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5.13.3 Checking the gas pressure switch
When the gas pressure switch is open the motor is not powered.
If, after a heat request, the gas pressure switch open, the motor
stops and:
if the gas pressure switch stays open for more than 2 minutes,
the fault is displayed by the diagnostic LEDs.
if the gas pressure switch stays open for less than 2 minutes,
the fault is not displayed.
when the gas pressure switch closes again, the motor is re-
started if also the air pressure switch is open.
when the gas pressure switch is closed the motor is powered
for about one second (to acknowledge the signal) and then it
is shut off for 2 seconds to be then restarted and start the
operation cycle.
If the gas pressure switch opens during normal flame operation,
the motor stops immediately, the gas valves are closed and the
full ignition cycle is repeated.
Up to 3 attempts are possible, at the fourth opening of the gas
pressure switch, the burner reaches the lockout condition.
The number of possible attempts to open the gas pressure switch
during flame operation is reset at every heat request, every
lockout, every power supply fault (see paragraph "Monitoring
the power supply voltage" on page 28) and every shut-down
test.
If the gas pressure switch opens during post-purging or during
continuous purging (if set), the motor stops and stays off for the
whole time that the gas pressure switch is open and the fault is
displayed immediately by the diagnostic LEDs.
5.13.4 Checking the air pressure switch
When the burner receives the heat request the air pressure
switch is checked and if it is closed (bonded) the motor does not
start and after 2 minutes the lockout condition is reached.
If the motor starts after a heat request, the air pressure switch
does not close within 15 seconds of pre-purging, the burner
reaches the lockout condition.
If there is a loss of air pressure after the first 15 seconds of pre-
purging but before the last 10 seconds, a recycle occurs (the pre-
purging time starts from when the air pressure switch closes in a
stable manner).
If after a recycle after a loss of air pressure there is a new loss,
the burner reaches an immediate lockout condition due to lack of
air.
If the loss of the air pressure switch occurs in the last 10 seconds
of the pre-purging time (before the start of the safety time) the
burner reaches an immediate lockout condition due to lack of air.
If there is a loss of the air pressure switch after the opening of the
first stage valves or during normal operation with flame, the burn-
er reaches a lockout condition within 1s.
The state of the air pressure switch does not influence the post-
purging time.
Se If continuous purging is set, the motor is powered even if the
air pressure switch is sealed but only in a condition without a heat
request or after 2 minutes if the lockout occurred after the heat
request.
5.13.5 Shut-down test
If the reset push-button or the remote reset is pressed during op-
erations for more than 5 seconds and less of 10 seconds, (to not
go to the successive menu) the burner switches off, the gas valve
closes, the flame goes out and the start-up sequence restarts.
Installation
If the switch off test is enabled, the number of repetitions of the
start up sequence (see paragraph "Recycle and limit of repeti-
tions" on page 27) and the number of possible resets (see par-
agraph "External lockout signal (S3)" on page 28), are reset.
5.13.6 Intermittent operation
After 24 hours of continuous operation, the control box starts the
automatic switch-off sequence, followed by a restart, in order to
check for a possible fault with the ionisation probe.
This automatic switch-off can be fixed at 1 hour, (see paragraph
"Programming menu" on page 31).
The modification of the parameter setting for intermittent opera-
tion takes effect if:
during the heat request, the switching off test function is ena-
bled;
there is a flame loss;
the heat request switches off and then later restarts;
the control box switches off and restarts;
the automatic restarting of the intermittent function occurs
(1hour/24hours).
5.13.7 Recycle and limit of repetitions
The control box allows a recycle function, i.e. complete repetition
of the start-up sequence, making up to 3 attempts, in the event
the flame failure during operation.
If the flame failure 4 times during operations, this will cause a
burner lockout. If there is a new heat request during the recycle,
the 3 attempts are reset when the limit thermostat (TL) switches.
By disconnecting the power supply, when a new heat request oc-
curs (power supply is applied to the burner) all possible attempts
at re-ignition are reset (maximum 3).
5.13.8 Presence of an extraneous light or parasite
flame
The presence of a parasite flame or extraneous light can be de-
tected in the stand-by state after a heat request.
If the presence of a flame or extraneous light is detected also in
the "t2" stage, the motor does not start until the flame signal has
disappeared or until lockout has been reached.
If after the fan motor starts, during the pre-purging, an extraneous
light or parasite flame is detected, the burner reaches the lockout
condition in 1 second.
If, during the recycle due to flame disappearance while operating
and the consequent repetition of the start-up sequence, the par-
asite flame or the extraneous light is detected before the motor
starts, the 25 seconds control countdown starts (for checking for
the presence of the parasite flame or the extraneous light) other-
wise the lockout occurs within 1 second.
The fault is indicated by the blinking LED (see paragraph "Fault
diagnostics - lockouts" on page 26).
When the heat request is finished, if the parasite flame stays on
the burner reaches the lockout condition due to parasite flame af-
ter 25 seconds (regardless of the presence or otherwise of the
post-purging or the continuous purging).
The parasite flame control is active even when there is a fault with
the mains voltage, the frequency, the internal voltage, the condi-
tion with gas pressure switch open.
The parasite flame control is not active only in lockout conditions.
27
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20135737
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