3.9
EXCHANGING 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 C45, C40P and C55(P) condensing boilers contain 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 C45, C40P and C55(P) 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 and earth loop impedance using a suitable test meter.
Initial Firing
The gas pressure setting is factory adjusted to within the required range and does
not need readjustment. 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
(minimum 18 mbar required for Natural Gas and 31 mbar required for LP gas). If all joints
are sound and the gas inlet pressure is satisfactory set the gas pressure check the gas
input. Full details of this procedure are given in Section 4.9 Timing The Gas Meter.
Combustion Testing
It is advisable on all installations that the combustion quality is checked by measuring the
carbon dioxide (CO
2
), or oxygen (O
2
), level. This procedure is detailed in Section 4.7
Combustion Testing. Badly tuned combustion will lead to reduce the life of the boiler and
invalidate the warranty.
WD536
Chapter 3 : Installation
The Keston C45, C40P,C55 & C55P
Installation & Servicing Instructions
Page : 22