Flow overspecified at HVAC node.

[anapaulaql]

While I was working in an energy model for a two stories offices building,
when I ran the ApacheSim,I have received an error message that "flowrate over-specified at HVAC node
308/.
I will appreciate if anybody could advise on how to
rectify this...
Thanks
Ana

[Megan]

Ana,

Open up your HVAC file in ApHVAC and select the "Check network" button. This will help you find node 308. Once you find the node, check the flow controllers you have that control the flow at that node. The "flow over-specified" error is telling you that there are too many controllers defining airflow at that point.

Since node 308 is outside of a multiplex, my guess is that you have a flow controller at the system level causing this particular problem. The flow controllers in the multiplex specify the airflow in the individual zones. The sum of those airflows is the flow required at the system level. No additional flow controller is needed. If you have a flow controller at the system level, it is over-specifying the flow. Delete it and the sim should run without any errors.

Thanks,
Megan

[bootsam]

Remove one of your flow controllers. For example if you have one main branch, splitting into 4 seperate. If you have a flow control on the main, then you only need to put one on three of the branches. For some reason HVAC doesnt like it on all 4. This is how I usually do it, then it works fine.

[amirah_asilah]

Hi,

In my case, the mentioned over-specified node is only a junction between 2 FCUs which dont have any component or controller there. The FCUs serve by a PAHU, so basically the node line is only consist of airflow set at the PAHU fan. What should i do regarding this matter?

Thanks.

[farahghanem]

can you provide screenshot of your system?