@Todd K., your hunch is correct (i.e. "imports with some warnings about not everything being imported (probably key to this problem)". What OpenStudio does forward-translate to EnergyPlus, it does very well. Yet not so much when it comes to HVAC/plant when (reverse-translatingreverse-translation an IDF. ). From IDF to OSM, one is going from a finer (lower-level) model to a slightly more abstract (higher-level) one; information will undoubtedly be lost in translation. You'll find UMH posts on this, like this one. And a note in the SDK documentation (last paragraph).