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71
AST 14 C 257/00
BRUSHLESS FAN CHECK
The fan speed is constantly monitored to check for any faults. On standby (fan in the home
position), if the speed exceeds 500 rpm for more than 30 seconds, a fan alarm signal will
be generated with consequent shutdown.
At the start of the rotation request, the speed read must be greater than 700 rpm, and
within the maximum set fan speed tolerance (set-point ± 300 rpm) in a minimum time of 10
seconds. Otherwise, a fan alarm signal will be generated, with consequent shutdown.
During operation, if the speed read is below the negative window (set-point-300 rpm), and
in any case below the minimum rotation speed for the operating fan (700 rpm), or greater
than the positive window (set-point + 300 rpm), for more than 30 seconds, the power
supply to the gas valve and igniter is disconnected. If the fault remains for more than 10
seconds, the fan alarm signal is generated with consequent shutdown.
At the end of the rotation request, the speed read must be less than 500 rpm in a time less
than 30 seconds. Otherwise, a fan alarm signal will be generated, with consequent
shutdown. The faulty fan signal is interrupted when the speed parameters acquired by the
HALL sensor fall within the pre-set limits.
FLOW ANTI-FREEZE FUNCTION
The flow NTC probe measures the temperature of the water in the boiler and when it falls
below 5°C, a request for operation on flow anti-freeze mode is generated, with consequent
burner ignition.
At the end of the ignition sequence, the output supplied to burner will be forced to the
minimum value. The request for operation on flow anti-freeze mode ends when the flow
temperature exceeds 30°C or when an operating time of 15 min is reached.
Any request for operation on heating mode has priority and causes the function in
progress to terminate.
During a flow anti-freeze function, the boiler pump activates and the three-way valve
switches to the heating position.
With P17 equal to 1 or 3, the multifunction relay is also energised.
If flame control shuts down and the burner cannot be ignited, the anti-freeze function
activates pump circulation with the multifunction relay active (if P17=1 or P17=3).
The flow anti-freeze function is enabled with all operating modes.
Important. The anti-freeze function only protects the boiler only not the heating system.
DESCRIPTION
ON
OFF
Flow anti-freeze function
5°C
30°C (
or after 15' of
operation )
General temperature tolerance
± 3°C
