Technical data

22
7.1 CHECKING APPLIANCE OPERATION
When carrying out any repairs or servicing to the
appliance, the relevant commissioning and/or
set-up procedure must be undertaken to ensure
the continued safe operation of the appliance.
Particular attention should be made to ensure
gas soundness, water soundness, and the
electrical integrity of the appliance.
7.2 APPLIANCE MODE OF OPERATION
7.2.1 START-UP
When power is first supplied to the appliance it
will go through a self-purge procedure whereby
the pump and fan will be momentarily energised.
The boiler will then operate in either one of the
following modes:
● Stand-by
● Heating mode
7.2.2 STAND-BY
When there is no demand for heating or hot
water. And the appliance remains inactive for a
period of 24 hours, the pump will be energised for
a few moments to prevent it from seizing. Should
the flow temperature sensor fall below 7 °C the
pump will be energised. If the flow sensor
temperature falls to below 3 °C the burner will be
lit and the appliance will operate at the minimum
output until the temperature of the flow sensor
reaches 10 °C, whereupon the pump will continue
to run in pump over-run mode.
7.2.3 CENTRAL HEATING MODE
When there is a request for heat via the time clock
and/or external controls the motorised valve and
pump will go through a self-test function this is to
ensure correct operation and valve configuration.
Once the self-test function is complete, the pump
and fan will be activated via the flow temperature
sensor. When the fan is sensed to be operating
correctly, the ignition sequence commences. The
speed of the fan and therefore the output of the
boiler is determined by the temperature of the
water sensed by the flow & return temperature
sensors, consequently a high temperature at the
flow sensor results in a lower fan speed. As the
water temperature increases, the temperature
sensors – located on the flow and return pipes of
the boiler – reduce the fan speed via the electronic
circuitry. Depending on the load, either the water
temperature will continue to rise until the set point
is achieved or the water temperature will fall
whereby fan speed will increase relative to the
output required. When the boiler has reached the
set point, the burner will switch off. The built-in
anti-cycle device prevents the burner from re-
lighting for an adjustable period of time (factory
default is 92 seconds). When the temperature of
the flow sensor falls below the set-point, the
burner will re-light.
7.3 SERVICE PARAMETERS (5 – 42)
To check or adjust the service parameters, you
must first access the service mode.
To access the service mode:
SECTION 7 CHECKS, ADJUSTMENTS AND FAULT FINDING
● press and hold the
mode
and
S
buttons
simultaneously for 2 seconds;
● when “COdE” appears in the display, press
S
again, “C” should now be shown on the left
side of the display, with a random number on
the right side of the display;
● using the
+
or
-
buttons, scroll until “05”
is shown in the right side of the display;
● press
M
to store the code;
● press to exit the sevice mode.
7.4 ADJUSTING THE GAS VALVE
The gas valve must be set-up or adjusted with
the aid of o properly calibrated flue gas
analyser.
Isolate the appliance from the electrical supply and
remove the appliance casing as described in section
4.10. Unclip and remove the front air chamber cover.
Set the flue gas analyser to read CO
2
and insert
the probe into the flue analysis test point (fig. 1).
Restore the electrical supply to the boiler and
generate a request for central heating via the
room thermostat and/or timer.
Press the
mode
and
-
buttons at the same
time, the boiler will now run at minimum power for
15 minutes.
Consequently, by pressing the
mode
and
+
buttons at the same time, the boiler will run on
maximum power for 15 minutes.
7.4.1 MINIMUM SETTING
With the boiler operating at minimum output the
CO
2
reading should be 9.8% (+/- 0.2%). If the CO
2
reading is correct, proceed to section 7.4.2. If the
CO
2
reading is incorrect, the minimum gas
pressure must be adjusted as follows:
● Using a suitable screwdriver, very slowly turn
the minimum adjustment screw (fig. 30) –
clockwise to increase, counter clockwise to
decrease – until the correct value is displayed
on the CO
2
analyser (allow time for the analyser
to stabilise).
● Using the procedure detailed in section 7.4,
change the fan speed momentarily from
minimum to maximum, then back to minimum.
● Check that the correct value is still being
obtained. If not, repeat the above procedure.
7.4.2 MAXIMUM SETTING
The maximum setting must only be checked and/
or adjusted after the correct minimum setting has
been verified. Using the procedure detailed in
section 7.4, change the power from minimum to
maximum.
With the boiler operating at maximum output the
CO2 reading should be 9.8% (+/- 0.2%). If the
CO2 reading is correct, press the
+
and
-
buttons at the same time to return to the normal