CAV fan air volume overriden
Hi everyone,
I have set up a very simple building geometry model and HVAC as I'm trying to get to the grips with Energy Plus. Unfortunately, I have got a problem with understanding one issue, therefore I'm kindly asking for your help.
My building model is a cuboid, building envelope is adiabatic and there's not activity within the space - maximum simplification as I needed to focus on the HVAC mainly. My detailed HVAC system consists only of one constant volume fan - air flow: 12.5 m3/h, pressure rise 800 Pa, total efficiency 70%. All of the settings in the HVAC and activity tab have been set accordingly.
The problem which I encountered is that EP calculates it's own design airflow and fan power which then is taken to energy calculations, despite my user's inputs (fixed fan speed, therefore fan power should be 14.3 kW). It appears that my inputs have been overridden by EP - 1.12 kW and 0.98 m3/s
Moreover, the EP report indicates Rated Electric Power as 14.3 kW and Max Air Flow Rate 12.50 m3/s (my values - please see an attachment) and says that User-Specified values were used, although it's not truth.
Thanks for you help. Maciej
what are you trying to model? In which objects did you set your fan power and flow rates? Are the units correct - you specify 12.5 m3/s in the last paragraph, and 12.5 m3/h earlier? Which outputs are you using to see what was sized? It's possible the sizing is as you specify, but the model is ventilating per a lower outdoor air flow rate requirement.