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71
AST 14 C 258/00
Maximum flow and return deviation check function
(E80 shutdown)
Such check is carried out before each burner ignition request different from the
“instantaneous DHW” one.
After the pump activation, wait 10 seconds and then check the temperature differential
which must be between the range specified below:
∆
Tmin < ( Tflow – Treturn –
∆
T_Offset ) <
∆
Tmax
where,
∆
Tmin :
minimum differential value (- 8°C)
∆
Tmax:
maximum differential value (+ 8°C)
Tflow:
temperature read by the flow probe
Treturn:
temperature read by the return probe
∆
T_Offset:
probe error differential value (~ 0°C)
As soon as the calculated
∆
T is within the specified range, the burner receives the ignition
consensus. If this does not happen within 60 seconds, the check system forces the boiler
shutdown with consequent indication of the E80 error on the display (resettable by the
user).
During the E80 shutdown, the fan carries out a 6-minute post-ventilation cycle, and the
boiler pump enables its post-circulation function with deviating valve in the position
relevant to the type of request. The multifunction relay performs a post-circulation cycle if it
was excited before the shutdown.
Water flow
check function (E81, E82, E83 and E84 shutdown)
Such function is active only with burner ON, and constantly monitors the water flow inside
the primary exchanger.
Return probe
Double flow
probe
