I've been able to successfully generate a pressure drop report for a few systems in my project. I have an exhaust system that appears to be well-connected, but after running the pressure drop calculator have found that a negative airflow(?) has crept into the system for some reason. Why would this happen? It is a fairly simple exhaust system with two grilles, ductwork, an exhaust fan and a louver.
Thanks.
To give the community a better idea of what you are seeing, please post a stripped down sample file showing this behavior.
Perhaps you might have to check you're equipment connections and make sure they're set to bi-directional. That might fix it.