Range Guide

School Project:
3 Keston 170’s on a rig
The Keston Condensing Boiler uses premix combustion technology which requires
adequate gas supply pressure and flow at all times during operation. Care should
therefore be taken to ensure that the supply, meter and distribution pipework is correctly sized for the gas flows required.
Details of gas consumption are provided on the back page of this brochure.
Flue SYSTEM DESIGN
The Keston commercial condensing boiler range use high
powered combustion blowers that enable flueing over
exceptional distances using small diameter plastic flue pipe
and fittings.
The exceptionally high efficiency of the units ensure very low
flue temperatures which permits the use of such low cost
plastic pipe for the flue duct. A second plastic pipe carries
combustion air from outside the building enabling the boiler
to be installed in a room without ventilation for combustion
air purposes. Boiler room combustion air ventilation is
therefore not required for a Keston commercial installation.
Design
For combustion air supply and flue exhaust individual air supply
and flue outlet pipes are used. The material used for flue outlet
&/or air inlet must be 50mm muPVC (BS5255) waste pipe for
the Keston 130 and Keston 170. Keston Composite pipe of an
internal diameter not less than 100mm is required for the
Keston 260 and Keston 340 models. Suitable pipe and fittings
can be obtained via Keston Boilers Ltd appointed distributors.
Both flue outlet terminal and air inlet terminal are supplied
with each boiler.
Minimum & Maximum Lengths
The flue outlet and air inlet pipes must have lengths of at
least 1m each.
The maximum lengths of both air inlet pipe and flue outlet
pipe, when no bends are used, are as detailed.
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.
A 92.5° sweep elbow is equivalent to 1.0m straight length.
Boiler
Air
Flue
Example
Air inlet uses one 92.5 sweep elbow. Hence, for a Keston 130 or 170 maximum
length permissible = 15.0m - 1.0m = 14.0m.
For a Keston 260 or 340 maximum length permissible = 20.0m - 1.0m = 19.0m.
Flue outlet uses one 92.5 sweep elbow. Hence, for a Keston 130 or 170
maximum length permissible = 30.0m - 1.0 m - total air inlet length = 29.0m -
total air inlet length.
For a Keston 260 or 340 maximum length permissible = 40.0m - 1.0m - total air
inlet length = 39.0m - total air inlet length.
5
Keston 130 & 170 Keston 260 & 340
Maximum Air Inlet Length 15.0m 20.0m
Maximum Flue Outlet Length 29.0m 39.0m
Maximum Combined Air Inlet 30.0m 40.0m
and Flue Outlet Length
Electrical CONNECTION
Electrical supply and control of the Keston condensing boiler is dependent on model as follows:
● Keston 130 and 170 10A permanent live, 2A switched live on/off control.
Shunt pump overrun control.
● Keston 260 and 340 13A permanent live, volt free link on/off control.
Gas SUPPLY