Index: firmware/App/Modes/ModeHeatDisinfect.c
===================================================================
diff -u -r6703d916afad5bfc0f5282e8ff6a09d8ce6d9180 -r28e9d54e3e8b43589cc06c33a563cb6fec8c576f
--- firmware/App/Modes/ModeHeatDisinfect.c	(.../ModeHeatDisinfect.c)	(revision 6703d916afad5bfc0f5282e8ff6a09d8ce6d9180)
+++ firmware/App/Modes/ModeHeatDisinfect.c	(.../ModeHeatDisinfect.c)	(revision 28e9d54e3e8b43589cc06c33a563cb6fec8c576f)
@@ -74,7 +74,7 @@
 #define BICARB_PUMP_SPEED_ML_PER_MIN               -30.0F                                                      ///< Bicarb concentrate pump speed in mL/min.
 
 // Flush and drain R1 and R2
-#define RSRVRS_FULL_VOL_ML                         1900.0F                                                     ///< Reservoirs 1 & 2 full volume in mL.
+#define RSRVRS_FULL_VOL_ML                         1850.0F                                                     ///< Reservoirs 1 & 2 full volume in mL.
 #define RSRVRS_PARTIAL_FILL_VOL_ML                 500.0F                                                      ///< Reservoirs 1 & 2 partial volume in mL.
 #define RSRVRS_FULL_STABLE_TIME_COUNT              ( ( 4 * MS_PER_SECOND ) / TASK_GENERAL_INTERVAL )           ///< Reservoirs 1 & 2 full stable time in counts.
 #define RSRVRS_FILL_UP_TIMEOUT_MS                  ( 5 * SEC_PER_MIN * MS_PER_SECOND )                         ///< Reservoirs 1 & 2 full fill up timeout in ms.
@@ -107,6 +107,7 @@
 #define HEAT_DISINFECT_AT_82_C_TIME_MS             ( 10 * SEC_PER_MIN * MS_PER_SECOND )                        ///< Heat disinfect time at 82 C in milliseconds.
 #define HEAT_DISINFECT_AT_77_C_TIME_MS             ( 32 * SEC_PER_MIN * MS_PER_SECOND )                        ///< Heat disinfect time at 77 C in milliseconds.
 #define HEAT_DISNFECT_MIN_OVERRIDE_TIME            ( SEC_PER_MIN * MS_PER_SECOND )                             ///< Heat disinfect minimum override time.
+#define HEAT_DISINFECT_PREP_FOR_TRANSFER_TIME_MS   ( 30 * MS_PER_SECOND )                                      ///< Heat disinfect prepare for transfer hot water time in milliseconds.
 
 // Mix drain R1 and R2
 #define RSRVRS_MIX_DRAIN_TIMEOUT_MS                ( 5 * SEC_PER_MIN * MS_PER_SECOND )                         ///< Reservoirs 1 & 2 mix drain timeout in ms.
@@ -212,6 +213,7 @@
 static DG_HEAT_DISINFECT_STATE_T handleHeatDisinfectFlushDrainR1State( void );
 static DG_HEAT_DISINFECT_STATE_T handleHeatDisinfectFillWithWaterState( void );
 static DG_HEAT_DISINFECT_STATE_T handleHeatDisinfectDisinfectR1ToR2State( void );
+static DG_HEAT_DISINFECT_STATE_T handleHeatDisinfectPrepareForHotWaterTransitionState( void );
 static DG_HEAT_DISINFECT_STATE_T handleHeatDisinfectFillR2WithHotWaterState( void );
 static DG_HEAT_DISINFECT_STATE_T handleHeatDisinfectDisinfectR2ToR1State( void );
 static DG_HEAT_DISINFECT_STATE_T handleHeatDisinfectCoolDownHeatersState( void );
@@ -332,6 +334,28 @@
 
 /*********************************************************************//**
  * @brief
+ * The isHeatDisinfectInTransitionHotWater function returns the status of
+ * heat disinfect that whether it is in transition hot water water mode or
+ * not
+ * @details Inputs: heatDisinfectState
+ * @details Outputs: none
+ * @return TRUE if the mode is transfer hot water mode otherwise, FALSE
+ *************************************************************************/
+BOOL isHeatDisinfectInTransitionHotWater( void )
+{
+    BOOL status = FALSE;
+
+    if ( ( DG_HEAT_DISINFECT_STATE_PREPARE_FOR_HOT_WATER_TRANSITION == heatDisinfectState ) ||
+         ( DG_HEAT_DISINFECT_STATE_FILL_R2_WITH_HOT_WATER == heatDisinfectState ) )
+    {
+        status = TRUE;
+    }
+
+    return status;
+}
+
+/*********************************************************************//**
+ * @brief
  * The execHeatDisinfectMode function executes the heat disinfect mode
  * state machine.
  * @details Inputs: heatDisinfectState
@@ -399,6 +423,10 @@
             heatDisinfectState = handleHeatDisinfectDisinfectR1ToR2State();
             break;
 
+        case DG_HEAT_DISINFECT_STATE_PREPARE_FOR_HOT_WATER_TRANSITION:
+            heatDisinfectState = handleHeatDisinfectPrepareForHotWaterTransitionState();
+            break;
+
         case DG_HEAT_DISINFECT_STATE_FILL_R2_WITH_HOT_WATER:
             heatDisinfectState = handleHeatDisinfectFillR2WithHotWaterState();
             break;
@@ -1127,15 +1155,6 @@
         case HEAT_DISINFECT_COMPLETE:
             requestConcentratePumpOff( CONCENTRATEPUMPS_CP1_ACID, NO_PARK_CONC_PUMPS );
             requestConcentratePumpOff( CONCENTRATEPUMPS_CP2_BICARB, NO_PARK_CONC_PUMPS );
-            // Set the valves to transfer hot water from R1 to R2 and fill up R2.
-            setValveState( VRO, VALVE_STATE_R2_C_TO_NC );
-            setValveState( VRD1, VALVE_STATE_OPEN );
-            setValveState( VRD2, VALVE_STATE_CLOSED );
-            setValveState( VRI, VALVE_STATE_R1_C_TO_NO );
-            setValveState( VRF, VALVE_STATE_R2_C_TO_NO );
-            setDrainPumpTargetOutletFlowLPM( HEAT_DISINFECT_TARGET_RO_FLOW_TRANSFER_LPM );
-            // Turn off trimmer heater for transition
-            stopHeater( DG_TRIMMER_HEATER );
 
             // Although there is fluid in both reservoirs, but they are set to empty
             // to begin the transition of hot water from R1 to R2.
@@ -1145,7 +1164,7 @@
             rsrvr1RefVolML                          = 0.0F;
             rsrvr2RefVolML                          = 0.0F;
             tempGradOutOfRangeTimer                 = 0;
-            state                                   = DG_HEAT_DISINFECT_STATE_FILL_R2_WITH_HOT_WATER;
+            state                                   = DG_HEAT_DISINFECT_STATE_PREPARE_FOR_HOT_WATER_TRANSITION;
             timeStatus[ RSRVR_AT_77_C ].startTimeMS = 0;
             timeStatus[ RSRVR_AT_82_C ].startTimeMS = 0;
             break;
@@ -1161,6 +1180,39 @@
 
 /*********************************************************************//**
  * @brief
+ * The handleHeatDisinfectPrepareForHotWaterTransitionState function handles
+ * the heat disinfect prepare for hot water state. In this state, the fluid is
+ * run a certain period of time with the heaters are at a much lower duty cycle
+ * and then the actuators are set to transition the hot water to reservoir 2.
+ * @details Inputs: stateTimer
+ * @details Outputs: stateTimer
+ * @return next state of the heat disinfect state machine
+ *************************************************************************/
+static DG_HEAT_DISINFECT_STATE_T handleHeatDisinfectPrepareForHotWaterTransitionState( void )
+{
+    DG_HEAT_DISINFECT_STATE_T state = DG_HEAT_DISINFECT_STATE_PREPARE_FOR_HOT_WATER_TRANSITION;
+
+    if ( TRUE == didTimeout( stateTimer, HEAT_DISINFECT_PREP_FOR_TRANSFER_TIME_MS ) )
+    {
+        // Set the valves to transfer hot water from R1 to R2 and fill up R2.
+        setValveState( VRO, VALVE_STATE_R2_C_TO_NC );
+        setValveState( VRD1, VALVE_STATE_OPEN );
+        setValveState( VRD2, VALVE_STATE_CLOSED );
+        setValveState( VRI, VALVE_STATE_R1_C_TO_NO );
+        setValveState( VRF, VALVE_STATE_R2_C_TO_NO );
+        setDrainPumpTargetOutletFlowLPM( HEAT_DISINFECT_TARGET_RO_FLOW_TRANSFER_LPM );
+        // Turn off trimmer heater for transition
+        stopHeater( DG_TRIMMER_HEATER );
+
+        stateTimer = getMSTimerCount();
+        state      = DG_HEAT_DISINFECT_STATE_FILL_R2_WITH_HOT_WATER;
+    }
+
+    return state;
+}
+
+/*********************************************************************//**
+ * @brief
  * The handleHeatDisinfectFillR2WithHotWaterState function handles fill R2
  * with water state. The state transfers hot water from reservoir 1 to
  * reservoir 2 until hot water overflows from reservoir 2 to reservoir 1.