As part of the industry wide “Benchmark” Initiative all Kes ton 130 boilers now include a Benchmark
Installation, Commiss ioning and Service Rec ord Log Book . Pleas e read this c aref ully and complete all
sections relevant to the appliance installation. T he details of the Log Book will be required in the event
of and warranty work being required. There is also a section to be completed after each regular
service visit. The completed Log Book should be left with the customer.
CORGI CONTACT INFORMATION
The boiler should be installed and serviced only by CORGI registered operatives. All CORGI
registered Installers carry a CORGI ID cad, and have a registration number. Both should berecorded in the Benchmark Log Book. You can call CORGI direct on 01256 372300.
Page : ii
Page 4
WD52/0/1997 Chapter 1 : General Instruction The Keston 130 Condensing Boiler
1. GENERAL INSTRUCTION
1.1DESCRIPTION
The Keston Condensing Boiler is unique in its concept and design. 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 15 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 temper ature of the air gas mixtur e is around 1800
combustion at an amazing 1000
o
C thereby reducing the NOx emissions.
The flue system is room sealed and fan powered. The ignition is direct spark and fully
automatic. The boiler housing is not waterproof and should be installed in a position
where it will always be dry. Consideration should also be given to the noise levels
generated by the combustion fan when in operation. A small air intake point is
incorporated within the appliance cabinet to ensure that the interior of the cabinet 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.
o
C but the Keston achieves
The boiler is suitable for c onnection to open vented or, preferably, sealed systems. The
system must be pumped centra l heating or pum ped c entr al heating with combined indirec t
sanitary hot water. Gravity circuits must not be used.
Forming part of the boiler is the heat exchanger which is made f rom a highly corrosion
resistant stainless steel, form ed into tightly wound coil. The hot combustion gases from
the central down firing burner pass thr ough this coil im parting heat into the system 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 f aster when there is a call for heat. This
feature requires a higher water pum ping rate through the boiler otherwise localised boiling
will occur within the boiler. Allow a pressure drop through the boiler of 9.8 ft head (30
kPa) and a water flow of 11 gallons (50 litres) per minute.
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 sanitar y hot water, if the system is
not hot water priority design. If there are special conditions such as excess ive sanitary hot
water usage consult the manufacturer.
1.2BOILER SCHEMATIC
Air is drawn into the boiler through a 50mm muPVC pipe. The air flow is proved by a
differential pressur e across the air control orif ice. Gas is mix ed with combustion air at the
inlet to the fan. The gas flow is r egulated by an orifice located in the housing downstr eam
of the gas valve.
The gas and air are thoroughly mixed in the blower and f ed into the burner located at the
top end of the heat exchanger module. The gas and air mixture is ignited by a direct spark
ignition control system and burns with a blue flame j ust off the surface of the burner. As
the hot products of combustion pass downwards, they are cooled by exchanging heat with
the circulating water which enters the heat exchanger coil at the bottom of the heat
exchanger
.
Installation & Servicing InstructionsPage : 1
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WD52/0/1997 Chapter 1 : General Instruction The Keston 130 Condensing Boiler
Fig. 1.2 - Boiler Schematic
When the return water temperature is below 54
condense inside the heat exchanger, thus inc reasing the boiler efficienc y by releasing the
latent heat of condensation. This condensate falls to the bottom of the heat exchanger
where it is separated from the flue gases and exits f rom the boiler through the condensate
drain. Any condensate formed in the flue runs back down the flueway and is drained at the
base of the flue connection to the heat exchanger or drain points within the flue.
The condensate is very slightly acidic (about the same acidity as vinegar) and should be
piped in a plastic pipe. It is not harmful to the waste disposal system and may be disposed
of as normal waste water.
The flue gases are piped in a 50m m m uPVC pipe to the outside. The temper ature of the
flue gases are usually around 5
pipe should be terminated outside the building from where they cannot re-enter the
building or any other adjacent building.
The heating level may be controlled by room therm ostats, hot water cylinder therm ostats,
programmer time clocks and energy management systems.
1.3RELATED DOCUMENTS
The Keston Condensing Boiler must be ins talled in accordance with the current issue of
the Gas Safety (Installation and Use) Regulations1996, current IEE Wiring Regulations,
Building Regulations, Building Standards (Scotland) Consolidation, and the Bye Laws of
the local Water Undertaking.
o
C, part of the water vapour in the combustion products will
o
C above the temperature of the return water. The flue
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 5482.1:Domestic Propane & Butane Burning Installations
Installation & Servicing InstructionsPage : 2
Page 6
WD52/0/1997 Chapter 1 : General Instruction The Keston 130 Condensing Boiler
BS 5546:Installation Domestic Hot Water
BS 5440.1:Flues
BS 5440.2:Air Supply
BS 7074.1:Expansion Vessels
BS 7593:Treatment of Water in Hot Water Central Heating
Systems
For Timber Framed Buildings, British Gas Publications DM2. Also British Gas
Publications 'Guidance Notes For The Installation Of Domestic G as Condensing
Boilers' and 'Specification For Domestic Wet Central Heating Systems'.
1.4PERFORMANCE DATA
Boiler InputkW42.0
Btu/h143,300
Boiler Output To WaterkW37.7
o
C Flow 60oC Return)Btu/h128,600
(80
Boiler Output To WaterkW39.5
o
C Flow 40oC Return)Btu/h134,800
(60
Boiler Output To WaterkW40.5
o
C Flow 30oC Return)Btu/h138,200
(50
Burner Setting Pressure Factory Preset
)
to 4.0 mbar
3
/hr138.78
(Hot)
Gas Comsumption Afterl/s1.09
10 mins Ft
(CV of Gas - 38.7 MJ/m
(1038 Btu/Ft
3
)
3
1.5GENERAL DATA
Main BurnerKeston Premix
Max. Operating Flow Temp.
o
C80.00
Max. Head (Open Systems)m30.50
Ft100.0
Max. Press. (Sealed Sys.)Bar2.70
Min. Head (Open Systems)m3.0
Ft9.0
Inlet Gas Pressurembar20.0
in wg8.0
Gas Orifice Sizemm3.8
o
Recommended Temperature
C10 to 15
Differential
Flow Connection35mm Copper
Gas ControlWhite Rogers 36E Series
Combustion FanKeston
Return Connection 35mm Copper
Power Supply230V 50Hz
Type LPB 103 220/240
0.6 kW 2900 RPM
Direct SparkRAM 2EMC22
Pwr Consumption610 W
Ext Fuse Rating10 Amp
IgnitionFull Sequence Control
Weight - Full68 kg (150 lbs)
Air Press. SwitchTridelta FS6717-1428
FilterKeston Filter
Weight - Empty61 kg (134 lbs)
Data Badge PosnRight Hand Panel Inside
Case
Gas Supply0.75 inch BSPT Male
Connection(22mm to gas cock)
Water Content7.0 litres
Installation & Servicing InstructionsPage : 3
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WD52/0/1997Chapter 2 - Boiler Connections The Keston 130 Condensing Boiler
2. BOILER LOCATION
All dimensions in mm.
2.1DIMENSIONS AND MINIMUM
CLEARANCES
The boiler must be installed in m inim um
clearances shown to allow subsequent
servicing, and safe operation.
2.2SERVICE CONNECTIONS
254
Gas, water, air and flue pipe,
condensation, and electrical
connections are as shown. Gas : 0.75
inch BSP male. Flow/Return 35 mm
copper.
2.3POSITION
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.
Figure 2.1.2
Dimensions
Air I ntake
Return
50
Flow
Flue
1
1
305
Figur e 2.1.1
127
Minimum Clearances
All dimensions in mm.
890
Condense
Gas
Where a room-sealed
appliance is installed in a
room containg a bath or
shower, any electrical switch or appliance control, utilising mains alectricity, 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 property.
The Keston can be located virtually anywhere desired provided that all regulations are
complied with. Because of the boiler's compact size and venting flexibility, the installation
is not limited to a boiler room setting. Before locating the boiler near a living space
consider whether the sounds generated by the boiler will be objectionable. The boiler may
be located within a cupboard enclosure to reduce noise levels if located within a living
space.
2.4ELECTRICAL
2.4.1Electrical Connections
The boiler must be connected to a permanent 230V ~ 50Hz supply, fused at 10A.
An additional switched live supply 230V ~ 50Hz rated at 2A must be
provided from the external system controls. All external controls and
wiring must be suitable for mains voltage. A pump connection point is
provided within the boiler to enable the optional pump over-run facility to be
used. Alternatively, the appliance can be fed by a single switched 10A supply by
linking the switched and permanent live connection points (see Section 3.8). If a
[NB: Refer to
Section 2.8.3]
Chimneys not used for
venting any other
appliance may be used.
Secure air & flue pipes at
chimney outlet.
Figure 2.3
Installation & Servicing InstructionsPage : 5
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WD52/0/1997Chapter 2 - Boiler Connections The Keston 130 Condensing Boiler
single 10A switched supply is used then the pump over-run facility will not be
enabled.
Wiring external to the boiler must be in accordance with current I.E.E wiring
regulations and local regulations.
The method of connection to the mains electricity supply must facilitate complete
electrical isolation of the boiler, preferably by the use of a fused, unswitched three
pin plug and a shuttered socket-outlet, both complying with the requirements of
BS 1363. There must be only one common method of isolation for the boiler and
its control system.
The appliance must be connected to the 10A 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.
2.4.2External Wiring & Controls
1.The boiler is designed so that all control wiring is external to the boiler.
2.System designs which allow the boiler to fire when there is no pumped
circulation must NOT be used. Provision is made in the boiler for boiler
pump connection with pump over-run facility.
3.A programmer may be used with zone valves to give independent control
of central heating and hot water.
2.5BOILER 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.
2.6GAS SUPPLY
A gas meter should be connected to the service pipe by the local gas region or their
contractor. An existing meter should be checked preferably by the gas region to ensure
that the meter is adequate to deal with the rate of gas supply required. Installation pipes
should be fitted in accordance with BS 6891.
Minimum/Maximum Natural Gas Pressure:
Natural gas pressure before the gas valve must be maintained at 20 mbar (8 in WG) 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.
Supply pipes to the boiler must not be sized less than the boiler inlet connection
(22 mm). Due consideration must be given to the supply pressure to other gas
appliances in the premises. Reduction in dynamic gas supply pressure will result in
intermittent ignition failures. Ensure gas supply pipe work is adequately sized for
the length of run from the meter to the boiler.
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.
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 : Treatment of Water in Hot Water
Central Heating Systems.
Pump isolating valves must be positioned as close to the pump as possible.
aThe Keston 130 is suitable for use on open, vented water systems with combined
feed and vent.
bIt 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.
cAny system must be thoroughly flushed clean of grease, dirt and debris, prior to
connection with the boiler. A trap should be installed in the flow line to collect any
solder, or other debris, from the installation.
dAll water systems must be constructed to comply with requirements of the Local
Water Authority.
eOnly fully pumped systems can be used - gravity systems are strictly
fAlways use a system complying with the requirements of BS 5449 and BS 6798.
gThe system must be so arranged that there shall always be a minimum flow of 11
gpm (50 litres/min) when the boiler is firing. This can be via a specially installed
by-pass arrangement.
hCopper tubing to BS 2871 Part 1 is recommended.
iJointing should be either with capillary, threaded or compression fittings. Pipes
should have a gradient to ensure air is passed easily to vent points and water
flows readily to drain points.
jDraining 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 22 mm in
nominal size and be in accordance with BS 2879.
AIR VENT POINTS
hThese must be fitted at all high points where air will naturally collect and must be
sited to allow complete draining of the system.
not suitable.
2.7.1Open 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 9 ft at the top of the boiler. 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
entrainment 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.
Installation & Servicing InstructionsPage : 7
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WD52/0/1997Chapter 2 - Boiler Connections The Keston 130 Condensing Boiler
Boiler
Expansion
Pipe
28mm
Minimum
Keston
Strainer
Rad. 2Rad. 1
Expansion
Tank
Pump
Minimum
9ft Height
By-pass
Bal.
Valve
Valve
Cylinder
L/S
Valve
Valve
2.7.2Sealed 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
o
C.
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
Care should be taken in making all connections that the risk of leakage is
minimised.
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 locksheild valve on the cylinder return to enable
balancing of the flow rate through the cylinder.
2.7.4Boiler 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 an
automatic by-pass valve to permit balancing of the by-pass flow rate. The
flow/return differential should be 10
maintain this condition with all thermostatic radiator valves closed.
o
C to 15oC. The valve should be adjusted to
Installation & Servicing InstructionsPage : 9
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WD52/0/1997Chapter 2 - Boiler Connections The Keston 130 Condensing Boiler
2.7.5Air 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.
2.7.6Strainers
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.
The boiler guarantee
does not cover heat
exchanger failure due to
debris abrasion within the
system.
Y-Strainer will
collect an y loose
debris in the piping.
Figure 2.7.6 Strainers
2.7.7Pump 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
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.
The Keston 130
condensing boiler offers a
hydraulic resistance of
3.0m (9.8ft) water at the
required flow rate of 50 l/m
(11 gpm).
in order to avoid
Static Pressure - m WC
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
2030405060
10
70
If a single pump is to be used
for the entire installation the
boiler resistance must be added to the pressure loss caused by the rest of the
system and a pump selected that is 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. 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.
2.8FLUE SYSTEM
2.8.1Design
Individual air supply and flue outlet pipes are used. The material used for flue
outlet &/or air inlet must be muPVC to BS 5255 an of an internal diameter of 51
mm. (ie nominal 50mm diameter muPVC solvent weld waste pipe)
O56
40
87
80
Flue Outlet Terminal
Both flue outlet terminal and air inlet terminal are supplied and are illustrated in
Figure 2.8.1 above.
2.8.2Maximum 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:15.0 m
Maximum Flue Outlet Length:15.0 m
However, each bend used has an equivalent length that must be deducted from
the maximum straight length stated above. Knuckle bends must not be used.
Fi
ure 2.8.1 : Terminals
211
O83
O56
Air Intake Terminal
o
A 92.5
sweep elbow is equivalent to 1.0m straight length.
Example:
Air inlet uses two one 92.5o sweep elbows. Hence, maximum length permissible
sweep elbow. Hence, maximum length permissible (ie
c+d in figure 7 = 15.0m - 1.0 m = 14.0m
Installation & Servicing InstructionsPage : 11
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WD52/0/1997Chapter 2 - Boiler Connections The Keston 130 Condensing Boiler
2.8.3Slope
'Horizontal' flue outlet pipework MUST slope at least 5 degrees (80 mm per metre
FLUE
d
c
AIR
b
a
Keston
Figure 2.8.2 : Flue & Air Maximum Length Example
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.
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
Figure 2.8.3 :
Flue Condensate Drain
Point Example
drains must be run to
discharge as detailed in
To Terminal
section 2.11. Such drain points
can be formed using standard
muPVC fittings. Refer to the
example in Figure 2.8.3.
To Boiler
50mm Tee Fitting
2.8.4Terminations
Air inlet terminals must be
facing upwards and positioned
6 in min.
to ensure only fresh air is
drawn into the boiler. The air
terminal must be located
outside of the building.
Drawing of combustion air directly from a ventilated boiler room invalidates the
heat exchanger warranty.
50300A Below openable window, air brick, etc.
7575B Below gutters, soil pipes, drain pipes.
50300C Below eaves.
50200D Below balconies or car port roof.
5075E From vertical drain or soil pipes.
50600F From internal or external corner.
100300G Above ground or balcony or roof.
100600H From surface facing a terminal
1,2001,200IFrom terminal facing a terminal.
1001,200J From opening in a car port.
1,5001,500K Vertically from terminal on same wall.
300300L Horizontally from terminal on same wall.
Table 2.8.4 Minimum Flue Terminations & Air Inlet Dimensions
The air inlet terminal must face upwards to prevent entry of rain into the air intake
pipework.
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.
o
It is advisable for horizontal flue terminals to place a 45
elbow at the end of the
flue to direct the condensate plume up and away from the property.
2.8.5Clearances From Wall
Flue outlet and air inlet terminations must be at least 60 mm and 95 mm
respectively from the wall face.
2.8.6Distance Between Flue Outlet & Air Inlet
There is no maximum - the terminations can be on opposite sides of the dwelling
if desired.
A minimum clearance of at least 500 mm must be left between the terminations.
2.8.7General Installations
All parts of the system must be constructed in accordance with BS 5440 Part 1,
except where specifically mentioned in these instructions.
All pipe work must be adequately supported.
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WD52/0/1997Chapter 2 - Boiler Connections The Keston 130 Condensing Boiler
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.
2.9AIR SUPPLY
The Keston is a room sealed appliance and therefore does not require purpose provided
ventilation to the boiler room for combustion air.
2.10COMPARTMENT INSTALLATION
The casing temperature of the Keston 130 is very low. Due to this fact, no compartment
ventilation is required for cooling purposes.
2.11CONDENSATE 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 15mm internal diameter within the
dwelling. Condensate should preferably be drained into the sanitary waste system or,
alternatively, the rainwater system of the property.
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 1 in 20 is essential. Freezing of the
termination and pipework must be prevented. Any drainage pipes outside the property
must be at least 32 mm inside diameter.
2.12RADIANT FLOOR HEATING
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
o
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 maximum operating
temperature can be lowered accordingly by introducing a supplementary control
thermostat within the control system of the installation.
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.
2.13LOW 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.
2.14DETERMINE 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
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
condensing boiler will still deliver significantly higher efficiencies 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
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.
Read Chapter 2 - Boiler Location and decide upon the position of the boiler.
Installation of the boiler is straightf orward but consideration m ust be given to access to allow f lue
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.
3.1WALL MOUNTING BRACKET
aPlace the bracket on the wall
horizontally with the pre-drilled
holes at the bottom.
bDrill through the centre hole of
the bracket, plug the hole and fix
in position.
cUsing a spirit level make sure
the bracket is completely level
and mark the position of the
other screw holes.
93
All dimensions in mm.
dRemove the bracket and drill the
holes in the positions marked.
Plug these holes.
eScrew the bracket to the wall
using screws of an appropriate
size for the wall type (No. 12 x 2
inch wood screws normally
suffice).
fMark the bottom fixing hole and
drill for a No 8 x 1 inch wood
screw. Insert plug.
3.2MOUNTING THE BOILER
aLift and locate the upper rear lip on the boiler to the boiler wall bracket.
bMove the boiler sideways to centralise the boiler on the bracket.
cScrew in the lower fixing screw.
3.3ASSEMBLY 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.
280
250
Figure 3.1 Wall Mounting Fixing Locations
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 burners outer mesh. The filter element supplied with the boiler is obtainable from
Keston Boilers or its distributors.
3.4INSTALLING FLUE AND AIR PIPES
Remember the flue pipe must
achieved using 92.5
o
bends.
slope downwards back towards the boiler and this is best
aFrom 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.
bDrill the two holes in the wall/ceiling, preferably using a core drill.
3.4.1Diameter of holes.
i)Allowance must be made for
socketed lengths if these are
to be passed through the
holes :
T
D
du = unsocketted
diameter
= 56 mm
ds= socketed
diameter
L
= 65 mm
d
u
ii)For 'horizontal' runs of flue
pipe the holes must either be
oversized or cut at a 5
(the latter may be difficult on
long holes).
3.4.2Oversizing
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.
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
connecting couplings.
Fully Engaged
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. Brackets should be placed at intervals
of approximately 1m.
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.
3.5CONDENSATE 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.
Adhesive
FA
Details are provided in Chapter 2 - Section 2.11 Condensate Drainage
Connection : 22 mm plastic pipe.
3.6WATER 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: 35 mm compression X 35 mm compression.
3.7GAS SUPPLY
Connect the gas supply to the appliance. Details of gas supply requirements are given in
Chapter 2 - Section 2.6 Gas Supply. Supply of adequate gas pressure
(with the boiler
running) is critical to ensure reliable operation of the boiler.
Connections: 0.75 inch BSP male.
3.8ELECTRICAL SUPPLY
NB:This boiler includes an optional timed (2 minute) pump over-run facility. If this
pump over-run facility is not required the pump may be wired externally to the
boiler.
The entry point(s) for the electrical supply cable(s) is in the base of the appliance (see
Section 2.2 Service Connections fig. 2.1.2) via two cordgrip bushes. Feed the cable(s)
through its 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.Supply wiring
should be in 4 core PVC insulated cable not less than 1.0mm
16 (material code H05VV-F). Pump wiring from the boiler pump connection
should be in 3 core PVC insulated cable not less than 0.5mm
2
to BS 6500 Table
2
to BS6500 Table
16 (material code H05VV-F).
3.The permanent live supply connection may be via a 10 amp fused double pole
switch, serving only the boiler. (Refer to Chapter 2 - Section 2.4 Electrical Supply).
The system controls and 2A switched supply for the boiler must also be supplied
via this isolator.
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 supply cable(s) must be connected to the main terminals as follows:-
N-Blue wire (Neutral) for 10A permanent and 2A switched
The pump cable must be connected to the pump terminals as follows:-
N -Pump neutral wire (blue)
L-Pump live wire (brown)
-Pump earth (yellow/green)
NB:The boiler circulating pump should not have a locked rotor current rating
exceeding 2A.
Ensure connection is made such that if the cable slips in its anchorage the current
carrying conductors become taut before the earthing conductor.
Optional Wiring Method:
Alternatively, the appliance may be controlled by a single 230V supply fused at
10A which is switched by external controls. This can be achieved by placing a link
wire between terminals marked PL and SL and running the single 10A switched
live supply to the PL terminal. In this way the boiler pump should be wired
externally to the boiler and will not enable the pump over-run facility.
3.9EXCHANGING 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.
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.
The guarantee provided with the Keston 130 does not cover damage caused by system
debris or sludge.
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
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. Full
details of this procedure are given in
Section 4.7 Checking The Gas Pressure.
GAS VALVE
This will ensure that combustion is good
enough to allow combustion fine tuning to
take place.
Combustion Fine Tuning
It is advisable on all
combustion quality is checked by
measuring the carbon dioxide (CO
oxygen (O
), level. This procedure is
2
detailed in Section 4.9 Combustion Fine
Tuning. Badly tuned combustion will lead
installations that the
), or
2
Burner pressure
Adjustment
Burner pressure
test nipple.
to reduce the life of the boiler and
invalidate the warranty.
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.
4.1INITIAL 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
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. Boiler failure due to
system debris or sludge shall invalidate the guarantee.
link the flow and return pipes on the 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
4.2GAS SUPPLY
The complete gas installation up to the boiler service cock must be checked for
soundness. BS 6891.
4.3ELECTRICAL INSTALLATION
Carry out preliminary electrical safety checks, i.e. Earth continuity, Polarity, Resistance to
Earth, Short Circuit using a suitable test meter.
4.4LP 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.
4.5INITIAL 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.
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.
c.Turn the gas service cock to ON.
d.Turn on the electrical supply, setting any external controls to call for heat.
e.Set the boiler On/Off switch to “ON”. The amber 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 light gas at the main burner, 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 green (run) lamp, the upper lamp adjacent to the
flame symbol, will also be illuminated indicating successful ignition (If it does not
and the green lamp is extinguished after 10 seconds, air is indicated - turn off and
repeat the procedure).
If ignition 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.
f.Check for gas soundness between the gas service cock and connection to
the burner manifold.
4.6HOT 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. For sealed
systems, fill to the required Initial Design Pressure.
4.7CHECKING 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
on the databadge by turning the exposed
burner pressure adjustment screw
(clockwise will increase burner pressure,
anti-clockwise will decrease burner
pressure). This will ensure that
combustion is good enough to allow
combustion fine tuning to take place.
Replace the brass dust cap to cover the
burner pressure adjustment screw.
4.8TIMING THE GAS METER NATURAL GAS
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 3% 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.
The Keston 130, when correctly set, should take 51.8 seconds for 2 cubic feet of natural
gas and 91.5 seconds for 0.1 cubic metres of natural gas (assuming 1038 btu/h per cubic
foot). 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.
Fig 4.7
GAS VALVE
Burner pressure
Adjustment
Burner pressure
test nipple.
4.9COMBUSTION FINE TUNING
Although the gas pressure is preset at the factory differing flue arrangements may require
fine tuning of the gas pressures to produce the best combustion and ensure long burner
life. It is advisable to check proper combustion by measuring gas input and the level of
carbon dioxide, or oxygen, in the flue outlet from the boiler. Overfiring or underfiring the
burner will reduce the longevity of the appliance.
Carbon dioxide is a colourless, odourless gas produced by all combustion processes.
When the Keston condensing boiler is operating properly carbon dioxide (CO
between 8.2 and 8.9% CO2 for natural gas.
be
To measure CO2 levels in the Keston boiler remove the 1/8" plug from the flue outlet pipe
inside the boiler (Figure 5.7.2 item 69). Insert the probe of a combustion analysis meter
and sample the gases as instructed in the test equipment's instructions.
If the CO2 levels need raising increase the gas output by turning the brass screw, under
the metal cap in the front of the gas valve, clockwise. Reduce CO2 levels by turning this
screw anti-clockwise.
If CO2 levels do not respond to adjustments the burner is probably running with too much
gas pressure. If, for instance, a clockwise adjustment to the brass screw in the gas valve
produces a decrease in CO2 the burner is too fuel-rich and not enough oxygen is present
for proper and complete combustion
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.
When the external controls are calling for heat, power will be fed to the boiler connection
strip at terminals PL (Permanent Live), SL (Switched 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 pins 1
& 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 will pause for approximately 10 seconds
and then attempt to re-ignite the unit. If this attempt fails, i.e. due to continued
lack of gas supply, the boiler will make two further attempts to ignite at intervals of
approximately 1 minute and will then go to a lockout state (red lamp illuminated
only). Once the gas supply has been resumed the boiler can be reset by turning
the boiler off and then on again 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.
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
qualified 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 servic ed. 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.
6.1Pre-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 removing the screws retaining the top of the door
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
o
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
o
C) check
that the condensate flows freely from the condensate line.
6.1.1Burner & 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 between 10 mbar and 14 mbar (lowest
value represents a new appliance). If not clean the burner.
v)Turn off the electrical supply to the boiler.
Installation & Servicing InstructionsPage : 38
Page 42
WD52/0/1997Chapter 6 : Servicing The Keston 130 Condensing Boiler
Pressure Test
Point B
Burner Heat (From Above)
Pressure Test
Point A
Heat
Exchanger
Shell
Fig 6.1.1 Pressure Test Point Locations
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.
Flue
Flue Overheat
Thermostat
Combustion
Test Point
&
Pressure Test
Point C
viii)The pressure difference should be between 9.5 mbar and 13.5 mbar
(lowest value represents new appliance). 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 3.5 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.
6.2Recommended Routine Service
a.Inspect the air filter located at the top right hand side of the boiler. Release the
toggle catch on the filter tray and remove 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.
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
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 clean by flushing through with
clean running water.
f.Check the electrode mounted on the burner head. If the point is damaged or
burnt replace it.
Check that the spark gap measures 4 mm.
g.Replace the burner head, renewing the gasket if 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.Visually inspect the burner through the glass spy hole at the burner head (a small
mirror will prove useful).
j.Recheck the burner pressure by following the procedure detailed in Section 4.7
k.Remove the combustion test point plug from the flue pipe. This is situated around
150mm (6ins) from the bottom of the flue elbow at its connection to the heat
exchanger.
l.Using an approved combustion tester sample the flue products via the
combustion test point. CO
levels of between 8.2% and 8.9%, for natural gas,
2
should be observed. If such levels are not observed tune the combustion as
described in Chapter 4 - Commissioning. Also check the gas flow as detailed in
Sections 4.8 and 4.9
m. Replace the combustion test point plug.
n.Check all joints for soundness up to the gas burner.
Installation & Servicing InstructionsPage : 40
Page 44
WD52/0/1997Chapter 7 : Replacement Of PartsThe Keston 130 Condensing Boiler
7. REPLACEMENT OF PARTS
INDEX
7.0GENERAL
7.1PRECAUTIONS
7.2ACCESS
7.3PROCEDURES - GENERAL
7.4ELECTRICAL
7.4.1ON/OFF SWITCH
7.4.2BOILER THERMOSTAT
7.4.3NEONS
7.4.4FLOW OVERHEAT, FLOW HIGH LIMIT & FLUE PROTECTION
THERMOMSTATS
7.4.5WATER PRESSURE SWITCH
7.4.6IGNITION CONTROL BOX
7.4.7AIR PRESSURE SWITCH
7.4.8COMBUSTION BLOWER
7.4.9GAS CONTROL VALVE
7.4.10 GAS LOW PRESSURE SWITCH
7.5GAS ORIFICE
7.6SPARK IGNITION/FLAME DETECTION ELECTRODE
7.7BURNER HEAD & BURNER
7.8HEAT EXCHANGER
7.9AIR FILTER
7.10CONDENSATE TRAP
7.11PRESSURE GAUGE
7.12SIGHT GLASS
7.13HT IGNITION LEAD
7.14AIR ORIFICE
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7.0GENERAL
The following must always be carried out by a competent/qualified person.
7.1PRECAUTIONS
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.
WARNING :Parts of the boiler internal wiring will remain live even after turning
the boiler ON/OFF switch to the OFF position. Shut off the power
supply at the isolating switch before working on the appliance.
7.2ACCESS
i)Remove the front door by removing the three 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.
iii)Access to the rear of the control panel and base of the unit can be gained by
removing the control panel at the bottom of the boiler. Remove the two screws to
the control panel then gently pull the control panel free of the boiler casing. This is
secured by three press studs, two on either side and a central press stud at the
bottom of the control panel.
7.3REPLACEMENT 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.
7.4ELECTRICAL COMPONENTS
7.4.1On/Off Switch (Fig. 5.7.1 item 113)
i)Isolate the appliance (Section 7.1)
i)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)
v)Check for correct operation of the switch.
WD52/0/1997Chapter 7 : Replacement Of PartsThe Keston 130 Condensing Boiler
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 an advantage 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.
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 stainless steel disc
between thermostat and flue pipe. It is advised to use a small quantity of
leak sealant around the edge of the steel disc to prevent condensate
leakage from the flue.
vi)Reassemble (Section 7.3)
NB:When fitting the new thermostat it is an advantage 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.
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).
7.4.6Ignition Control Box (Fig. 5.7.1 item 106)
i)Isolate the appliance (Section 7.1)
ii)Gain access (Section 7.2)
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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
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.
7.4.8Combustion Blower (Fig. 5.7.3 item 78)
NB:This unit is heavy and must therefore be handled carefully when
replacing.
i)Isolate the appliance (Section 7.1)
ii)Gain access (Section 7.2)
iii)Disconnect the wires connecting the blower to the relay and pump
terminal strip (relay terminal number 6 and pump terminal 14)
vi)Remove the allen screws fixing the air intake pipe flange and the gas/air
mixture pipe flange to the blower.
v)Unscrew the three bolts fixing anti-vibration mounts to the combustion
blower through the base of the cabinet.
vi)Reassemble (Section 7.3)
NB:When reassembling inspect any gaskets for damage and replace
if necessary.
vii)Reset the gas rate (See Section 4 - Commissioning)
7.4.9Gas Control Valve (Fig. 5.7.3 item 91)
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 plastic air tube to the base of the gas valve.
viii)Remove the four allen screws securing the gas inlet flanged connections
to the gas control valve.
ix)Undo the four bolts fixing the base of the gas control valve to the gas
outlet block.
x)Remove the gas valve.
xi)Unscrew the gas low pressure switch at its connection to the gas control
valve body.
xii)Reassemble (Section 7.3)
xiii)Reset the gas rate (See Section 4 - Commissioning)
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7.4.10 Gas Low Pressure Switch (Fig. 5.7.3 item 101)
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)
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: Ensure that the injector is screwed fully home
viii)Reset the gas pressure (See Section 4 - Commissioning)
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 vi)).
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 4mm.
Distances above or below 4mm will affect 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 47 & 45)
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 14) and
remove the access panel from the top of the cabinet.
iv)Remove the two allen screws fixing the flange gas/air mixture pipe connection to
the burner head.
v)Remove the five allen screws fixing the burner head to the top of the heat
exchanger.
vi)Withdraw the burner & burner head from the top of the heat exchanger through
the access panel opening in the top of the cabinet.
vii)Unscrew the burner from the burner head taking care not to damage the burner
mesh.
vi)Reassemble (Section 7.3)
NB:When reassembling inspect any gaskets for damage and replace if
necessary.
Set the spark gap as detailed in Section 7.6
vi)Reset the gas rate (see Section 4 - Commissioning)
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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 front control panel (Section 7.2 (iii))
vii)Remove the boiler thermostat (Section 7.4.2)
viii)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.
ix)Remove the condensate trap (Section 7.10)
x)Remove the pressure gauge phial located next to the drain off tap.
xi)Remove the air filter (Section 7.9)
xii)Remove the two springs connecting the bottom tray of the air filter with the
cabinet top cover.
xiii)Disconnect the flow and return connections to the boiler and remove (cut) their
olives from the pipes.
xiv)Remove the push on flue and air connections to the flue and air pipes exiting the
top of the boiler.
xv)Remove the four screws fixing the cabinet top cover to the cabinet body and
remove the top cover.
xvi)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.
xvii)Remove the allen screw securing the top of the heat exchanger to its mounting
bracket.
xviii)Remove the heat exchanger, with pipework attached.
xix)Remove the flow, return and flue pipework from the heat exchanger
xx)Reassemble (Section 7.3)
xxi)Recommission (Section 4 - Commissioning)
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 the condensate trap pour water onto 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.
7.11PRESSURE GAUGE (Fig. 5.7.1 item 116)
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i)Isolate the appliance (Section 7.1)
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)
ii)Gain access (Section 7.2)
iii)Disconnect the flexible air intake hose from the air inlet manifold (Fig 5.7.3 item
85)
iv)Unscrew the air orifice grub screw (Fig 5.7.3 item 84) 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