermostat 375 532 70 Flue Overheat Thermostat 114 043 73 Combustion Test Plug 114 042 72 Automatic Air Vent 375 533 75 Flow Overheat Thermostat 375 534 78 Flow High Limit Thermostat 114 045 79 Water Pressure Switch

Air - Gas Assembly (Fig. 5.7.3) GC Number Code Description

114 046 80 Combustion Blower 114 051/052/053 87A/B/C Air Orifice (Keston 50/60/80 Nat Gas) 114 089/090/091 87D/E/F Air Orifice (Keston 50/60/80 LPG) 375 536 95 Gas Valve 114 029 54 Pressure Test Nipple 114 073 105 Low Gas Pressure Switch 114 056/057/058 91A/B/C Gas Injector (Keston 50/60/80 Nat Gas) 114 061/062/063 91D/E/F Gas Injector (Keston 50/60/80 LPG)

Casing Assembly (Fig. 5.7.4) GC Number Code Description

375 541 1A Cabinet Outer Shell (Keston 50 & 60) 375 542 1B Cabinet Outer Shell (Keston 80) 114 002 20A/B/C Data Badge (Keston 50/60/80) 375 543 3 Air Filter Cover 114 105 22 Air Filter 375 545 5 Cabinet Top Cover 375 546 6 Burner Access Cover Plate 114 010 30 Illustrated Wiring Diagram 375 548 12A Front Door (Keston 50 & 60) 375 549 12B Front Door (Keston 80)

WD50/2/1997 Chapter 5 : Fault Finding The Keston 50, 60 & 80 Condensing Boilers

Installation & Servicing Instructions

Page : 39

Page 43

6. ROUTINE (ANNUAL) SERVICING

To ensure the continued safe and efficient operation of the boiler it is necessary to carry out routine servicing at regular intervals. The frequency of the servicing will depend upon the particular operating conditions, but it is recommended that an annual service should be carried out by a

competent engineer. The appliance has an integral air filter, mounted at the top right hand side of the boiler, to which

the air intake pipe is connected. This filter should be ex amined every time the boiler is serviced. It may need more frequent inspection ac cording to the condition of the atm osphere in which the air intake terminates.

Note: The air filter can be easily blocked if the boiler is running on or near a building site having

an excess of airborne dust. It is essential, with a premix gas burner, that the air is clean and free of dust.

It is the law that any service work must be carried out by competent qualified persons.

6.1 Pre-Service Checks

It is recommended that an inspection should be carried out prior to shutting down the unit for servicing. Remove the front cover by releasing the 2 slotted screws on the top and lifting the cover from the base (Front cover located by two pegs). The following items should be observed:

a. Smooth starting and running of the blower. b. Smooth lighting of the burner. c. Check for leakage of gas, gas/air or combustion products. d. Check for condensate leaks. e. Check the colour and appearance of the flame. A sky blue flame slightly off the

burner gauze is normal. The burner itself should appear dark. Any glow on the burner indicates gauze blockage requiring cleaning, an incorrect gas flow or an air intake blockage.

f. Check that the temperature differential between the flow and return pipes is less

than 15

C. The temperature difference should be between 10oC and 15oC. g. Check for water soundness. h. Inspect the flue vent and air intake pipework. Joints must be sound and all

pipework well bracketed.

i. Check that there is a steady fall back to the boiler from the flue pipe to allow

condensate to run back into the boiler (See Section 2.8.3 Slope).

j. With the boiler operating at a low return temperature (i.e. less than 50

C) check

that the condensate flows freely from the condensate line.

6.1.1 Burner & Heat Exchanger Blockage Checks

i) Turn off the boiler & shut off the gas supply to the boiler. ii) Remove the pressure point screws from points A & B. Attach a differential

gauge.

iii) Turn on the boiler and wait for the fan to reach full speed. Obviously the

burner will not light.

iv) The pressure difference should be lower than : 8 mbar on the Keston 50,

8.4 mbar on the Keston 60 and 11.2 mbar on the Keston 80. If not, clean the burner.

WD50/2/1997 Chapter 6 : Servicing The Keston 50, 60 & 80 Condensing Boilers

Installation & Servicing Instructions

Page : 40

Page 44

v) Turn off the electrical supply to the boiler. vi) Remove the pressure point screw from point C and transfer the tube from

point A to C, replacing the screw on point A.

vii) Turn on the electrical supply to the boiler (gas still off), wait for the fan to

reach full speed.

viii) The pressure difference should be below 11 mbar. If not, clean heat

exchanger. ix) Disconnect the gauge from point B. Refit the screw. x) Read pressure of point C. xi) The maximum pressure should be 3 mbar. If the pressure is greater than

this, check the flue for blockage. xii) Turn off the electrical supply to the boiler. xiii) Remove the pressure gauge tube and refit the screw. xiv) Open the gas service cock.

6.2 Recommended Routine Service

a. Inspect the air filter located at the top right hand side of the boiler. Release the

projecting leaf on the filter box and slide out the filter. If the filter looks dirty remove the dirt with a vacuum cleaner or by other means. If

in any doubt renew the filter element.

b. Remove the burner head (Section 7.7) and inspect the burner appearance. Black

markings or other discolourations on the gauze indicate too much gas or a lack of air possibly due to a blocked air filter. Any breakages or damage to the burner mesh indicate the burner must be replaced.

WD50/2/1997 Chapter 6 : Servicing The Keston 50, 60 & 80 Condensing Boilers

Installation & Servicing Instructions

Page : 41

Pressure Test Point B

Pressure Test Point A

Burner Heat (From Above)

Pressure Test

Point C

Combustion Test Point

Flue Overheat Thermostat

Heat Exchanger Shell

Flue

Fig 6.1.1 Pressure Test Point Locati ons

Page 45

c. If necessary, either due to discolouration or a high pressure differential between

points A & B in the pre-service checks, clean the burner with a mild

household

detergent and rinse under a hot running tap.

d. If necessary, either from visual inspection or a high pressure differential between

points B & C in the pre-service checks, clean the heat exchanger using a suitable stiff plastic bristle brush, vacuum out any large particles and flush the heat exchanger with fresh water until the water flowing from the condensate drain is clear. When brushing the heat exchanger take care not to damage the condensing plug in the lower half of the heat exchanger.

e. Remove the condensate trap (Section 7.10) and unscrew the cap. Clean by

flushing through with clean running water. Reassemble in reverse order.

f. Check the electrodes mounted on the burner head. If the points are damaged or

burnt replace them. Check that the spark gap measures 4 mm.

g. Replace the burner head, renewing any gasket as necessary, and reconnect the

gas/air supply and the ignition lead. Ensure the flanged gas/air supply joint is air tight.

h. Turn on the electrical supply to the boiler and allow the boiler to reach operating

temperature levels.

i. Check for gas leakage around the burner head, air/gas flexible hose to the burner

head and ignitor plug if they have been removed.

j. Visually inspect the burner through the glass spy hole at the burner head (a small

mirror will prove useful).

k. Recheck the burner pressure by following the procedure detailed in Section 4.7

WD50/2/1997 Chapter 6 : Servicing The Keston 50, 60 & 80 Condensing Boilers

Installation & Servicing Instructions

Page : 42

Page 46

7. REPLACEMENT OF PARTS

INDEX

7.0 GENERAL

7.1 PRECAUTIONS

7.2 ACCESS

7.3 PROCEDURES - GENERAL

7.4 ELECTRICAL

7.4.1 ON/OFF SWITCH

7.4.2 BOILER THERMOSTAT

7.4.3 NEONS

7.4.4 FLOW OVERHEAT, FLOW HIGH LIMIT & FLUE PROTECTION

THERMOMSTATS

7.4.5 WATER PRESSURE SWITCH

7.4.6 IGNITION CONTROL BOX

7.4.7 AIR PRESSURE SWITCH

7.4.8 COMBUSTION BLOWER

7.4.9 GAS CONTROL VALVE

7.4.10 GAS LOW PRESSURE SWITCH

7.5 GAS ORIFICE

7.6 SPARK IGNITION/FLAME DETECTION ELECTRODE

7.7 BURNER HEAD & BURNER

7.8 HEAT EXCHANGER

7.9 AIR FILTER

7.10 CONDENSATE TRAP

7.11 PRESSURE GAUGE

7.12 SIGHT GLASS

7.13 HT IGNITION LEAD

7.14 AIR VENT

7.15 AIR ORIFICE

WD50/2/1997 Chapter 7 : Replacement Of Parts The Keston 50, 60 & 80 Condensing Boilers

Installation & Servicing Instructions

Page : 43

Page 47

7.0 GENERAL

The following must always be carried out by a competent/qualified person.

7.1 PRECAUTIONS

i) Always switch off the mains electricity supply and disconnect the plug at the

isolating switch and socket. (If a switch only is used then remove the fuse.)

ii) Gain access to the appliance (Section 7.2) and turn off the gas supply at the

appliance service cock.

7.2 ACCESS

i) Remove the front door by releasing the two slotted screws to the front of the top

panel. The front panel may then be removed by tilting forward and lifting vertically to disengage the two locating studs in the base of the front panel.

ii) Access to the burner head can be gained by removing the access plate in the top

panel of the appliance.

7.3 REPLACEMENT PROCEDURES

i) Always replace in the reverse order unless otherwise stated. ii) Electrical connections must be remade in accordance with the Wiring Diagram

(Section 5.5).

iii) Test the soundness of any gas carrying or water carrying joint broken during the

service procedures.

7.4 ELECTRICAL COMPONENTS

7.4.1 On/Off Switch (Fig. 5.7.1 item 115)

i) Isolate the appliance (Section 7.1) ii) Gain access (Section 7.2) iii) Remove the push on connectors from the switch taking note of the

correct positions.

iv) Press in the catches and push the switch forwards through the control

panel. v) Reassemble (Section 7.3) vi) Check for correct operation of the switch.

7.4.2 Boiler Thermostat (Fig. 5.7.2 item 64) i) Isolate the appliance (Section 7.1)

ii) Gain access (Section 7.2) iii) Remove the push on connectors from the thermostat taking note of the

correct positions. iv) Unscrew the two retaining screws and remove the thermostat. v) Reassemble (Section 7.3)

NB: When fitting the new thermostat it is a requirement to smear a

thin film of heat sink compound between the thermostat and plate. This, combined with fitting the new thermostat tightly to the plate, ensures a good contact.

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7.4.3 Neons (Fig. 5.7.1 items 116 & 117) i) Isolate the appliance (Section 7.1)

ii) Gain access (Section 7.2) iii) Remove the push on connectors from the neon taking note of the correct

positions.

iv) Press in the catches and push the neon forward through the control

panel.

v) Pull the centre core of the neon from its housing to expose the bayonet

fitting bulb. vi) Reassemble (Section 7.3) vii) Check for correct operation of the neons.

7.4.4 Flow Overheat (Fig. 5.7.2 item 75) , Flow High Limit (Fig. 5.7.2 item 78) & Flue Protection Thermostats (Fig. 5.7.2 item 70)

i) Isolate the appliance (Section 7.1) ii) Gain access (Section 7.2) iii) Remove the push on connectors from the thermostat taking note of the

correct positions. iv) Unscrew the two retaining screws and remove the thermostat. v) Flue protection thermostat only

The thermostat seal is maintained via a small 'O' ring between thermostat

and flue pipe. If this is damaged on removal it must be replaced. vi) Reassemble (Section 7.3)

NB: When fitting the new thermostat it is a requirement to smear a

thin film of heat sink compound between the thermostat and plate. This, combined with fitting the new thermostat tightly to the plate, ensures a good contact.

7.4.5 Water Pressure Switch (Fig. 5.7.2 item 79) i) Isolate the appliance (Section 7.1)

ii) Shut off the water supply to the appliance. iii) Gain access (Section 7.2) iv) Drain the system to below the level of the appliance using the drain off

tap at the base of the heat exchanger.

v) Remove the push on connectors from the water pressure switch taking

note of the correct positions. vi) Unscrew the pressure switch. vii) Reassemble (Section 7.3).

NB: Use a little jointing compound or PTFE tape on the thread. viii) Refill the system (See Section 4 - Commissioning).

7.4.6 Ignition Control Box (Fig. 5.7.1 item 108) i) Isolate the appliance (Section 7.1)

ii) Gain access (Section 7.2) iii) Remove the HT ignition lead. iv) Pull off the multi-pin connector away from the box. v) Unscrew the two screws securing the control box to the casing and

remove the box.

vi) Reassemble (Section 7.3)

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7.4.7 Air Pressure Switch (Fig. 5.7.1 item 110) i) Isolate the appliance (Section 7.1)

ii) Gain access (Section 7.2) iii) Remove the push on connectors from the air pressure switch taking note

of the correct positions.

iv) Disconnect the union to one plastic tube connection and pull off the

second plastic tube from the air pressure switch.

v) Unscrew the two screws mounting the air pressure switch body to the

boiler casing.

vi) Reassemble (Section 7.3)

NB: Ensure the yellow/green earth connection tag is securely fixed

behind the lower mounting screw.

7.4.8 Combustion Blower (Fig. 5.7.3 item 80) i) Isolate the appliance (Section 7.1)

ii) Gain access (Section 7.2) iii) Remove the cover plate to the electrical connections on the blower motor

by removing the four retaining screws.

iv) Disconnect the wires to the combustion blower taking note of the correct

positions.

v) Remove the allen screws fixing the air intake pipe flange and the gas/air

mixture pipe flange to the blower.

vi) Undo the two nuts securing the combustion blower base plate to the

cabinet base and lift out the combustion blower.

vii) Unscrew the three bolts fixing the base plate and anti-vibration mounts to

the combustion blower.

viii) Reassemble (Section 7.3)

NB: When reassembling inspect any gaskets for damage and replace

if necessary.

ix) Reset the gas rate (See Section 4 - Commissioning)

7.4.9 Gas Control Valve (Fig. 5.7.3 item 95) i) Isolate the appliance (Section 7.1)

ii) Gain access (Section 7.2) iii) Remove the cover concealing the electrical connections on the front of

the gas valve.

iv) Remove the push on connectors exposed taking note of the correct

positions.

v) Remove the push on connectors to the gas low pressure switch taking

note of the correct positions. vi) Remove the earth connection to the side of the gas valve. vii) Remove the four allen bolts securing the gas inlet flanged connections to

the gas control valve. viii) Undo the four bolts fixing the base of the gas control valve to the gas

outlet block. ix) Remove the gas valve. x) Unscrew the gas low pressure switch at its connection to the gas control

valve body. xi) Reassemble (Section 7.3) xii) Reset the gas rate (See Section 4 - Commissioning)

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7.4.10 Gas Low Pressure Switch (Fig. 5.7.3 item 105) i) Isolate the appliance (Section 7.1)

ii) Gain access (Section 7.2) iii) Remove the push on connectors to the gas low pressure switch taking

note of the correct positions. iv) Unscrew the gas low pressure switch from the brass holder. v) Reassemble (Section 7.3)

7.5 GAS ORIFICE (Fig 5.7.3 item 91) i) Isolate the appliance (Section 7.1)

ii) Gain access (Section 7.2) iii) Unscrew and remove the brass plug from the gas outlet block. iv) Remove the rubber seal from the injector housing. v) Insert a flat blade screwdriver into the exposed hole and unscrew the gas injector. vi) Check the injector is the correct size for the boiler size and fuel type. vii) Reassemble (Section 7.3)

NB : When fitting the new gas injector ensure that the injector is screwed fully home past the gas port into the chamber from the gas valve.

viii) Reset the gas pressure (See Section 4 - Commissioning)

7.6 SPARK IGNITION/FLAME DETECTION ELECTRODE (Fig. 5.7.2 item 51) i) Isolate the appliance (Section 7.1)

ii) Gain access (Section 7.2) iii) Remove the pull off HT lead to the spark ignition electrode. iv) Remove the burner head (Section 7.7 steps iv) to vii). v) Undo the screws to the spark ignition electrode flange located on the burner

head and withdraw the spark ignition electrode.

vi) Reassemble (Section 7.3)

NB: When reassembling inspect the gasket for damage and replace if

necessary. With the new spark ignition electrode in place it is essential to ensure the gap between the tip of the electrode and the burner surface is 4 mm. Distance above or below 4 mm will affect the ignition performance. If necessary gently bend the electrode taking care not to damage the ceramic insulator.

7.7 BURNER HEAD & BURNER (Fig. 5.7.2 items 46 & 48) i) Isolate the appliance (Section 7.1)

ii) Gain access (Section 7.2) iii) Remove the pull off HT lead to the spark ignition/flame detection electrode head. iv) Remove the four screws retaining the access panel (Fig. 5.7.4 item 6) and

remove the access panel from the top of the cabinet.

v) Remove the two allen screws fixing the flange gas/air mixture pipe connection to

the burner head.

vi) Remove the four allen screws fixing the burner head to the top of the heat

exchanger.

vii) Withdraw the burner & burner head from the top of the heat exchanger through

the access panel opening in the top of the cabinet.

viii) Unscrew the burner from the burner head taking care not to damage the burner

mesh.

ix) Reassemble (Section 7.3)

NB: When reassembling inspect any gaskets for damage and replace if

necessary. Set the spark gas as detailed in Section 7.6.

x) Reset the gas rate (see Section 4 - Commissioning)

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7.8 HEAT EXCHANGER (Fig. 5.7.2 item 43) i) Isolate the appliance (Section 7.1)

ii) Gain access (Section 7.2) iii) Shut of the water supply to the appliance. iv) Remove the burner head (Section 7.7) v) Drain the system to below the level of the appliance using the drain off tap at the

base of the heat exchanger. vi) Remove the boiler thermostat (Section 7.4.2) vii) Remove the push on connectors to the water pressure switch, flow overheat

thermostat, flow high limit thermostat and flue protection thermostat taking note of

the correct positions. viii) Remove the condensate trap (Section 7.10) ix) Remove the pressure gauge phial located next to the drain off tap. x) Disconnect the flow and return compression couplings to the flow and return

pipes exiting the top of the boiler. xi) Remove the push on flue connection to the flue pipe exiting the top of the boiler. xii) Remove the complete air filter assembly and flexible air pipe. xiii) Remove the nut fixing the strap retaining the base of the heat exchanger and pull

out the strap by unhooking it from its fixing behind the heat exchanger. xiv) Remove the allen screw securing the top of the heat exchanger to its mounting

bracket. xv) Remove the five screws fixing the top of the cabinet. xvi) Remove the heat exchanger, with pipework attached, & the top of the cabinet. xvii) Separate the top of the cabinet from the combined assembly. xviii) Remove the flow and flue pipework from the heat exchanger (Replacement heat

exchangers are supplied with return pipework attached). xix) Reassemble (Section 7.3) xx) Recommission (Section 4 - Commissioning)

7.9 AIR FILTER (Fig. 5.7.4 item 22) i) Isolate the appliance (Section 7.1)

ii) Gain access (Section 7.2) iii) Drop the lower section of the air filter housing by pulling forward the securing flap. iv) Open the lower section as far as possible and pull out the combined paper filter

element with rubber seal.

v) Reassemble (Section 7.3)

NB: When fitting the new air filter take care to ensure that the new filter is placed to cover completely the air intake entry into the boiler cabinet.

7.10 CONDENSATE TRAP (Fig. 5.7.2 item 59) i) Isolate the appliance (Section 7.1)

ii) Gain access (Section 7.2) iii) Disconnect the condensate line from the base of the heat exchanger. iv) Disconnect the condensate line from the base of the flue assembly. v) Disconnect the condense lines from the projection of the condensate trap from

the base of the cabinet. vi) Withdraw the condensate trap. vii) Mop up any spilled condensate. viii) Reassemble (Section 7.3)

NB: When re-fitting condensate trap pour water into the condensate hose

from the base of the heat exchanger until nearly full. Then reconnect the condensate hose to the base of the heat exchanger.

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7.11 PRESSURE GAUGE (Fig. 5.7.1 item 119) i) Isolate the appliance (Section 7.1) and shut off the boiler from the water circuit.

ii) Gain access (Section 7.2) iii) Shut off the pressure measurement point at the return drain valve located at the

base of the heat exchanger.

iv) Remove the phial from its mounting at the return pipe entry to the base of the heat

exchanger.

v) Press in the catches and push the pressure gauge forward through the control

panel. vi) Reassemble (Section 7.3) vii) Refill the system (See Section 4 - Commissioning)

7.12 SIGHT GLASS (Fig. 5.7.2 item 49) i) Isolate the appliance (Section 7.1)

ii) Gain access (Section 7.2) iii) Unscrew the sight glass fitting from the burner head. iv) Reassemble (Section 7.3)

7.13 HT IGNITION LEAD (Fig 5.7.1 item 120) i) Isolate the appliance (Section 7.1)

ii) Gain access (Section 7.2) iii) Remove the lead from the electrode and the ignition control box. iv) Reassemble (Section 7.3)

7.14 AIR VENT (Fig. 5.7.2 item 72) i) Isolate the appliance (Section 7.1)

ii) Gain access (Section 7.2) iii) Shut off the water supply to the appliance. iv) Gain access (Section 7.2) v) Drain the system to below the level of the appliance using the drain off tap at the

base of the heat exchanger. vi) Unscrew the air vent. vii) Reassemble (Section 7.3) viii) Refill the system (See Section 4 - Commissioning)

7.15 Air Orifice (Fig. 5.7.3 item 87) i) Isolate the appliance (Section 7.1)

ii) Gain access (Section 7.2) iii) Disconnect the flexible air intake hose from the air inlet manifold (Fig 5.7.3 item

102) iv) Unscrew the air orifice grub screw (Fig 5.7.3 item 83) to release the air orifice. v) Lift the air orifice from its seat in the air inlet manifold. vi) Reassemble (Section 7.3) NB: When replacing the air orifice ensure that the new orifice is seated with the

chamfer facing upwards.

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8. SHORT SPARE PARTS LIST

Item GC No Part Denomination Item GC No Part Denomination

22 114 105Air Filter 46 375 523Burner

375 524 375 525

47 375 526Burner Manifold Gasket 50 375 527Ignitor Gasket

51 114 120Ignitor/Sensor Probe 56 114 030Flexible Hose Gasket

64 375 530Boiler Thermostat 70 375 532Flue Thermostat

75 375 533Flow Overheat Thermostat 78 375 534Flow High Limit Stat

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Item GC No Part Denomination Item GC No Part Denomination

94 375 535Gas Valve Outlet Gasket 107 375 529Flexible Hose Gasket 95 375 536Gas Valve 99 375 537Gas Inlet Gasket

108 E01 074 Ignition Control Box 110 170 084Air Pressure Switch

379 744

120 E01 075 HT Ignition Cable

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SHORT SPARE PARTS LIST FOR THE KESTON

CONDENSING BOILER RANGE

Item GC No Part Denomination

22 114 105 Air Filter 46 375 523 Burner (Keston 50)

375 524 Burner (Keston 60)

375 525 Burner (Keston 80) 47 375 526 Burner Manifold Gasket 50 375 527 Ignitor Gasket 51 114 120 Ignitor/Sensor Probe 56 114 030 Flexible Hose Gasket 64 375 530 Boiler Thermostat 70 375 532 Flue Thermostat 75 375 533 Flow Overheat Thermostat 78 375 534 Flow High Limit Thermostat 94 375 535 Gas Valve Outlet Gasket 95 375 536 Gas Multifunctional Control Valve 99 375 537 Gas Valve Inlet Gasket 107 375 529 Flexible Hose Gasket 108 E01 074 Ignition Control Box 110 170 084 Air Pressure Switch (Keston 80)

379 744 Air Pressure Switch (Keston 50 & 60) 120 E01 075 HT Ignition Cable

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†

Read Installation Manual Carefully

†

For open systems ensure that there is at least 8 feet head of water pressure at the top of the boiler.

†

DO NOT remove the dust caps from the air and exhaust pipes until ready to connect.

†

Ensure that ALL dust particles, filings , plastic chips etc. are removed from the inlet pipe.

†

If the installation is a replacement the system must be flushed clean. System should be drained hot, then refilled, then drained

again until the water is clean.

†

Ensure that there is a proper electrical supply ie 230V fused at 5A.

†

Take great care with pipe connections to ensure that no damage is done to the internal pipework.

†

Ensure that the 22mm condensate pipe is not exposed to freezing conditions.

†

Make sure that the exhaust pipe terminates away from windows or vents and is out of reach.

†

Make sure that the air inlet and exhaust pipe outlets are at least 350mm apart.

†

Check tightness of all connections in the boiler before firing.

†

Ensure that the terminals supplied are fitted to both the exhaust and air inlet pipes.

†

Ensure that the air inlet terminal is facing upwards to prevent entry of rain.

†

The system must be free from air before firing.

†

The pump must always run when the boiler is firing.

†

Gravity circuits are not allowed.

†

If TRV's are installed on radiators ensure that a bypass is installed to maintain required flow.

WD 92/0/1997

KESTON CONDENSING BOILERS

IMPORTANT

KESTON 50, 60 & 80

INSTALLATION KEY POINTS

Keston 50 - GC, 80 - GC, 60 - GC, 50, 80 Installation And Servicing Instructions

Specifications and Main Features

Frequently Asked Questions

User Manual