fix: address misc hvac_library.osm issues

[Ski90Moo]

Summary

• Fix autosize resistive defrost heater capacity in hvac_library.osm (Closes hvac_Library.osm object OS:AirConditioner:VariableRefrigerantFlow Defrost wattage should be autosize #770)
• Rename mislabeled gas/electric unitary system; add genuine VRF-free multispeed DX heat pump (Closes The Default HVAC Library object "MultiSpeed Heat Pump AirToAir" is not a Heat Pump #834)
• Add 2-speed DX cycling unitary system with CoolReheat dehumidification mode to HVAC library (Closes Add unitary system with dehumidification (2-speed DX, CoolReheat) to default HVAC library #887)

Changes

All changes are in src/openstudio_app/Resources/default/hvac_library.osm:

• Closes hvac_Library.osm object OS:AirConditioner:VariableRefrigerantFlow Defrost wattage should be autosize #770 (434fd01a): Set resistive defrost heater capacity to autosize so it is properly sized during simulation.
• Closes The Default HVAC Library object "MultiSpeed Heat Pump AirToAir" is not a Heat Pump #834 (129f4770): Corrected the name of a mislabeled unitary system entry; added a genuine VRF-free multispeed DX heat pump entry.
• Closes Add unitary system with dehumidification (2-speed DX, CoolReheat) to default HVAC library #887 (bf96e804): Added OS:AirLoopHVAC:UnitarySystem configured for 2-speed DX cooling with CoolReheat dehumidification control, reusing existing shared objects (fan, heating coil, cooling coil, supplemental coil, availability schedule) already present in the library.

Test plan

• Open the default HVAC library in OpenStudio Application and confirm all three new/modified entries appear in the HVAC Components panel
• Drag the 2-speed DX dehumidification unitary system onto an air loop and confirm it loads without errors
• Verify the defrost heater capacity field is autosize for the affected coil
• Confirm no regressions in other library entries

🤖 Generated with Claude Code

[Ski90Moo]

Test Results

All tests completed against hvac_library.osm loaded in OpenStudio 3.11.0.

MCP / Programmatic Inspection

Test	Result
All changed/added entries present in library (14 AirLoopHVACUnitarySystem objects)	✅
Unitary - 2-Speed DX Elec heat - Cycling - Dehumidify present with correct handle	✅
Resistive defrost heater capacity = autosize at all 6 affected locations	✅
CoilCoolingDXTwoStageWithHumidityControlMode referenced by new unitary system resolves correctly	✅
New unitary system key fields: CoolReheat, BlowThrough, LatentOrSensibleLoadControl, SupplyAirFlowRate	✅
All UUID references (fan, coils, supplemental coil, schedule) accepted on model load — no errors	✅

Manual GUI

Test	Result
Unitary - 2-Speed DX Elec heat - Cycling - Dehumidify drags onto air loop without errors	✅

EnergyPlus Simulations (via MCP)

Two annual simulations were run using the MCP server (OpenStudio 3.11.0 / EnergyPlus 24.x).

Simulation 1 — PSZ-HP, Denver CO (CZ 5B)
Exercises: defrost heater autosize fix (commit 434fd01a) and DX heat pump entries (commit 129f4770)

Metric	Value
Status	✅ Success — no fatal or severe errors
EUI	44.5 kBtu/ft²
Total site energy	202 GJ
Unmet heating hours	16.5
Unmet cooling hours	0

Simulation 2 — 2-speed DX + CoolReheat, Houston TX (CZ 2A)
Exercises: new dehumidification unitary system (commit bf96e804)

Metric	Value
Status	✅ Success — no fatal or severe errors
EUI	29.5 kBtu/ft²
Total site energy	134 GJ
Unmet heating hours	10.7
Unmet cooling hours	0.3

Houston (CZ 2A — hot-humid) was chosen to exercise the CoolReheat dehumidification path during the annual run.

Note on CoolReheat + Humidistat

EnergyPlus requires a ZoneControl:Humidistat object (with both humidifying and dehumidifying setpoint schedules) in the controlling zone whenever DehumidificationControlType = CoolReheat is active. This is a building model requirement, not a library object requirement — the humidistat is placed in the zone, not in the HVAC component. Users dragging Unitary - 2-Speed DX Elec heat - Cycling - Dehumidify from the library will need to add a humidistat to their thermal zone before simulating.