English
Economizer
Supply
Temp.
Supply Setpoint
Supply Diff.
Normal Damper
opening
Normal opening / 2
Min Opening
0%
100%
FRHR control
Heating
Setpoint
FRHR_differential
FRHR_min
Room_air
temp
Secondary heater
and
thermodynamical
heating
14 SysAer
3.9. FRECO OPTION
This option can recover the heat released by the cooling systems used in sales spaces. A valve can control
the water flow in the corresponding coil.
This option can be activated on the user interface and can only be activated in heat mode.
The valve is controlled according to the temperature delta between the air temperature measured in
the room and the temperature setpoint. If the valve is fully open with an additional load request, the
thermodynamics circuits and/or the auxiliary heating take over.
3.7. THREE DAMPERS ECONOMIZER OPTION
For example, if the winter freecooling function opens the damper at 60% (normal opening), and the supply
air function closes the damper of 50%, the final opening will be 50% of 60%, that is to say 30%.
When supply air temperature starts to increase to the point of exceeding supply set point + differential, then both
the external damper and heating valve revert to normal operating mode (the minimum limit on supply air during
winter mode does not interact with compressor operation).
Winter mode
When supply air temperature drops below the supply set point + differential, the winter freecooling is
disabled, the heating valve is forced to fully open and the external air damper is gradually forced to close,
as illustrated bellow:
Summer mode
If the blast temperature drops below the blast set point, the outdoor air damper is gradually closed (
as in
winter mode
) and an operating compressor is switched off for a period of 10 minutes.
3.8. SUPPLY AIR TEMPERATURE MINIMUM LIMIT
The return blower is a part of the 3-Damper economizer option.
This fan is controlled in the same way as the main blast fan.
If the return blower cuts out, the unit is immediately stopped.
In de-frosting mode, the valve is opened at a definable value in the settings menu.
If the de-frosting contact of the FRECO battery is activated, the valve is fully open.
The Supply air temperature minimum limit protects the room against sudden drops in temperature and cold
air draughts.
