Calculating the enthalpy means to calculate the energy content of the air, taking into consideration both the temperature and the air humidity. The value is given in energy per kilogram of air (kJ/kg). Enthalpy is calculated for both outdoor air and room air.


e.g.

Outdoor air (T=17oC / RH=70%) has an enthalpy of 38.63 kJ/kg

Room air (T=19oC / RH=40%) has an enthalpy of 33.70 kJ/kg

In case of cooling demand it is more energy efficient to recirculate the room air, as it requires less energy for cooling, even though dry bulb temperature of it is higher.



The function has to be activated for "Damper" type sequence if it is intended for control of the enthalpy.


The function is not active when using free cooling, in which case the outdoor air is used for cooling the room instead.


Enthalpy control requires four sensors:

  • Outdoor temperature sensor / Intake temperature sensor
  • Outdoor humidity sensor
  • Room / Extract air temperature sensor
  • Room humidity sensor


Cooling recovery mode must also be active.


Activation of the enthalpy control for the recirculation sequence



Variable

Available options & Selection

Note


Activate Humidity control

Configuration > Functions > Function activation > Heating/Cooling sequence setup > Recirculation 1

Enable enthalpy control

| No | Yes |



Activate cooling recovery mode

Configuration > Functions > Temperature control

Cooling recovery mode

| Off | On |


Temperature difference to start cooling recovery

[0.0] oC



Temperature and humidity sensors

Configuration > I/O allocation settings > Analog inputs

Outdoor/Intake temperature

Any available I/O


Extract air/Room temperature

Humidity room/extract air

Humidity outdoor



Related topics:

Psychrometric chart (external link)

Cooling recovery mode

Mixing damper function