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82
AST 14 C 255/00
Air pressure switch
(E03 shut-down for CTFS version)
The air pressure switch, fitted only in the forced draught models, is a normally open
contact connected in series with the gas valve, and is directly managed by the automatic
flame control. Its function is to detect a proper pressure difference in two different points of
the boiler and is directly managed by the electronic board.
The pressure switch contact must be open before fan is supplied with power, and closed
when it starts working. At the end of the request, when the fan is no more supplied with
power, the contact must re-open. Therefore, the board double-checks the contact opening,
one check is performed at the initial and one at the final phase.
When the pressure switch is open, the gas valve cannot be supplied with power.
After 10 seconds since powering the
combustion fan, if the pressure switch
contact is still open, a volatile shut-down
signal is generated. Said signal does not
need to be reset. The same shut-down
signal is generated if the pressure switch is
in a wrong position or in a waiting status.
The boiler will enter a non-volatile shut-
down mode only if the pressure switch is in
a wrong position for more than one minute
and must be reset.
Differential pressure switch CTFS 24 kW: 35/45 Pascal Pmax=1500 Pa
Differential pressure switch CTFS 28-32 kW: 125/112 Pascal Pmax=1500 Pa
Pressure transducer
(shut-down E04 and E09)
Its function is to constantly check the system pressure. If pressure is equal to or lower than
0.4 bar
,
a low pressure signal (error code E04) is generated. Besides, all requests of
operation with the pump will be ignored. Pump will be switched off. Also the multifunction
relay is de-energised if selection is P17=1 or 3. Signalling will be reset upon reaching 1 bar
during the filling phase
.
The transducer checks as well that the system does not reach a too high pressure.
Therefore, if pressure is equal to or higher than 2.8 bar,
the E09 fault is signalled without
interrupting any functions in progress. The error is reset when pressure is lower than 2.6
bar.
WARNING: all pressure limit values can be edited through the super-technical parameters
(see parameter list on page 37)
.
Boiler combustion chamber automatic recognition
(E72 shut-down)
The type of boiler (forced draught or natural draught) is automatically recognised each
time the board is supplied with power. The board attempts to read the inputs dedicated to
the air pressure switch or to the flue gas thermostat.
During such phase, “CHA” will appear on the boiler display and upon the following
recognition (which must take place within the first two minutes) the following message will
be displayed for 5 seconds:
