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11 - SAFETY FUNCTIONS
11.1. Defrosting function
When the unit is working in HEATING mode, the defrosting of the
outdoor coils is performed by cycle inversion in order to remove any
ice which has accumulated on them.
In 2-circuits units the defrosting procedure will be independent, i.e.,
the one will not start until the fi rst one fi nishes.
Defrosting is carried out in the following cases:
Defrosting by minimum pressure
When the pressure measured by the low pressure transducer
drops below 2,5 bar (by default).
Note: If the unit tries to perform a 4th defrosting operation in less
than an hour, this could be due to a lack of refrigerant caused by
a small leak or failure in the expansion valve, which means that
the control will trigger a low pressure alarm. This safety device
is reset manually.
Defrosting by diff erence with the outdoor temperature
The defrosting function is activated if the di erence between the
outdoor temperature and the evaporation temperature exceeds
16ºC (by default).
In addition to this condition, always it is necessary that:
- The outdoor temperature is lower than 10ºC.
- The pressure measured by the low pressure transducer is lower
than the initial value for defrosting, 5.6 bar.
- The time that must elapse from the last defrosting of the a ected
circuit has been excelled, 20 minutes.
- The time that must elapse from the last defrosting of another
circuit (units with 2 circuits) has been excelled, 90 seconds.
Note: There is the possibility of a defrosting by time (rescue
defrosting), so that if the pressure measured by the low transducer
is less than 5.6 bar for a time of more than 3 hours (180 min), a
defrosting is made without taking into account the di erence of
16ºC with the outdoor temperature (confi gurable by parameters).
Defrosting operation
Starting defrosting
If one of the last cases is met, once the delay has elapsed at the
start of defrosting, 120 seconds, the shut-down of the compressors
will be triggered.
The regimen will be changed 30 seconds after the compressors
are stopped, giving power to the 4-way valve. The compressors
will be started up after 15 seconds, so that they can perform the
defrosting procedure.
During the defrosting operation, the behaviour of the other unit
components will be as follows:
- The supply fan will continue to operate.
- the outdoor fans will be connected when a set pressure of 35
bar is exceeded, if the outdoor temperature is greater than
-5ºC. They will be disconnected if the pressure drops below 33
bar, the outdoor temperature drops below -6ºC or a maximum
connection time elapses.
This action enables prolonging the duration of defrosting and,
as such, the ice accumulated on the coil is completely removed.
In the case of 1-circuit units with an outdoor coil temperature
probe (optional) a special confi guration for the outdoor fans is
possible: they will be connected when a pressure of 28 bar is
exceeded and will not be disconnected until the pressure does
not drop below 26 bar, the temperature measured in the probe
is higher than 5ºC or a maximum connection time elapses. In
this case, the duration of the defrosting is also modifi ed (16
minutes).
11.2. Anti-fi re safety
When the return air temperature exceeds a safety value the anti-
fi re safety device will be activated (60ºC by default) and the unit will
stop. It will not return to operation until the temperature has dropped
to below 40ºC.
13.3. High supply temperature safety
In units with optional electrical heaters or gas burner, when the
supply temperature exceeds 55ºC, this optional will be shut down
and will not be reconnected until this temperature drops below 53ºC.
In units with fresh air damper it is possible to select the damper
position in the event of an anti-fire alarm or when the units
incorporates a smoke station (optional) connected to the digital
input DI2.
The following functioning logic must be selected to comply with the
French regulations on Fire safety (ERP).
In case of failure of the thermal protection of the supply fan, this
fan and all components are stopped, the fresh air damper is open
to 100% (return air damper closed). Manual reset.
Note: this safety is a priority to that of the A2L sensor.
In case of failure of the thermal protection of the electrical heaters,
all components are stopped and the supply fan after 120 seconds,
the fresh air damper is open to 100% (return air damper closed).
Manual reset.
CS01a
Anti-fire safety
french ERP: N
Damper status during
failure: OPEN
Delay shutdown ind.fan
with resist.:120 seg
CS01
Anti-fire safety
Set: 60.0
o
C
Difer.: 20.0
o
C
Damper status during
failure: OPEN
- The optional backup device incorporate by the unit can be
enabled: electrical heaters, hot water coil, gas burner or boiler.
- The fresh air damper (optional) will remain closed, except for
100% fresh air units.
- The electrical heater of the preheating module, optional for
100% fresh air units, will be activated.
- The rotary heat exchanger (optional) will operate. In this case,
the fresh air damper will remain open.
Note: control of compressors by minimum supply temperature is
stopped during the defrosting operation.
Ending defrosting
The following conditions must be met in order to end:
- By maximum time, after 10 minutes from the start.
- By pressure, when this exceeds 33 bar.
- By opening the high pressure switch. This alarm will not be
indicated.
When the defrosting operation ends, the compressors stops, the
four-way valve is reversed again and, after this, it will be possible
to restart the compressors by the normal pressure control.
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