EVCO S.p.A.
EV3 MVC & EVD MVC | Application manual ver. 1.0 | Code 144EV3MVI104
page 47 of 72
9.3 Activating free heating/cooling
This mode is activated if the room probe and external probe are activated and not in alarm.
If the external temperature is favourable this inhibits the recovery heat exchanger (bypass or deactivation) so as to use the external air
to improve the room comfort.
If the controller detects favourable conditions with a differential between the external and internal temperatures capable of cooling or
heating the environment, the recovery heat exchanger bypass is activated (bypass damper activated, rotation of the rotary exchanger
deactivated, compressor switched off) and the mixing chamber damper is opened 100%.
Activation of these functions naturally leads to the room temperature coming close to the relevant setpoint thus requiring no further
forced regulating action. The two functions are therefore completely independent.
Summer mode (free-cooling)
When the temperature rises above the regulation setpoint, thus requiring cooling, and when the conditions shown in the diagram below
apply, the recovery heat exchanger bypass is activated (bypass damper activated, rotation of the rotary exchanger deactivated,
compressor switched off).
Winter mode (free-heating)
When the temperature falls below the regulation setpoint, thus requiring heating, and when the conditions shown in the diagram below
apply, the recovery heat exchanger bypass is activated (bypass damper activated, rotation of the rotary exchanger deactivated,
compressor switched off).
9.4 Regulating the ventilation
The controller manages two fans: the supply fan and the return fan. The regulation of both fans is driven by an analogue output that
can be single (the same speed for both fans) or independent. It is also possible to configure an enabling digital output, either single or
independent. The enabling digital output is activated when the relevant analogue output is set to a value other than 0.
Both fans are regulated in the same way and the point of reference is the supply fan. It is however possible to differentiate the supply
and return fan speeds in order to balance the different losses of load in the tubes or to keep the environment at low/high pressure by
configuring parameter C35 that sets the differential between the speed of the two fans.
The return fan is switched off if the supply fan is off.
Post-ventilation can be set at a duration of C17 from when the unit is switched off to ensure the disposal and recovery of the residual
heat from the coils.
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