Operating Description - Schwank infraSchwank D 15U Technical Manual

8 Operating description

Start-up
If heat demand exists, the fan will start up automatically.
A differential pressure arises in the burner box, which is
reported to the ignition unit via the differential pressure
switch.
After a pre-purge period of about 25 seconds the
automatic ignition starts (max. ignition time 5 sec.). The
twin solenoid valve with pressure regulator opens the
gas supply to the burner in 2 steps. The burner flame is
controlled by an ionisation electrode. The ignition is
switched off, if the ionisation electrode reports a flame
to the ignition and control unit within the safety time.
If the ignition process fails, the ignition unit repeats the
start-up for one more time.
Operation
A very long laminar flame is created in the first tube by
the special burner construction. The hot flue heats the
tube surface while being fed through the tubes by the
fan. The hot tubes emit long-waved infrared radiation
which is directed to the room by the reflector
construction.
The radiant tube infraSchwank D / calorSchwank D
work with a closed combustion system. The combustion
air is taken from the room or from the outside. The flue
is evacuated indirectly into the room or directly by the
exhaust pipe or by a special air/exhaust pipe system.
For optimal adaption of heaters´ performance to the
heat demand of the building heaters are offered in
2-stage or modulating operation.
Start and ignition of the heater has always to be in full
load. After a time of minimal 1 minute the heater can be
switched to small step.
.
infraSchwank D / calorSchwank D - shape U
Fault
If no flame is reported during the pre-purge period
(including 1 repetition of ignition process), the ignition
unit will switch off the radiant tube and will lock it.
Investigation and repair must be carried out by
authorized personnel only. After clearance of the
fault, the interlock can be reset.
The lock release can carried out by an interruption of
the electric power supply for 3 sec. A new start-up
begins. If no flame signal is reported to the ignition and
control unit during operation, the solenoid valve shuts
and stops the gas supply immediately. A new start-up
process is repeated.
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Troubleshooting: page 28
Monitoring of the combustion air supply
The combustion air supply is permanently controlled by
the differential pressure switch during the operation.
If the differential pressure switch is not in rest position
during the start-up the operation will not start. If the
operating contact is not closed during the pre-purge the
system will set in interference release.
If combustion air supply fails during operation (lack of
air), the differential pressure switch will close the gas
combination valve and stop the gas supply. A new start-
up process is to be repeated.
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