We reserve the right to make changes without prior notice
44
After enabling the air quality probe, the damper opening control is proportional. The damper starts opening at
its min. opening value as soon as the air quality setpoint (SpCO
2
) plus the neutral zone (NZCO
2
), if any, is
exceeded and it reaches its max. opening at the air quality setpoint (SpCO
2
) plus the air quality differential
(DCO
2
).
6.4.5 Damper opening control in function of condensing/evaporation pressure
In damper-equipped units, notably in some operating modes (e.g. washing cycle with compressors running,
management of air quality with compressors running), the request for external air damper opening may cause
the ingress of an excessive flow of air from the outside, which in some cases may undermine the refrigerant
circuit in the unit, both in summer and winter operating mode.
To prevent alarms from triggering in the refrigerant circuit, damper opening is controlled in function of a
condensing pressure threshold, when operating in summer mode, and an evaporation pressure threshold in
winter mode.
In summer mode, when the condensing pressure achieves the threshold value set in the controller,
opening of the external air damper is limited according to the condensing pressure and may be
modulating within a specific opening range that is set in the controller. This range is smaller than the
standard opening range (from min. to 100%) to reduce the return of external air.
In winter mode, when the evaporation pressure achieves the threshold value set in the controller,
opening of the external air damper is limited according to the evaporation pressure and may be
modulating within a specific opening range that is set in the controller. This range is smaller than the
standard opening range (from min. to 100%) to reduce the return of external air.
6.4.6 Heat recovery
If the unit is supplied with a static heat recovery unit, the controller can handle heat recovery, which helps
reducing energy consumption when the unit runs with frequent air changes and large energy consumption
levels.
The controller checks the operating conditions of the unit and manages the dampers in such way as to recover
a portion of heat from the expulsion air and to transfer it to the external air.
In summer mode, the condition required to enable heat recovery is met when the external air temperature is
higher than the expulsion air temperature. In winter mode, the condition required to enable heat recovery is
met when the external air temperature is lower than the expulsion air temperature.
Heat recovery is activated by means of an analogue output and a digital input during management of damper
opening.
When the conditions for recovery are met, the dampers are managed by the controller in such way that the
expulsion air and the external air flow through the static recovery unit.
The signal output to the dampers is related to the value set in the parameter indicating the necessary external
air amount. The signal may therefore be fixed, if there is no air quality probe fitted, or, if the unit is provided
with an air quality probe, the external air damper opening signal may be variable up to a max. value.
As soon as the conditions for free cooling or free heating are met, the signal that the external air damper in the
heat recovery unit sends to the bypass damper is switched with the help of the digital output.