Ravenheat CSI 85 - Manual (Page 6)

SECTION 1
INTRODUCTION
1.1 The Ravenheat boiler is for the use of central
heating and domestic hot water combined
in one unit. It is fi tted with an automatic
domestic hot water priority valve.
A / (winter/summer) selector
switch is fi tted to the left hand side of control
panel.With the only (summer) position
being for domestic hot water.
position being for central heating
with domestic hot water priority. The boiler
is equipped with a front cover which can be
removed for servicing. The data badge with
technical data is placed on the lower right
hand side of the frame.
1.2 Fig.1.
Illustrates the general layout of components.
Fig. 2.
Illustrates the operating scheme described
in section 2.
SECTION 2
2.1 DESCRIPTION OF CONTROL SYSTEM
AND SEQUENCE OF OPERATION
2.2 Domestic hot water mode.
When the appliance is in rest mode with
the mains neon switch on.
Switch the summer/winter switch tap
position, with the heating circuit charged
with water (above 1 bar). If the domestic
hot water tap is turned on, the boiler will
function in the following sequence:
2.2.1 The pump starts.
The control board sensors.
The fan operates via the pressure switch and
sends a signal back to the ignition board that the
fan is running at maximum speed.
2.2.2
The spark ignition system is powered which in
turn commences the spark igniter to operate
and light the burner.
At this point the ignition board opens the gas
valve to light the burner.
2.2.3 When the electrode/sensor senses the signal
of the burner, the spark igniter stops.
2.2.4 From the minimum gas rate setting the
boiler increases to the maximum permissible
pressure over a period of 3 to 4 seconds and
will remain at its maximum required power until
it reaches maximum regulated temperature.
2.2.5 When the domestic hot water tap is closed the
diverter valve goes back into rest mode, the
main burner is shut down along with the pump
and fan which are also switched off.
The pressure switch returns to its rest mode
2.2.6 Central heating mode
2.2.7 If the switch is positioned on with
a demand for heat to supply radiators, with
6
the heating circuit fully pressurized so as
to operate the low water sensor device the
boiler will start in the same way in domestic
hot water mode but with slightly differing time
delay. In that it will start on minimum and
remain at this level for about 1 minute. After
which the fl ame will lift to its maximum setting
as governed by a potentiometer which range
rates the heating circuit between maximum
and minimum power. As the heating sensor
reaches temperature the gas burner
power modulates down, the fan speed
will also reduce to minimum fan speed.
When starting, the fan will always start at
maximum speed.
2.2.8 On the control panel are mounted two
potentiometers (thermostats) these control
the temperature. One is for domestic hot
water and the other for heating.
2.2.9 The boiler is fi tted with an anti-cycling device
on the control board. This delays the boiler
from re-fi ring over a 2/5 minute period when
in heating mode. The domestic hot water will
always take priority and is unaffected by the
anti-cycling device.
GENERAL FUNCTION
2.3 Central Heating Mode
2.3.1 A potentiometer installed on the electric circuit
board permits regulation of the boiler to partial
heating requirements, between maximum and
minimum settings.
2.3.2 Air is drawn by the fan for combustion.
2.3.3 The fan also forces exhaust gas through the fl ue
to the outside, this creates a lesser pressure in
the sealed combustion chamber, thus sucking
in combustion air, through the inlet duct.
2.3.4 The boiler water temperature is automatically
controlled by a built in thermostat
2.3.5 Interior space temperature is set by the room
thermostat to be installed in the heating
system. The boiler already carries connection
terminals for this thermostat, as well as for a
timeclock.
The burner continues to operate until it is
stopped by the timer or one of the thermostats
2.3.6 When the internal C.H. temperature sensor
intervenes the main burner shuts down. The
fan stops but the pump continues to operate.
2.3.7 When the room thermostats intervene the
main burner shuts down. The fan stops and
the pump turns off.
2.3.8 The condensate trap is fi tted with a blockage
safety sensor. This prevents the boiler
operating should there be a blockage in the
condensate discharge trap.