Economizer changes supply air set point and zone set point temperature
Using UnitarySystem, controller:outdoorair, and setpointmanager:MixedAir to model a constant volume single zone system serving a single zone. With NoEconomizer selected the cooling coil operates to meet the loop outlet set point and the connected zone is maintained at the cooling setpoint. Enabling the economizer causes the loop outlet set point is several degrees lower and the connected zone is maintained at the heating set point. I've looked at other input decks and it seems like the setPointmanager:mixedair is set up the way others have done. Is there an obvious missing manager? How should I go about debugging this issue?
Update: The heating coil is not on. The only difference in the run input is the outdoor air controller has FixedDryBulb economizer in one case and no economizer in the other. The zone set point as reported by system node setpoint temperature is the same in both runs. A difference appears at the supply equipment outlet setpoint. In the NoEconomizer case this is set at a temperature that maintains the zone cooling setpoint, in the Economizer case it is lower and maintains the space temperature at the heating set point. If the heating set point is lowered then the economizer opens up. The input seems pretty standard and a few others have looked at it to no avail. Seems like some sort of interface issue between controller:outdoorair and unitarysystem but it could be I'm just confused by the various controllers.
Update2: Before the fans turn on, the space temperature is above the cooling set point. Once the system starts, if no economizer is present and the system is at minimum air, the DX cooling is required to maintain the cooling set point. I don't understand why a modulating economizer would force the zone temperature below not only the cooling set point but the heating set point which is 5F lower, and why it would modulate to maintain the heating set point rather than the cooling set point. In a real system, the cooling signal would drop and the economizer shut down. Why would an economizer be controlled differently from the compressor which faithfully maintains the cooling set point? Is there a control that will limit this? Sorry if this is dense, it does feel like I'm missing some basic item in the controls.
