Hoval RoofVent CON-9, Design Handbook

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7 Alarms and monitoring
The Hoval DigiNet monitors itself. All alarms are entered
in the alarm list and displayed on the operator terminals.
Priority A alarms are also displayed via the collective trouble
indicator.
Caution
If the power supply for the DigiUnit terminal box
is interrupted, frost protection and monitoring are
not guaranteed. The only indication that a DigiUnit
controller has broken down is when it is no longer
displayed on the operator terminal. You should there-
fore check regularly that the display is complete.
Alarm Priority Cause System reaction Benefit
Frost A The temperature according to the
heating coil has fallen under 11 °C.
The mixing valve heating opens. Avoids interruptions of plant
operation and damage due
to frost.
The temperature according to the
heating coil has fallen under 5 °C.
■ The frost alarm is displayed.
■ The mixing valve heating opens 100 %.
■ The relevant indoor climate unit switches to
operating mode 'Off'.
Trouble with
heating/cooling
A The heat/cold supply is not available. DigiNet switches to the 'Off' operating mode. Avoids undefined operating
states.
Fans A A fan motor has overheated. The relevant indoor climate unit switches to
operating mode 'Off'.
Avoids damage to the
pump motor.
Fresh air damper A The fresh air damper is jammed or the
fresh air/recirculation damper actuator is
defective.
The relevant indoor climate unit switches to
operating mode 'Off'.
Prevents loss of energy /
undefined operating states
ER damper A The ER damper is jammed or the ER/
bypass damper actuator is defective.
If the fresh air temperature is less than 11 °C,
the respective indoor climate unit switches to
operating mode 'Off.'
Prevents loss of energy /
undefined operating states
Heating/cooling
pump, heat pump
A A malfunction has occurred at the
heating/cooling pump, the heat pump or
the gas boiler.
The relevant indoor climate unit switches to
operating mode 'Off'.
Avoids damage to the
pump motor.
Fresh air sensor B The fresh air sensor is defective. DigiNet operates at a fresh air temperature of
0 °C until the fault is eliminated.
Avoids interruptions of
operation.
Room air sensor B The room air sensor is defective. The DigiNet continues to work with the set
value as the room temperature until the fault is
eliminated.
Avoids interruptions of
operation.
Supply air sensor B The supply air sensor is defective
■
The DigiNet continues to work with a supply
air temperature of 20 °C until the fault is
eliminated.
■
The ER damper opens 100 %.
■
The supply air is directed horizontally
Avoids interruptions of
operation.
Extract air sensor B The extract air sensor is defective. – Avoids interruptions of
operation.
Isolation B The isolation switch on the unit has
been in the 'Off' position for more than
30 minutes.
– Avoids unintentional
switching off.
Filter B The set pressure difference for filter
monitoring was exceeded for more than
5 minutes.
– Informs the user of the
necessity of maintenance
work
Table L21: Alarms in Hoval DigiNet
Control systems
Alarms and monitoring