Index: firmware/App/Modes/ModeChemicalDisinfect.c
===================================================================
diff -u -r9e5ee62245eb2a73b167eabd6c274a71a76a7b0e -r72bca5d2e489fa253f3bdfdb254261a32c7a0c19
--- firmware/App/Modes/ModeChemicalDisinfect.c	(.../ModeChemicalDisinfect.c)	(revision 9e5ee62245eb2a73b167eabd6c274a71a76a7b0e)
+++ firmware/App/Modes/ModeChemicalDisinfect.c	(.../ModeChemicalDisinfect.c)	(revision 72bca5d2e489fa253f3bdfdb254261a32c7a0c19)
@@ -25,6 +25,7 @@
 #include "MessageSupport.h"
 #include "ModeChemicalDisinfect.h"
 #include "ModeFault.h"
+#include "ModeHeatDisinfect.h"
 #include "ModeStandby.h"
 #include "NVDataMgmt.h"
 #include "OperationModes.h"
@@ -178,6 +179,10 @@
 static DISINFECT_NV_OPS_T disinfectNVOps;                                                                      ///< Disinfect non-volatile memory operations.
 static BOOL haveDrainParamsBeenInit[ NUM_OF_DG_RESERVOIRS ];                                                   ///< Boolean flag to indicate whether the drain parameters have been reset or not.
 
+#ifndef _RELEASE_
+static NELSON_SUPPORT_T nelsonSupport;                                                                         ///< Nelson support.
+#endif
+
 // ********** private function prototypes **********
 
 static DG_CHEM_DISINFECT_STATE_T handleChemicalDisinfectStartState( void );
@@ -207,6 +212,10 @@
 static void monitorModeChemicalDisinfect( void );
 static void writeDisinfectDataToNV( DG_USAGE_INFO_ITEMS_T info );
 
+#ifndef _RELEASE_
+static void setNelsonSupportConditions( void );
+#endif
+
 /*********************************************************************//**
  * @brief
  * The initChemicalDisinfectMode function initializes the chemical
@@ -268,6 +277,12 @@
     R2FullVolume                               = 0.0F;
     disinfectantMixRatio                       = 0.0F;
 
+#ifndef _RELEASE_
+    nelsonSupport                              = NELSON_NONE;
+
+    setNelsonSupportConditions();
+#endif
+
     initPersistentAlarm( ALARM_ID_DG_CHEM_DISINFECT_TARGET_TEMP_OUT_OF_RANGE, DISINFECT_TEMP_OUT_OF_RANGE_TIMEOUT_MS, DISINFECT_TEMP_OUT_OF_RANGE_TIMEOUT_MS );
     initPersistentAlarm( ALARM_ID_DG_CHEM_DISINFECT_TARGET_COND_OUT_OF_RANGE, DISINFECT_COND_OUT_OF_RANGE_TIMEOUT_MS, DISINFECT_COND_OUT_OF_RANGE_TIMEOUT_MS );
 }
@@ -289,7 +304,12 @@
 
     setCPLDCleanLEDColor( CPLD_CLEAN_LED_YELLOW );
 
-    activateAlarmNoData( ALARM_ID_DG_CHEM_DISINFECT_INSERT_ACID );
+#ifndef _RELEASE_
+    if ( nelsonSupport != NELSON_POS_CONTROL_CHEM_DISINFECT )
+#endif
+    {
+        activateAlarmNoData( ALARM_ID_DG_CHEM_DISINFECT_INSERT_ACID );
+    }
 
     return chemDisinfectState;
 }
@@ -726,7 +746,8 @@
     handleDisinfectantMixing( getMeasuredFlowRateLPM( RO_FLOW_SENSOR ) * ML_PER_LITER, disinfectantMixRatio );
 
 #ifndef _RELEASE_
-    if ( getSoftwareConfigStatus( SW_CONFIG_DISABLE_DISINFECT_CONDUCTIVITY_CHECK ) != SW_CONFIG_ENABLE_VALUE )
+    if ( ( getSoftwareConfigStatus( SW_CONFIG_DISABLE_DISINFECT_CONDUCTIVITY_CHECK ) != SW_CONFIG_ENABLE_VALUE ) ||
+         ( nelsonSupport != NELSON_POS_CONTROL_CHEM_DISINFECT ) )
 #endif
     {
         if ( cd2Conductivity < MIN_PRIME_ACID_CONDUCTIVITY_US_PER_CM )
@@ -1061,6 +1082,14 @@
             chemDisinfectUIState = CHEM_DISINFECT_UI_STATE_FLUSH_AFTER_DISINFECT;
             stateTimer           = getMSTimerCount();
             state                = DG_CHEM_DISINFECT_STATE_DRAIN_R1;
+
+#ifndef _RELEASE_
+            if ( ( NELSON_POS_CONTROL_CHEM_DISINFECT == nelsonSupport ) || ( NELSON_CHEM_DISINFECT == nelsonSupport ) )
+            {
+                deenergizeActuators( NO_PARK_CONC_PUMPS );
+                state = DG_CHEM_DISINFECT_STATE_COMPLETE;
+            }
+#endif
         }
         else
         {
@@ -1238,7 +1267,17 @@
 
     chemDisinfectUIState = CHEM_DISINFECT_UI_STATE_COMPLETE;
 
-    requestNewOperationMode( DG_MODE_CHFL );
+#ifndef _RELEASE_
+    if ( nelsonSupport != NELSON_NONE )
+    {
+        nelsonSupport = NELSON_NONE;
+        requestNewOperationMode( DG_MODE_STAN );
+    }
+    else
+#endif
+    {
+        requestNewOperationMode( DG_MODE_CHFL );
+    }
 
     return state;
 }
@@ -1259,6 +1298,11 @@
     {
         SET_ALARM_WITH_1_U32_DATA( alarmDetectedPendingTrigger, prevChemDisinfectState )
     }
+
+#ifndef _RELEASE_
+   nelsonSupport = NELSON_NONE;
+#endif
+
     requestNewOperationMode( DG_MODE_FAUL );
 }
 
@@ -1558,6 +1602,7 @@
         data.overallElapsedTime = calcTimeSince( overallChemDisinfectTimer );
         data.stateElapsedTime   = calcTimeSince( stateTimer );
         data.cancellationMode   = (U32)cancellationMode;
+        data.nelsonSupportMode  = (U32)nelsonSupport;
 
         //If the mode is in the actual chemical disinfect states, publish the elapsed time, otherwise publish 0 to avoid confusion
         if ( chemDisinfectState > DG_CHEM_DISINFECT_STATE_FLUSH_DRAIN  )
@@ -1569,9 +1614,9 @@
         }
         else
         {
-            uiData.chemDisinfectCountdownTime = 0.0;
-            data.R1FillLevel                  = 0.0;
-            data.R2FillLevel                  = 0.0;
+            uiData.chemDisinfectCountdownTime = 0.0F;
+            data.R1FillLevel                  = 0.0F;
+            data.R2FillLevel                  = 0.0F;
         }
 
         data.chemDisinfectUIState             = chemDisinfectUIState;
@@ -1696,4 +1741,58 @@
     }
 }
 
+// ********** Nelson Support Functions **********
+
+#ifndef _RELEASE_
+/*********************************************************************//**
+ * @brief
+ * The setNelsonSupportConditions function sets the disinfect variables for
+ * Nelson support.
+ * @details Inputs: nelsonSupport
+ * @details Outputs: chemDisinfectState, flushCircWaitTime, stateTimer
+ * @return: none
+ *************************************************************************/
+static void setNelsonSupportConditions( void )
+{
+    F32 temperature = 0.0F;
+
+    switch ( nelsonSupport )
+    {
+        case NELSON_POS_CONTROL_CHEM_DISINFECT:
+        case NELSON_CHEM_DISINFECT:
+            // The target temperature is set to low so the heater will turn on but it will not heat because
+            // we are very close to the target. Set the stop temperature to a temperature lower by a couple degrees
+            // make sure the timer will continuously count against the disinfection time to inoculate.
+            // NOTE: this is not part of the commercial code so no #defines
+            temperature = 20.0F;
+
+            // Set the valves to start flush circulation
+            setValveState( VPI, VALVE_STATE_CLOSED );
+            setValveState( VBF, VALVE_STATE_CLOSED );
+            setValveState( VPD, VALVE_STATE_OPEN_C_TO_NC );
+            setValveState( VDR, VALVE_STATE_DRAIN_C_TO_NO );
+            setValveState( VRC, VALVE_STATE_DRAIN_C_TO_NO );
+            setValveState( VPO, VALVE_STATE_NOFILL_C_TO_NO );
+            setValveState( VRF, VALVE_STATE_R2_C_TO_NO );
+            setValveState( VRO, VALVE_STATE_R1_C_TO_NO );
+            setValveState( VRI, VALVE_STATE_R1_C_TO_NO );
+            setValveState( VRD1, VALVE_STATE_CLOSED );
+            setValveState( VRD2, VALVE_STATE_CLOSED );
+            setROPumpTargetFlowRateLPM( RO_PUMP_TARGET_FLUSH_FLOW_RATE_LPM, MAX_RO_PUMP_FLUSH_FILL_PRESSURE_PSI );
+            setHeaterTargetTemperature( DG_PRIMARY_HEATER, temperature );
+            startHeater( DG_PRIMARY_HEATER );
+            turnOnUVReactor( INLET_UV_REACTOR );
+            turnOnUVReactor( OUTLET_UV_REACTOR );
+            flushCircWaitTime  = FLUSH_CICRCULATION_INITIAL_WAIT_TIME_MS;
+            stateTimer         = getMSTimerCount();
+            chemDisinfectState = DG_CHEM_DISINFECT_STATE_FLUSH_CIRCULATION;
+            break;
+
+        case NELSON_NONE:
+        default:
+            break;
+    }
+}
+#endif
+
 /**@}*/