The real life system is indeed an outdoor air system, I just thought it would make things easier as I don’t need to calculate energy demand in the system itself or anything outdoor air related. I just want to model the room temperature in the summer under these fixed conditions.
I have now used the ideal loads system with a really low cooling setpoint so that the system is always in maximum cooling mode with the desired supply temperature specified as minimum cooling temperature and the desired flow rate set as maximum cooling flow rate and limited flow rate setting.
It works but somehow this feels like a workaround (probably because it is 😄).
I was going to say ZoneVentilation:DesignFlowRate until I read "fixed supply temperature". I'm really curious what real life system do you have that provides a fixed flow + fixed temperature that isn't outdoor air?
I would say you could use an internal load, say a OtherEquipment that would represent the load by converting that fixed volume flow rate at temperature to watts (+ maybe an ElectricEquipment to model the fan portion if you want to).