User Instructions

2.6.7 Pump Selection
The Keston 260 and Keston 340 boilers are supplied complete with integral boiler
shunt pumps. However, these pumps are sized purely to provide adequate flow
rate through the boiler at the pressure drop caused by the boiler itself. No
allowance has be provided in the shunt pump size for system resistance.
A system pump(s) should therefore be selected sized to provide the required
system flow rate at the pressure drop created by the system index circuit.
2.7 FLUE SYSTEM
2.7.1 Design
Individual air supply and flue outlet
pipes are used. The material used
for flue outlet &/or air inlet must be
Keston Composite pipe of an
internal diameter not less than
100mm. Suitable pipe and fittings
can be obtained by Keston Boilers
Ltd via its appointed distributors.
Both flue outlet terminal and air
inlet terminal are supplied and are
illustrated in Figure 2.7.1.
Although the flue outlet and air
inlet terminals are identical great
care must be taken to ensure that
the air intake terminal is positioned
facing downwards or in such a way
as to ensure rain cannot enter the
air intake pipework. Boiler damage due to water entry through the air intake
pipework is not covered under the appliance warranty.
2.7.2 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 below.
Minimum Flue Length : 0.5m
Minimum Air Intake Length : 0.5m
Maximum Air Inlet Length : 20.0 m
Maximum Flue Outlet Length : 39.0 m
Maximum Combined Air Inlet : 40.0 m
and Flue Outlet Length
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
o
sweep elbow is equivalent to 1.0m straight length.
WD53/0/1999 Chapter 2 - Boiler Connections The Keston 260 & 340 Condensing Boilers
Installation & Servicing Instructions Page : 9
Figure 2.7.1
Terminal Design