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WD52/0/1997
1.1
DESCRIPTION
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 used 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 temperature of the air gas mixture is around 1800
combustion at an amazing 1000
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.
The boiler is suitable for connection to open vented or, preferably, sealed systems. The
system must be pumped central heating or pumped central heating with combined indirect
sanitary hot water. Gravity circuits must not be used.
Forming part of the boiler is the heat exchanger which is made from a highly corrosion
resistant stainless steel, formed into tightly wound coil. The hot combustion gases from
the central down firing burner pass through this coil imparting 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 faster when there is a call for heat. This
feature requires a higher water pumping 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 must be sized relative to the total calculated 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 sanitary hot water, if the system is
not hot water priority design. If there are special conditions such as excessive sanitary hot
water usage consult the manufacturer.
1.2
BOILER SCHEMATIC
Air is drawn into the boiler through a 50mm muPVC pipe. The air flow is proved by a
differential pressure across the air control orifice. Gas is mixed with combustion air at the
inlet to the fan. The gas flow is regulated by an orifice located in the housing downstream
of the gas valve.
The gas and air are thoroughly mixed in the blower and fed into the burner located at the
top end of the heat exchanger module. The gas and air mixture is ignited by a direct spark
ignition control system and burns with a blue flame just off the surface of the burner. As
the hot products of combustion pass downwards, they are cooled by exchanging heat with
the circulating water which enters the heat exchanger coil at the bottom of the heat
exchanger
Installation & Servicing Instructions
Chapter 1 : General Instruction
1. GENERAL INSTRUCTION
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The Keston 130 Condensing Boiler
C thereby reducing the NOx emissions.
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C but the Keston achieves
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