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47
AST 14 C 257/00
Logic diagram for boiler operation
Venti latore di c om bustione
ON/OFF
Elettrovalvola
Pressostato aria
Term ostato fum i
Ac c ensione
Rilevazione
Blocc o
Tem po veri fi ca pressostato aria
o term ostato fum i
TW tem po di attesa
Acc ensione
del brucia tore
Bruc iatore ac c eso
funzionamento norm ale
Tem po di sic urezza Ts
Bloc c o
Funzioni
Te mpi
The flame control adopts the flue gas shutdown status if the flue gas probe and
thermostat do not provide the consent needed for correct operation (see page 71).
DHW CONTROL
With the boiler in DHW or DHW+HEATING mode, closing of the electrical contacts of the
DHW priority flow meter generates a request for DHW operation, leading to DHW
modulation.
The DHW request takes priority over all other requests and ends when said electrical
contacts re-open.
IMPORTANT. With parameter P15, DHW flow meter reading can be delayed (from 0
to 3 seconds).
PLATE DHW MODULATION (
solo versione KC con P3=1)
Following a request in plate DHW mode with the boiler on DHW or DHW+HEATING, the
automatic flame control section starts the burner ignition sequence if the water
temperature read by the DHW probe is lower than the set-point value + 3°C. At the end of
the sequence, the power provided to the burner corresponds to the ignition power (P6),
and the power to the burner corresponds to the flame modulation value.
The DHW temperature is read constantly, and the ramp is interrupted when the flame
modulation point is reached, which takes place with a PID-type action, until the DHW
temperature pre-set on the boiler or the remote control is reached and maintained.
During the first 20 seconds DHW drawing, to prevent the boiler continually switching on
and off for brief requests, the maximum temperature allowed by the DHW probe for burner
switch-off is set at 15°C more than the set-point. The burner re-ignites when the
temperature drops below the set-point +8°C.
Shutdown
Detection
Functions
Switch-on
Flue gas
thermostat
Solenoid
valve
Combustion fan
Time for checking air pressure
switch or flue gas thermostat
TW standby time
Burner switch-on
Burner ON-normal
operation
Safety time TS
Shutdown
Times
