IES-VE User Forum

I have been trying to setup a schematic in ApacheHVAC that incorporates CO2 readings that modulate the outside air damper. I have gotten the schematic to run without using any control on the outside air damper (other than setting an independent time switch that determines the mixed air temperature), but whenever I try to proportionally control the amount of OA, it gives me errors everytime. I have had similar issues when trying to modulate the economizer mode based on enthalpy. The two errors that I get from all of the different schematics are:

- Flow Over-specified at node x. This error always will appear at the end of the entire schematic.

- I also get errors stating that the OA damper is under-specified. I have set the schematic up with a dependent sensors that cover both if the CO2 is above and below 900ppm.

Basically, I wanted to see if there is some information that I could get to help me use these controllers, and if there are other items that I need to consider when trying to proportionally control the outside air damper.

Thanks.

I'm not too hot on Apache-Hvac but I've had this before.

Over-specified
Do you have a flow controller on both the inlet and outlet? If so remove the outlet flow controller.

Under-specified
I think this means that the apache engine doesn't have enough information to calculate the flow in the branch containing the damper. Have you checked to see if you have a negative flow?

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