IES-VE User Forum

I have a problem running macroflow. I am simulating an officebuilding with a mechanical ventilation system modulated in ApacheHVAC. The occupants of the building have the possibility to open the windows when temperatures are high, so I modulated in macroflow that windows are opened when temperatures exceeds 26 degree celcius (Ta>26 in timeprofile).
When running this simulation with both the macroflo and ApacheHVAC-box ticked i get the error-message:
"Error in MacroFlo. Maximum pressure exceeded in room STN_0214. Likely cause: air being supplied/extracted when openings are closed."
But when doing the exact same simulation just with the windows closed at all times in MacroFlo, there is no problems simulating.

What can cause the problem?

Hi Andy

That's an odd one since it is normally having windows closed which causes that particular error.

My only thought is that the HVAC network is a red herring and the whole problem is actually being caused by the window openings. Does the model run with the windows opening but the HVAC network disconnected? If it still comes up with the same error it could be that you have some very thin thermal zones with large openings which can sometimes create pressure errors.

Otherwise I am at a bit of a loss without being able to examine the model directly.

CP