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9.2.3
Central Heating Mode
In this mode the mode selector switch must be
turned to the
With all controls calling for heat the motorised
valve returns, mechanically diverting primary
water to the central heating circuit. The pump
and fan will run and the pressure differential
switch will be activated. This in turn will ener-
gise the electronic ignition control box. The
gas valve will be energised and the electrode
will start to spark.
If a flame is detected during the ignition at-
tempt period, (8-12 seconds) the sparking will
cease and the gas valve will remain ener-
gised. The appliance will light at 75% of maxi-
mum heat input for a maximum of 15 minutes
then increase to maximum output if required,
or will modulate during the 15 minute period if
the temperature rise is sufficient.
The temperature rise of the primary water is
sensed by the thermistor on the flow pipe.
As the temperature of the primary water ap-
proaches that set on the c/h temperature
control, the boiler will modulate as described
in domestic hot water mode.
On reaching the set temperature the gas
valve is de-energised and the burner is extin-
guished.
The appliance has an inbuilt delay timer and
re-ignition will not be attempted for approxi-
mately 3 minutes. This can be deactivated.
See page 58.
Constant monitoring of the temperature of the
primary water by the thermistor will regulate
the gas rate to maintain an average heat input.
When the appliance has reached the set
temperature and the burner is off, the pump
will continue to run to circulate the primary
water around the c/h system.
FAULT FINDING GUIDES
On the following pages are the fault finding guides. Be sure to read the notes below before begining
any fault finding
NOTES:
1.
To ensure correct fault diagnosis it is important that these guides are carried out in the set order.
2.
Check the electrical supply polarity is correct before carrying out fault finding (lockout will occur if the polarity
is reversed).
3.
To ensure that internal/external controls (if fitted) do not interfere with fault finding, disconnect the wires from
terminals TA & TA (labelling them in the process to ensure correct reconnection) and provide a solid link
between TA & TA.
Linea 24 & 28
position.
Temperature of the central heating is shown
at the temperature indicator whenever the
central heating is on.
If supply to the appliance is broken (e.g. by a
room thermostat or timeclock) the burner is
extinguished the pump stops, the motorised
valve is energised into the hot water mode
waiting for pre-heat or demand for hot water.
However, the fan will continue to run until the
primary water temperature is below 80 C.
Self Diagnostic Error Codes
The temperature indicator also serves as an
error code indicator. Should an error occur
the status LED (which is normally green) will
flash red. This will be accompanied by the
temperature indicator flashing an error code
of 01 - 07. Check code and proceed as
follows:
01: Failure to ignite (see 6.5.5). To re-set
turn mode selector switch to re-set posi-
tion for approximately 10 seconds, then
back to original position.
02: Overheat - Normally associated with ei-
ther poor or lack of primary water circu-
lation. Wait for appliance to cool then re-
set as described for code 01.
03: Problem with fan/flue. Re-set as de-
scribed for code 01.
04: Insufficient water pressure.
Check pressure and restore if necessary
(see 6.3.4). Reset as described for code
01.
05: Reset as described for code 01.
06: Hot water thermistor open circuit.
07: Primary thermistor open circuit.
33
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