7
1.2.3 Operation of the storage
water heater.
Normal operation
When there is a demand for heat
a waiting period of about 1 second
elapses before the built-in spark
generator and pilot gas valve are
switched on. The ignition sparks ignite
the pilot burner and the resulting ame
is detected by the ionisation electrode.
Almost immediately after the pilot
ame is detected, sparking stops and
the main gas valve is openend. The
main burner is lit by the pilot ame.
The unit is now in operation. When the
temperature of the water in the unit
reaches the temperature that is set with
the thermostat, the thermostat switches
and disconnects the electrical heat
demand signal to the burner controller.
The gas valves are then closed.
Ignition failure
If the ame is not established within
the safety period the automatic ignition
controller locks out. The safety period is
about 25 seconds. Lock-out is indicated
by the lamp in the RESET-button on
the control panel. The unit has to be
manually reset by pushing the reset
button. If the ame is lost during normal
run, the automatic ignition controller
repeats the start sequence.
1.2.4 Combustion products
discharge safety device
The heater has been tted with a
combustion products discharge safety
device. It is the function of the safety
device to prevent ue gases from the
water heater entering the room where
the water heater has been placed,
instead of passing through the ue to
outside atmosphere. The gas supply
is disconnected as soon as the device
is activated by hot gases owing over
the sensor. After the cause of the re-
entry of ue gases has been traced the
device can be put back into operation
by pressing its reset button. If this
failure occurs frequently, this indicates
that the ue suffers from down draught
conditions. It is recommended that a
competent person carry out the necessary
remedial action.
Important
The combustion products discharge
safety device should never be put out
of operation. Re-entry of ue gases
to the building could be harmful and
cause poisoning or death.
