Built-In Air-Cooled Chiller Curve Incorrect
At some point in recent versions, an air-cooled chiller object was built into the HVAC library. The issue is, one of the curves that's attached to that chiller causes the energy usage of the chiller to increase as the load on the chiller decreases. Seems like someone must have just grabbed the wrong curve when making that change.
I don't think it's important specifically what curve is used, but the curve should at least be representative of the general behavior of a chiller. I'm attaching a chart comparing the value of this curve to a couple of other standard curves. The curve in question is the Energy Input Ratio as a function of part-load ratio, which determines the fraction of rated energy use the chiller will use at a given part-load operating point.