Index: firmware/App/Modes/Prime.c
===================================================================
diff -u -r173e5908bada098006b85c1267147a187d2eaef4 -r7de21ac8b699cafdfeaefbf2c062c3e21bcc956d
--- firmware/App/Modes/Prime.c	(.../Prime.c)	(revision 173e5908bada098006b85c1267147a187d2eaef4)
+++ firmware/App/Modes/Prime.c	(.../Prime.c)	(revision 7de21ac8b699cafdfeaefbf2c062c3e21bcc956d)
@@ -7,8 +7,8 @@
 *
 * @file    Prime.c
 *
-* @author  (last)      Dara Navaei
-* @date    (last)      17-Oct-2022
+* @author  (last)      Michael Garthwaite
+* @date    (last)      21-Oct-2022
 *
 * @author  (original)  Quang Nguyen
 * @date    (original)  08-Dec-2020
@@ -36,7 +36,7 @@
 
 // ********** private definitions **********
 
-#define MAX_PRIME_TIME                                      ( 15 * SEC_PER_MIN )                               ///< Maximum prime time (in seconds).
+#define MAX_PRIME_TIME                                      ( 30 * SEC_PER_MIN )                               ///< Maximum prime time (in seconds).
 #define PRIME_DATA_PUB_INTERVAL                             ( MS_PER_SECOND / TASK_GENERAL_INTERVAL )          ///< Interval (ms/task time) at which the prime data is published on the CAN bus.
 
 #define BLOOD_PUMP_FAST_FLOW_RATE_PURGE_AIR_ML_MIN          300                                                ///< Blood pump fast flow rate to fill fluid.
@@ -416,7 +416,7 @@
  * @brief
  * The purgeAirValvesBloodPumpControl function controls valves and blood pump
  * to purge air.
- * @details Inputs: none
+ * @details Inputs: primeFirstPurgePass
  * @details Outputs: run blood pump, close VDI, VDO, VBA and VBV valves, open VBT valve
  * @return current state (sub-mode)
  *************************************************************************/
@@ -500,8 +500,9 @@
  * @brief
  * The handlePrimePurgeAirState function checks for air trap level and moves
  * to blood circuit circulation state if fluid is detected at upper sensor.
- * @details Inputs: air trap levels
- * @details Outputs: runs blood pump, control valves to trap air
+ * @details Inputs: air trap levels, primeFirstPurgePass, purgeAirTimeOutStartTime
+ * @details Outputs: runs blood pump, control valves to trap air, primeFirstPurgePass
+ * noAirDetectedStartTime
  * @return current state
  *************************************************************************/
 static HD_PRE_TREATMENT_PRIME_STATE_T handlePrimePurgeAirState( void )
@@ -513,18 +514,6 @@
         SET_ALARM_WITH_1_U32_DATA( ALARM_ID_HD_PRIME_SALINE_PURGE_AIR_TIME_OUT, PURGE_AIR_TIME_OUT_COUNT );
     }
 
-    if ( AIR_TRAP_LEVEL_FLUID == getAirTrapLevel( AIR_TRAP_LEVEL_SENSOR_LOWER ) )
-    {
-        if ( FALSE == primeFirstPurgePass )
-        {
-            setBloodPumpTargetFlowRate( BLOOD_PUMP_FAST_FLOW_RATE_PURGE_AIR_ML_MIN, MOTOR_DIR_FORWARD, PUMP_CONTROL_MODE_OPEN_LOOP );
-        }
-        else
-        {
-            setBloodPumpTargetFlowRate( BLOOD_PUMP_SLOW_FLOW_RATE_PURGE_AIR_ML_MIN, MOTOR_DIR_FORWARD, PUMP_CONTROL_MODE_OPEN_LOOP );
-        }
-    }
-
     if ( AIR_TRAP_LEVEL_FLUID == getAirTrapLevel( AIR_TRAP_LEVEL_SENSOR_UPPER ) )
     {
         setValvePosition( VDI, VALVE_POSITION_C_CLOSE );
@@ -533,15 +522,11 @@
         setValvePosition( VBV, VALVE_POSITION_B_OPEN );
         setValveAirTrap( STATE_CLOSED );
 
+        setBloodPumpTargetFlowRate( BLOOD_PUMP_FAST_FLOW_RATE_CIRC_BLOOD_CIRCUIT_ML_MIN, MOTOR_DIR_FORWARD, PUMP_CONTROL_MODE_OPEN_LOOP );
 
-        if ( FALSE == primeFirstPurgePass )
-        {
-            setBloodPumpTargetFlowRate( BLOOD_PUMP_FAST_FLOW_RATE_CIRC_BLOOD_CIRCUIT_ML_MIN, MOTOR_DIR_FORWARD, PUMP_CONTROL_MODE_OPEN_LOOP );
-        }
-        else
-        {
-            setBloodPumpTargetFlowRate( BLOOD_PUMP_SLOW_FLOW_RATE_CIRC_BLOOD_CIRCUIT_ML_MIN, MOTOR_DIR_FORWARD, PUMP_CONTROL_MODE_OPEN_LOOP );
-        }
+        // Once the dialyzer is no longer dry from the first pass of purge air, we can set flow to the fast rate
+        // until we are in a new priming state.
+        primeFirstPurgePass = FALSE;
         noAirDetectedStartTime = getMSTimerCount();
         state = HD_PRIME_SALINE_CIRC_BLOOD_CIRCUIT_STATE;
     }
@@ -572,12 +557,7 @@
     {
         purgeAirValvesBloodPumpControl();
         purgeAirTimeOutStartTime = getMSTimerCount();
-        if ( TRUE == primeFirstPurgePass )
-        {
-            primeFirstPurgePass = FALSE;
-        }
         state = HD_PRIME_SALINE_PURGE_AIR_STATE;
-
     }
 
     if ( TRUE == didTimeout( noAirDetectedStartTime, NO_AIR_DETECTED_COUNT ) )
@@ -609,8 +589,13 @@
 
     if ( TRUE == getReservoirFillStatus( DG_RESERVOIR_1 ) )
     {
-        cmdSetDGActiveReservoir( DG_RESERVOIR_1 );
+        DG_SWITCH_RSRVRS_CMD_T rsrvrCmd;
 
+        rsrvrCmd.reservoirID            = (U32)DG_RESERVOIR_1;
+        rsrvrCmd.useLastTrimmerHeaterDC = FALSE;
+
+        cmdSetDGActiveReservoir( &rsrvrCmd );
+
         if ( TRUE == hasDGCompletedReservoirSwitch() )
         {
             U32 dialyzerDialysateVolume = getDialyzerDialysateVolume();
@@ -761,7 +746,7 @@
     {
         state = HD_PRIME_RESERVOIR_TWO_FILL_COMPLETE_STATE;
     }
-
+    // TODO: Rework alarm and timeout logic here. PRIME_SALINE_DIALYZER_TIME_OUT_COUNT may not be reached.
     if ( TRUE == didTimeout( primeSalineDialyzerStartTime, PRIME_SALINE_DIALYZER_TIME_OUT_COUNT ) )
     {
         SET_ALARM_WITH_1_U32_DATA( ALARM_ID_PRIME_SALINE_DIALYZER_TIME_OUT, PRIME_SALINE_DIALYZER_TIME_OUT_COUNT );  // Trigger HD prime saline dialyzer time out alarm.
@@ -790,8 +775,13 @@
 
     if ( TRUE == getReservoirFillStatus( DG_RESERVOIR_2 ) )
     {
-        cmdSetDGActiveReservoir( DG_RESERVOIR_2 );
+        DG_SWITCH_RSRVRS_CMD_T rsrvrCmd;
 
+        rsrvrCmd.reservoirID            = (U32)DG_RESERVOIR_1;
+        rsrvrCmd.useLastTrimmerHeaterDC = FALSE;
+
+        cmdSetDGActiveReservoir( &rsrvrCmd );
+
         if ( TRUE == hasDGCompletedReservoirSwitch() )
         {
             signalBloodPumpHardStop();