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For units not equipped with integrated electric
resistance, a duct modulating electric resistance is
available as a preheating accessory.
• Without Electric Resistance
In case the unit is without an electric antifreeze resist-
ance, the unit has preventive operation logic which,
below -5°C, automatically sets running of the intake
fan at minimum for 10 minutes every hour.
Also, in case the temperature falls below -10° C, the
unit stops automatically and an alert appears on the
display of the controller: "
When the Frost alarm is triggered, the unit switches
OFF and restarts automatically when the critical
climatic condition disappears. The Frost alert remains
until the next time the unit is switched off and back on.
Antifreeze protective circuit chart
UNITS
EQUIPPED
WITH
ANTIFREEZE
SYSTEM
UNITS WITHOUT
the input fan is brought to minimum speed for 10min an hour
ANTIFREEZE
SYSTEM
ALL
UNITS
When the Frost alarm is triggered, the unit switches OFF and restarts automatically when the critical climatic condition disappears.
The Frost alert remains until the next time the unit is switched off and back on.
FROST ".
Antifreeze electric resistance switch on
Setpoint t 4 =4°C
Electric resistance shutdown
Activation of preheating water coil valve
or ON/OFF resistance
Valve closure or ON/OFF resistance shutdown
Speed reduction of both fans
with proportional law with decreasing t 4 .
Electric resistance malfunctioning alarm
Unit switch off with "Frost" alarm
Defrost cycles:
Unit switch off with "Frost" alarm
Input air low temperature alarm
Unit switch off with "Frost" alarm
• With preheating Hydronic Coil or ON/OFF
resistance
As an alternative to the use of versions with the
electric preheating resistance, a hot water or ON/OFF
resistance pre-treatment coil can be used to perform
the antifreeze function, mounted on the outdoor air
inlet duct.
The hydronic coil or ON/OFF resistance is not available
as an accessory. However if the configuration DIP
SWITCHES 2 and 3 are activated, the power board
is capable of managing the opening of an on/off
valve or an ON/OFF electric resistance stage for the
preheating function.
The valve opening and closing logic is shown in the
table below.
The opening of the water supply valve of the coil is or
of the ON/OFF electric resistance stage is represented
on the display with the icon
External
air t
1
<-3°C
–
>0°C
<-3°C
–
–
<-3°C
<-3°C
<-20°C
<-5°C
<-10°C
–
–
English
.
Supply
Exhaust
air t
air t
2
4
–
<4°C
–
<1°C
–
–
–
<3°C
–
<1°C
–
>6°C
–
<3.5°C
–
<1°C
–
–
–
–
–
–
<10°C
–
<5°C
–
43
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