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67
AST 14 C 258/00
POST-VENTILATION FUNCTION
At the end of a request for operation, the burner (if ON) is switches off immediately and the
fan remains powered on for 10 seconds (post-ventilation timer).
Any request for operation on CH, DHW, anti-freeze, chimney-sweep mode will have
priority, and the ventilation function in progress will be forced to end immediately.
The post-ventilation function is also activated when the water temperature read by the flow
NTC probe exceeds 95°C. It ends when the temperature is below 90°C. The post-
ventilation function is performed at the ignition speed (parameter P6) + 900 rpm.
Flow
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).
Important. The anti-freeze function only protects the boiler only not the heating system.
Plate DHW (KC only)
The DHW NTC probe measures the temperature of the DHW. When this value falls below
5°C, a request for DHW anti-freeze operation is generated. The pump activates and after a
30-second delay, the burner ignites with the output forced to the minimum value.
During DHW anti-freeze operation, the temperature read by the flow probe is kept
monitored, and if it reaches 60°C the burner switches off. The burner switches on again if
the request for anti-freeze operation is still present and the flow temperature is below
60°C.
The request for operation on DHW anti-freeze mode ends when the DHW temperature
exceeds 10°C or when an operating time of 15 min. is reached.
Any request for operation on DHW mode has priority, and causes the function in progress
to terminate.
During DHW anti-freeze operation, the pump is powered on, the electric diverting valve is
in DHW position and the multifunction relay (if P17=1 or P17=3) is in the home position. If
DESCRIPTION ON
OFF
Flow anti-freeze function
5°C
30°C (or after 15' of operation)
General temperature tolerance
± 3°C
