22
Installation and operation manual
–
DTH-V9-2020
Step 8 -
Post-purge (S100)
This step is allowed when the burner modulation request is lower than 2.3V DC for more than the
low fire delay, if the heating demand is turn OFF or if an alarm has been detected with the burner
operation.
The burner is stopped, the modulating gas valve close and the blower speed is set to 100% for 60
seconds approximately in order to purge the heat exchanger.
After the post-purge delay, the sequence returns to the
standby
step. But if an alarm is active, a
manual reset is required on the HMI touch screen. When the alarm is cleared the sequence can be
started again.
Depending on the step when the alarm is detected, the
standby
or the
post-purge
steps will be
executed:
•
The Stand-by step
is performed if an alarm has been detected during the execution of
safety
verification
or
pre-purge
step.
•
The Post-purge step
is performed if an alarm has been detected when the
Burner ignition
is
activated or after.
