30
DOMITOP HF 24 - 30 E
FERELLA GOLD HF 24 - 30 MEL
Version - 09.2002
3. OPERATION
3.1 Operating principle
When there is a call for heating, the circulator and fan start working; then the air pressure switch enables the
control and safety unit to ignite the burner. Via the electronic flame modulation system, the boiler capacity
is gradually metered till it reaches the set delivery temperature. If the power needed for the heating plant is
lower than the minimum boiler power, when the delivery temperature exceeds the setting of 6°C, the burner
switches off and the electronic system enables re-ignition only after another 2 minutes. On reaching the set
ambient temperature (room thermostat), the burner switches off and the circulator keeps on working for
another 6 minutes to enable better heat distribution throughout the system.
Test function
Bridging the terminals of connector X5 turns on Test operation. In this mode the boiler works as in heating
mode, but idle time and modulation are turned off. The test lasts 5 minutes.
Post-circulation
After the call for heating, the circulator performs post-circulation for approximately 6 minutes to prevent
thermal inertia and balance the system boiler temperature.
Circulator anti-locking
If not used for 24 h, the circulator is turned on for a few seconds to prevent it locking due to an extended
stoppage during summertime operation.
Gradual starting on heating
(gradual increase in heating temperature)
The time to reach the maximum heating temperature is 5 minutes.
Limit thermostat
The 88°C limit thermostat coming on causes the burner to switch off momentarily via the ignition unit and
the heating circulator to start up.
Antifreeze protection
The antifreeze function is turned on by the heating temperature sensor when the temperature falls under 5°C.
In this phase, both the burner and the circulator start working. When the temperature reaches 15°C, the
burner switches off while the circulator keeps on working for another 6 minutes.
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