Index: firmware/App/Controllers/Heaters.c
===================================================================
diff -u -r5109bb981cab2025fcb9de33e303d046085efa18 -rb909022e776df298f2fdad4f944afae29ad2d396
--- firmware/App/Controllers/Heaters.c	(.../Heaters.c)	(revision 5109bb981cab2025fcb9de33e303d046085efa18)
+++ firmware/App/Controllers/Heaters.c	(.../Heaters.c)	(revision b909022e776df298f2fdad4f944afae29ad2d396)
@@ -99,6 +99,7 @@
     U32 controlIntervalCounter;                                                                                                    ///< Heater control interval counter.
     BOOL isThisFirstControl;                                                                                                       ///< Heater is this first control interval.
     BOOL useLastDutyCycle;                                                                                                         ///< Heater has use previous duty cycle been requested flag.
+    F32 prevDiaTargetFlowLPM;                                                                                                      ///< Heater previous target dialysate flow in L/min.
 } HEATER_STATUS_T;
 
 static HEATER_STATUS_T heatersStatus[ NUM_OF_DG_HEATERS ];                                                                         ///< Heaters status.
@@ -156,6 +157,7 @@
         heatersStatus[ heater ].controlIntervalCounter = 0;
         heatersStatus[ heater ].isThisFirstControl     = TRUE;
         heatersStatus[ heater ].useLastDutyCycle       = FALSE;
+        heatersStatus[ heater ].prevDiaTargetFlowLPM   = 0.0F;
     }
 
     // Initialize the persistent alarms
@@ -717,12 +719,14 @@
     HEATERS_STATE_T state = HEATER_EXEC_STATE_TRIMMER_CONTROL_TO_TARGET;
     F32 tempDutyCycle     = 0.0F;
     DG_HEATERS_T heater   = DG_TRIMMER_HEATER;
+    F32 targetFlowLPM     = getTargetDialysateFlowLPM();
     U32 controlInterval   = ( TRUE == heatersStatus[ heater ].isThisFirstControl ? TRIMMER_HEATER_INITIAL_CONTROL_INTERVAL_COUNT :
                                                                                    TRIMMER_HEATER_CONTROL_INTERVAL_COUNT );
 
-    // If the inactive reservoir has changed from the last run transition to ramp state to recalculate the
+    // If the inactive reservoir has changed from the last run or the target dialysate flow has changed, transition to ramp state to recalculate the
     // duty cycle for the next delivery
-    if ( heatersStatus[ heater ].inactiveRsrvr != getInactiveReservoir() )
+    if ( ( heatersStatus[ heater ].inactiveRsrvr != getInactiveReservoir() ) ||
+         ( fabs( heatersStatus[ heater ].prevDiaTargetFlowLPM - targetFlowLPM ) > NEARLY_ZERO ) )
     {
         state = HEATER_EXEC_STATE_TRIMMER_RAMP_TO_TARGET;
     }
@@ -736,7 +740,6 @@
         // dialysate inlet temperature sensor is used rather than the theoretical calculations.
         F32 dialysateInletTemperature = getTemperatureValue( TEMPSENSORS_OUTLET_REDUNDANT );
         F32 targetTemperature         = heatersStatus[ heater ].targetTempC;
-        F32 targetFlowLPM             = getTargetDialysateFlowLPM();
         F32 dutyCycle                 = calculateTrimmerHeaterDutyCycle( targetTemperature, dialysateInletTemperature, targetFlowLPM, TRUE );
 
         tempDutyCycle = heatersStatus[ heater ].dutyCycle.data + dutyCycle;
@@ -746,6 +749,8 @@
         setHeaterDutyCycle( heater );
     }
 
+    heatersStatus[ heater ].prevDiaTargetFlowLPM = targetFlowLPM;
+
     return state;
 }
 
Index: firmware/App/Services/Reservoirs.c
===================================================================
diff -u -r5109bb981cab2025fcb9de33e303d046085efa18 -rb909022e776df298f2fdad4f944afae29ad2d396
--- firmware/App/Services/Reservoirs.c	(.../Reservoirs.c)	(revision 5109bb981cab2025fcb9de33e303d046085efa18)
+++ firmware/App/Services/Reservoirs.c	(.../Reservoirs.c)	(revision b909022e776df298f2fdad4f944afae29ad2d396)
@@ -170,6 +170,9 @@
         getNVRecord2Driver( GET_CAL_FILL_CONDUCTIVITIES_RECORD, (U08*)&fillCondCalRecord, sizeof( fillCondCalRecord ), 0, ALARM_ID_NO_ALARM );
     }
 
+    // Constantly update the trimmer heater target temperature
+    setHeaterTargetTemperature( DG_TRIMMER_HEATER, getTrimmerHeaterTargetTemperature() );
+
     // If the mode is fault or it is standby and the RO volume has not been written already, write it
     if ( ( ( DG_MODE_FAUL == getCurrentOperationMode() ) || ( DG_MODE_STAN == getCurrentOperationMode() ) ) && ( FALSE == nvOps.hasROGenVolBeenWrittenToNV ) )
     {
@@ -711,7 +714,7 @@
             heatersTempCalc.timeUFDecayMS        = (F32)heatersTempCalc.timeReservoirCycleMS - heatersTempCalc.timeReservoirFillMS;
             UFTimeConstant                       = heatersTempCalc.timeUFDecayMS * UFTauCPerMS;
             heatersTempCalc.tempUFFill           = tempLastFill + UFTimeConstant;
-
+            // TODO If tempUFFill < 25 make it 25 C or apply exponential Tau
             tempTargetNumerator                  = heatersTempCalc.tempReservoir0 - ( ( heatingConstsCalRecord.ultrafilterVolmL / targetFillVolML ) * heatersTempCalc.tempUFFill );
             tempTargetDenominator                = ( ( targetFillVolML - heatingConstsCalRecord.ultrafilterVolmL ) / targetFillVolML );
             tempTargetC                          = tempTargetNumerator / tempTargetDenominator;