Issues with VRF Terminal Unit on AirLoopHVAC:DedicatedOutdoorAirSystem

[eringold]

Issue overview

@rraustad
I'm testing out placing a VRF Terminal unit on the OutdoorAirSystem of an AirLoopHVAC:DedicatedOutdoorAirSystem. I've created a couple test files that should be set up correctly, and seeing a couple issues:

1. If the terminal unit does not have a fan object (which should be optional when the TU is listed on the OutdoorAirSystem:EquipmentList - the fan is instead a separate component on the OASystem, and is listed on the EquipmentList), I get severe errors for missing setpoints, even though each coil has a SetpointManager on the outlet node. In this case, the TU outlet node is the same as the TU heating coil outlet node. This is 'SmallOffice_CentralDOAS_VRF_nofan_fails.idf' in the attached zip.
2. I can get a model running that has a Fan:SystemModel included in the Terminal Unit, SetpointManagers on each coil outlet (but not on the TU outlet). The error file for this model reports that Max Fan Volume Flow Rate sizes to (basically) 0. This is 'SmallOffice_CentralDOAS_VRF_working.idf' in the zip. If I only put a SPM on the TU outlet node, this will also fail with

 ** Severe  ** ZoneHVAC:TerminalUnit:VariableRefrigerantFlow: Missing temperature setpoint for TU5
 **   ~~~   ** ...use a Setpoint Manager to establish a setpoint at the TU or coil(s) outlet node."

Could you confirm that the TU will work on an AirLoopHVAC:DOAS, ideally with just a SPM on the TU outlet (OpenStudio doesn't expose the coil nodes, so needing SPMs on the coil outlets gets difficult), or that non-TU fans on the DOAS will size correctly?

EPlus Issue Files.zip

Details

Some additional details for this issue (if relevant):

• Windows 10
• Version 9.5.0-003df71316 (packaged with the OpenStudio CI build here)
  (FYI I used the v9.4.0 IDF Editor to modify the SmallOffice_CentralDOAS example file, changed the version number to 9.5 and ran using the above version from the command line)

Checklist

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• Defect file added (list location of defect file here)
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