5. Protective safety
functions
The heat exchanger’s freeze protection
The heat exchanger is equipped with a reliable
freeze protection function that guarantees
continuous and balanced ventilation in the
home even during extreme conditions. If there
is a risk of the heat exchanger in the ventila-
tion unit freezing, the preheater is activated,
the speed of the fans is changed if necessary
and the heated extract air prevents freezing
inside the heat exchanger.
Electric air heater
An automatic thermal overload cut-out
switches off the air heater if a fault situation
arises. This protective device automatically
resets itself when the air heater has cooled
down.
The overheating protection that requires
manual resetting can be reset by pressing a
button located inside the ventilation unit. The
location of the push buttons on the ventila-
tion unit is marked with a circle in the images
to the left. When you press the reset buttons
and feel a click, the overtemperature protec-
tion (thermal overload cut out) has then been
reset.
The “Re-heater fail” alarm appears on the
screen if the overtemperature protection
trips. The alarm disappears when the fault is
acknowledged.
The fans’ thermal overload protection
The fans have thermal overload cut outs,
which stop them if the temperature rises too
high. The controller also stops the fans if a
serious malfunction occurs in the ventila-
tion unit. The protective function resets itself
automatically when the temperature drops or
the malfunction has been remedied.
On the Econo models, there is a
temperature sensor that protects the water-
heated air heater from freezing. The “Water
radiator freezing warning” alarm appears on
the screen if the temperature of the water
heated air heater drops too low, but the unit
continues to operate normally.
If the air heater’s temperature drops further,
Important
Freeze protection function
Ice can form in the heat ex-
changer during periods of cold
weather if the extract air is hu-
mid. A protective function then
automatically reduces the speed
of the supply air fan. Under such
conditions, variations in the fan
speed are therefore normal.
Under such conditions, small
amounts of ice can form inside
the ventilation unit.
!!
the controller will stop the ventilation unit to
prevent the air heater from freezing. When
the temperature of the air heater has risen
sufficiently, the ventilation unit and panel
show a so-called remaining info-alarm, .
The Info alarm can be reset from “Alarm” on
the main menu.
NOTE! When there is a water-heated air
heater in the ventilation system (Econo model
ventilation unit or duct mounted air heater)
the system should be equipped with shut-off
damper so that the air heater cannot freeze
during a power failure.
Temperature sensors
If a sensor fault is detected, the ventilation
unit enters restricted mode to prevent dam-
age to the ventilation unit. The functions
related to the current sensor in question are
deactivated and the ventilation unit works as
well as possible. The ventilation unit's function
returns to normal once the fault has been
corrected.
Cold supply air
The ventilation unit has built-in condensa-
tion protection on the ventilation duct. If it is
discovered that the supply air is too cold, the
ventilation unit stops and an alarm is shown
the cooker hood.
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