Just in case someone finds it useful: my complete Ventilation menu. For my heatpump the airflow range is 70-300 m3/h, you may need to adjust those values to match your model.
define Fan.Active dummy
attr Fan.Active devStateIcon 0:vent_ventilation_level_0 1:vent_ventilation_level_1 2:vent_ventilation_level_2 3:vent_ventilation_level_3
attr Fan.Active fm_type smarttogglebutton
attr Fan.Active group THZ-Fans
attr Fan.Active room Ventilation
attr Fan.Active setList 0 1 2 3
attr Fan.Active webCmd 0:1:2:3
define Notify_p07FanStageDay notify Fan.Active set Mythz p07FanStageDay $EVENT
define Notify_FanselectorDay notify (Mythz.p07FanStageDay.*) setstate Fan.Active $EVTPART1
define Fan.Idle dummy
attr Fan.Idle devStateIcon 0:vent_ventilation_level_0 1:vent_ventilation_level_1 2:vent_ventilation_level_2 3:vent_ventilation_level_3
attr Fan.Idle group THZ-Fans
attr Fan.Idle room Ventilation
attr Fan.Idle setList 0 1 2 3
attr Fan.Idle webCmd 0:1:2:3
define Notify_p08FanStageNight notify Fan.Idle set Mythz p08FanStageNight $EVENT
define Notify_FanselectorNight notify (Mythz.p08FanStageNight.*) setstate Fan.Idle $EVTPART1
define Fan.Unscheduled dummy
attr Fan.Unscheduled alias Start Unscheduled Ventilation
attr Fan.Unscheduled devStateIcon 0:vent_ventilation_level_0 1:vent_ventilation_level_1 2:vent_ventilation_level_2 3:vent_ventilation_level_3
attr Fan.Unscheduled group THZ-FansUnscheduled
attr Fan.Unscheduled room Ventilation
attr Fan.Unscheduled setList 0 1 2 3
attr Fan.Unscheduled webCmd 0:1:2:3
define Notify_p99startUnschedVent notify Fan.Unscheduled set Mythz p99startUnschedVent $EVENT
define Notify_UnschedVent notify (Mythz.p99startUnschedVent.*) setstate Fan.Unscheduled $EVTPART1
define Fan.PassCool dummy
attr Fan.PassCool devStateIcon 0:vent_ventilation_level_0 1:vent_ventilation_level_1 2:vent_ventilation_level_2
attr Fan.PassCool group THZ-Fans
attr Fan.PassCool room Ventilation
attr Fan.PassCool setList 0 1 2
attr Fan.PassCool webCmd 0:1:2
define Notify_p75passiveCooling notify Fan.PassCool set Mythz p75passiveCooling $EVENT
define Notify_PassiveCooling notify (Mythz.p75passiveCooling.*) setstate Fan.PassCool $EVTPART1
define Fan.Stage.0 dummy
attr Fan.Stage.0 group THZ-FansUnscheduledDuration
attr Fan.Stage.0 alias Stage 0 [mins]
attr Fan.Stage.0 room Ventilation
attr Fan.Stage.0 setList state:slider,0,5,480
attr Fan.Stage.0 webCmd state
define Notify_p46UnschedVent0 notify Fan.Stage.0 set Mythz p46UnschedVent0 $EVENT
define Notify_Fan.Stage.0 notify (Mythz.p46UnschedVent0.*) setstate Fan.Stage.0 $EVTPART1
define Fan.Stage.1 dummy
attr Fan.Stage.1 group THZ-FansUnscheduledDuration
attr Fan.Stage.1 room Ventilation
attr Fan.Stage.1 alias Stage 1 [mins]
attr Fan.Stage.1 setList state:slider,0,5,480
attr Fan.Stage.1 webCmd state
define Notify_p45UnschedVent1 notify Fan.Stage.1 set Mythz p45UnschedVent1 $EVENT
define Notify_Fan.Stage.1 notify (Mythz.p45UnschedVent1.*) setstate Fan.Stage.1 $EVTPART1
define Fan.Stage.2 dummy
attr Fan.Stage.2 group THZ-FansUnscheduledDuration
attr Fan.Stage.2 room Ventilation
attr Fan.Stage.2 alias Stage 2 [mins]
attr Fan.Stage.2 setList state:slider,0,5,480
attr Fan.Stage.2 webCmd state
define Notify_p44UnschedVent2 notify Fan.Stage.2 set Mythz p44UnschedVent2 $EVENT
define Notify_Fan.Stage.2 notify (Mythz.p44UnschedVent2.*) setstate Fan.Stage.2 $EVTPART1
define Fan.Stage.3 dummy
attr Fan.Stage.3 group THZ-FansUnscheduledDuration
attr Fan.Stage.3 room Ventilation
attr Fan.Stage.3 alias Stage 3 [mins]
attr Fan.Stage.3 setList state:slider,0,5,480
attr Fan.Stage.3 webCmd state
define Notify_p43UnschedVent3 notify Fan.Stage.3 set Mythz p43UnschedVent3 $EVENT
define Notify_Fan.Stage.3 notify (Mythz.p43UnschedVent3.*) setstate Fan.Stage.3 $EVTPART1
define Fan.AirIn.Stage.1 dummy
attr Fan.AirIn.Stage.1 group THZ-Fans_Airflow_Stage.1
attr Fan.AirIn.Stage.1 room Ventilation
attr Fan.AirIn.Stage.1 alias Air Input [m3/h]
attr Fan.AirIn.Stage.1 setList state:slider,70,1,300
attr Fan.AirIn.Stage.1 webCmd state
define Notify_p37Fanstage1AirflowInlet notify Fan.AirIn.Stage.1 set Mythz p37Fanstage1AirflowInlet $EVENT
define Notify_Fan.AirIn.Stage.1 notify (Mythz.p37Fanstage1AirflowInlet.*) setstate Fan.AirIn.Stage.1 $EVTPART1
define Fan.AirOut.Stage.1 dummy
attr Fan.AirOut.Stage.1 group THZ-Fans_Airflow_Stage.1
attr Fan.AirOut.Stage.1 room Ventilation
attr Fan.AirOut.Stage.1 alias Air Output [m3/h]
attr Fan.AirOut.Stage.1 setList state:slider,70,1,300
attr Fan.AirOut.Stage.1 webCmd state
define Notify_p40Fanstage1AirflowOutlet notify Fan.AirOut.Stage.1 set Mythz p40Fanstage1AirflowOutlet $EVENT
define Notify_Fan.AirOut.Stage.1 notify (Mythz.p40Fanstage1AirflowOutlet.*) setstate Fan.AirOut.Stage.1 $EVTPART1
define Fan.AirIn.Stage.2 dummy
attr Fan.AirIn.Stage.2 group THZ-Fans_Airflow_Stage.2
attr Fan.AirIn.Stage.2 room Ventilation
attr Fan.AirIn.Stage.2 alias Air Input [m3/h]
attr Fan.AirIn.Stage.2 setList state:slider,70,1,300
attr Fan.AirIn.Stage.2 webCmd state
define Notify_p38Fanstage2AirflowInlet notify Fan.AirIn.Stage.2 set Mythz p38Fanstage2AirflowInlet $EVENT
define Notify_Fan.AirIn.Stage.2 notify (Mythz.p38Fanstage2AirflowInlet.*) setstate Fan.AirIn.Stage.2 $EVTPART1
define Fan.AirOut.Stage.2 dummy
attr Fan.AirOut.Stage.2 group THZ-Fans_Airflow_Stage.2
attr Fan.AirOut.Stage.2 room Ventilation
attr Fan.AirOut.Stage.2 alias Air Output [m3/h]
attr Fan.AirOut.Stage.2 setList state:slider,70,1,300
attr Fan.AirOut.Stage.2 webCmd state
define Notify_p41Fanstage2AirflowOutlet notify Fan.AirOut.Stage.2 set Mythz p41Fanstage2AirflowOutlet $EVENT
define Notify_Fan.AirOut.Stage.2 notify (Mythz.p41Fanstage2AirflowOutlet.*) setstate Fan.AirOut.Stage.2 $EVTPART1
define Fan.AirIn.Stage.3 dummy
attr Fan.AirIn.Stage.3 group THZ-Fans_Airflow_Stage.3
attr Fan.AirIn.Stage.3 room Ventilation
attr Fan.AirIn.Stage.3 alias Air Input [m3/h]
attr Fan.AirIn.Stage.3 setList state:slider,70,1,300
attr Fan.AirIn.Stage.3 webCmd state
define Notify_p39Fanstage3AirflowInlet notify Fan.AirIn.Stage.3 set Mythz p39Fanstage3AirflowInlet $EVENT
define Notify_Fan.AirIn.Stage.3 notify (Mythz.p39Fanstage3AirflowInlet.*) setstate Fan.AirIn.Stage.3 $EVTPART1
define Fan.AirOut.Stage.3 dummy
attr Fan.AirOut.Stage.3 group THZ-Fans_Airflow_Stage.3
attr Fan.AirOut.Stage.3 room Ventilation
attr Fan.AirOut.Stage.3 alias Air Output [m3/h]
attr Fan.AirOut.Stage.3 setList state:slider,70,1,300
attr Fan.AirOut.Stage.3 webCmd state
define Notify_p42Fanstage3AirflowOutlet notify Fan.AirOut.Stage.3 set Mythz p42Fanstage3AirflowOutlet $EVENT
define Notify_Fan.AirOut.Stage.3 notify (Mythz.p42Fanstage3AirflowOutlet.*) setstate Fan.AirOut.Stage.3 $EVTPART1
#define Fan.InputPower dummy
#attr Fan.InputPower setList 0 1 2 3
#attr Fan.InputPower group THZ-Fans
#attr Fan.InputPower devStateIcon 0:vent_ventilation_level_0 1:vent_ventilation_level_1 2:vent_ventilation_level_2 3:vent_ventilation_level_3