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 at the
bottom of the heat
exchanger.
The
optimum heat input is
detected by monitoring
flow
and
return
temperatures and is
adjusted by controlling
the speed of the fan.
The
optimum
pump
speed is also detected
and
automatically
selected by the boiler.
When the return water temperature is below 55
o
C, part of the water vapour in the
combustion products will condense inside the heat exchanger, thus increasing the boiler
efficiency
further
by
releasing the latent heat
of
condensation.
This
condensate falls to the
bottom
of
the
heat
exchanger where it is
separated from the flue
gases and exits from the
boiler
through
the
condensate drain. Any
condensate formed in the
flue runs back down the
flueway and is drained at
the base of the flue
connection to the heat
exchanger or drain points
within the flue.
The condensate is very
slightly acidic (about the
same acidity as vinegar)
and should be piped in a
plastic pipe. It is not
harmful to the waste
disposal system and may
be disposed of as normal
waste water.
The flue gases are piped
in a 50 mm muPVC
(BS5255
and/or
BSEN1566-1
and
BSEN1329) plastic or,
alternatively,
75mm
Keston composite plastic pipe to outside. The temperature of the flue gases are usually
WD388/0/2004 Chapter 2 : General Instruction The Keston C36 Combi & C36P Combi Boilers
Installation & Servicing Instructions
Page : 5
Boiler
Schematic
