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.
3.7.3
System Pump Selection
(if
required)
The C36 Combi features an
integral circulating pump which
has sufficient excess head to
drive most domestic systems.
The available head is shown in
the graph below. If the system
index circuit resistance is in
excess of the available head
from the integral pump an
additional system pump will be
required.
The schematic below
illustrates
a
recommended approach
to using an additional
system
pump.
The
additional system pump
should
be
sized
to
overcome
the
index
circuit resistance only as
the boilers integral pump
will
overcome
boiler
resistance.
If an additional pump is
required the selected
pump must comply with
BS 1394. Provision must
be made in the system
design for control of the additional pump.
3.7.4
Filling The System
The boiler is supplied with an approved filling loop device. This filling device is designed to
enable initial fill and topping up of system pressure. The system should be set to a
pressure of between 1.0 and 1.5 bar. To display the system water pressure press the
“Installer” button, on the boiler fascia, repeatedly until the number 5 appears on the
display. After a few seconds the display will change to show the water pressure, in bars.
Using the filling loop set the pressure to 1.0 to 1.5 bar,
WD388/0/2004
Chapter 3 - Boiler Location
The Keston C36 & C36P Combi Boilers
Installation & Servicing Instructions
Page : 15
Additional System
Pump
(if required)
C
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IC
W
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(if required)
COMBI
HEATING CIRCUIT
KESTON
Expansion
Vessel
Drain
Cock
RETURN
FLOW
Permanently
Open 28mm
By-pass
C36 Com bi Available pum p head
0
1
2
3
4
5
6
7
0
5
1 0
1 5
20
25
30
35
40
F l o w R a t e ( l p m )
