diff --git a/src/EnergyPlus/RoomAirModelManager.cc b/src/EnergyPlus/RoomAirModelManager.cc
index fd89474081d..da3cae900e5 100644
--- a/src/EnergyPlus/RoomAirModelManager.cc
+++ b/src/EnergyPlus/RoomAirModelManager.cc
@@ -2741,12 +2741,14 @@ namespace RoomAir {
             ReturnNodeNum = OutdoorAirUnit::GetOutdoorAirUnitReturnAirNode(state, EquipIndex);
         } break;
         case DataZoneEquipment::ZoneEquipType::PackagedTerminalAirConditioner: { // ZoneHVAC : PackagedTerminalAirConditioner
-            SupplyNodeNum = state.dataUnitarySystems->unitarySys[EquipIndex - 1].getAirOutNode(state, EquipName, 0, errorfound);
-            ReturnNodeNum = state.dataUnitarySystems->unitarySys[EquipIndex - 1].getAirInNode(state, EquipName, 0, errorfound);
+            EquipIndex = UnitarySystems::getIndex(state, EquipName, zoneEquipType, errorfound);
+            SupplyNodeNum = state.dataUnitarySystems->unitarySys[EquipIndex].AirOutNode;
+            ReturnNodeNum = state.dataUnitarySystems->unitarySys[EquipIndex].AirInNode;
         } break;
         case DataZoneEquipment::ZoneEquipType::PackagedTerminalHeatPump: { // ZoneHVAC : PackagedTerminalHeatPump
-            SupplyNodeNum = state.dataUnitarySystems->unitarySys[EquipIndex - 1].getAirOutNode(state, EquipName, 0, errorfound);
-            ReturnNodeNum = state.dataUnitarySystems->unitarySys[EquipIndex - 1].getAirInNode(state, EquipName, 0, errorfound);
+            EquipIndex = UnitarySystems::getIndex(state, EquipName, zoneEquipType, errorfound);
+            SupplyNodeNum = state.dataUnitarySystems->unitarySys[EquipIndex].AirOutNode;
+            ReturnNodeNum = state.dataUnitarySystems->unitarySys[EquipIndex].AirInNode;
         } break;
         case DataZoneEquipment::ZoneEquipType::UnitHeater: { // ZoneHVAC : UnitHeater
             ReturnNodeNum = UnitHeater::GetUnitHeaterAirInletNode(state, EquipIndex);
@@ -2761,8 +2763,9 @@ namespace RoomAir {
             SupplyNodeNum = VentilatedSlab::GetVentilatedSlabZoneAirInNode(state, EquipIndex);
         } break;
         case DataZoneEquipment::ZoneEquipType::PackagedTerminalHeatPumpWaterToAir: { // ZoneHVAC : WaterToAirHeatPump
-            SupplyNodeNum = state.dataUnitarySystems->unitarySys[EquipIndex - 1].getAirOutNode(state, EquipName, 0, errorfound);
-            ReturnNodeNum = state.dataUnitarySystems->unitarySys[EquipIndex - 1].getAirInNode(state, EquipName, 0, errorfound);
+            EquipIndex = UnitarySystems::getIndex(state, EquipName, zoneEquipType, errorfound);
+            SupplyNodeNum = state.dataUnitarySystems->unitarySys[EquipIndex].AirOutNode;
+            ReturnNodeNum = state.dataUnitarySystems->unitarySys[EquipIndex].AirInNode;
         } break;
         case DataZoneEquipment::ZoneEquipType::WindowAirConditioner: { // ZoneHVAC : WindowAirConditioner
             ReturnNodeNum = WindowAC::GetWindowACReturnAirNode(state, EquipIndex);
diff --git a/src/EnergyPlus/UnitarySystem.cc b/src/EnergyPlus/UnitarySystem.cc
index 4cfd27cdd93..e4ee05808fa 100644
--- a/src/EnergyPlus/UnitarySystem.cc
+++ b/src/EnergyPlus/UnitarySystem.cc
@@ -16581,6 +16581,25 @@ namespace UnitarySystems {
         return airNode;
     }
 
+    int
+    getIndex(EnergyPlusData &state, std::string const &UnitarySysName, DataZoneEquipment::ZoneEquipType zoneEquipType, bool &errFlag)
+    {
+
+        int EquipIndex = 0;
+        for (int UnitarySysNum = 0; UnitarySysNum < state.dataUnitarySystems->numUnitarySystems; ++UnitarySysNum) {
+            if (Util::SameString(UnitarySysName, state.dataUnitarySystems->unitarySys[UnitarySysNum].Name)) {
+                if (zoneEquipType == DataZoneEquipment::ZoneEquipType::PackagedTerminalAirConditioner ||
+                    zoneEquipType == DataZoneEquipment::ZoneEquipType::PackagedTerminalHeatPump ||
+                    zoneEquipType == DataZoneEquipment::ZoneEquipType::PackagedTerminalHeatPumpWaterToAir) {
+                    EquipIndex = UnitarySysNum;
+                    break;
+                }
+            }
+        }
+        if (EquipIndex < 0) errFlag = true;
+        return EquipIndex;
+    }
+
     int UnitarySys::getAirOutNode(EnergyPlusData &state, std::string_view UnitarySysName, int const ZoneOAUnitNum, bool &errFlag)
     {
         if (state.dataUnitarySystems->getInputOnceFlag) {
diff --git a/src/EnergyPlus/UnitarySystem.hh b/src/EnergyPlus/UnitarySystem.hh
index c3e906298f6..d602f20dc2e 100644
--- a/src/EnergyPlus/UnitarySystem.hh
+++ b/src/EnergyPlus/UnitarySystem.hh
@@ -966,6 +966,8 @@ namespace UnitarySystems {
     void setupAllOutputVars(EnergyPlusData &state, int const numAllSystemTypes);
     void isWaterCoilHeatRecoveryType(EnergyPlusData const &state, int const waterCoilNodeNum, bool &nodeNotFound);
 
+    int getIndex(EnergyPlusData &state, std::string const &UnitarySysName, DataZoneEquipment::ZoneEquipType zoneEquipType, bool &errFlag);
+
 } // namespace UnitarySystems
 struct UnitarySystemsData : BaseGlobalStruct
 {