Index: PIControllers.c
===================================================================
diff -u -rc8d764933ccdc4a185131d77bbcc106a9223ae6b -r8d437a49a2eb86dfb38674f18a1e514998b3931f
--- PIControllers.c	(.../PIControllers.c)	(revision c8d764933ccdc4a185131d77bbcc106a9223ae6b)
+++ PIControllers.c	(.../PIControllers.c)	(revision 8d437a49a2eb86dfb38674f18a1e514998b3931f)
@@ -7,8 +7,8 @@
 *
 * @file    PIControllers.c
 *
-* @author  (last)      “rkallala”
-* @date    (last)      09-Dec-2025
+* @author  (last)      Vinayakam Mani
+* @date    (last)      14-Apr-2026
 *
 * @author  (original)  Vinayakam Mani
 * @date    (original)  07-Oct-2024
@@ -68,14 +68,15 @@
     { 0.0, 0.0, 0.90, 0.10, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 100.0, CONTROLLER_UNIDIRECTIONAL, FALSE, 0.0 },  // PI_CONTROLLER_ID_BLOOD_FLOW
 #endif
 #ifdef _DD_
-    { 0.0, 0.0, 2650, 350, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 4.0,     CONTROLLER_BIDIRECTIONAL, FALSE, 0.0 },  // PI_CONTROLLER_ID_D12_PUMP
-    { 0.0, 0.0, 2650, 350, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 4.0,     CONTROLLER_BIDIRECTIONAL, FALSE, 0.0 },  // PI_CONTROLLER_ID_D48_PUMP
-    { 0.0, 0.0, 1.0,  0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 15.0,     CONTROLLER_BIDIRECTIONAL, TRUE, 0.0 },  // PI_CONTROLLER_ID_D5_HEAT
-    { 0.0, 0.0, 1.0,  0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 5.0,     CONTROLLER_BIDIRECTIONAL, FALSE, 0.0 },  // PI_CONTROLLER_ID_D45_HEAT
-    { 0.0, 0.0, 1.0,  0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 25.0,   CONTROLLER_UNIDIRECTIONAL, FALSE, 0.0 },  // PI_CONTROLLER_ID_RO_PUMP
-    { 0.0, 0.0, 1.0,  0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.1,    CONTROLLER_UNIDIRECTIONAL, FALSE, 0.0 },  // PI_CONTROLLER_ID_RO_PUMP_MAX_PRES
-    { 0.0, 0.0, 1.0,  0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.5,    CONTROLLER_UNIDIRECTIONAL, FALSE, 0.0 },  // PI_CONTROLLER_ID_BOOST_PUMP_FLOW
-    { 0.0, 0.0, 1.0,  0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.1,    CONTROLLER_UNIDIRECTIONAL, FALSE, 0.0 },  // PI_CONTROLLER_ID_BOOST_PUMP_PRES
+    { 0.0, 0.0, 2650, 350, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 4.0,  CONTROLLER_BIDIRECTIONAL, FALSE, 0.0 },    // PI_CONTROLLER_ID_D12_PUMP
+    { 0.0, 0.0, 2650, 350, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 4.0,  CONTROLLER_BIDIRECTIONAL, FALSE, 0.0 },    // PI_CONTROLLER_ID_D48_PUMP
+    { 0.0, 0.0, 1.0,  0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 15.0, CONTROLLER_BIDIRECTIONAL, TRUE, 0.0 },     // PI_CONTROLLER_ID_D5_HEAT
+    { 0.0, 0.0, 55.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 100.0, CONTROLLER_BIDIRECTIONAL, FALSE, 0.0 },   // PI_CONTROLLER_ID_D5_HEAT_OUTER_LOOP
+    { 0.0, 0.0, 1.0,  0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 5.0,  CONTROLLER_BIDIRECTIONAL, FALSE, 0.0 },    // PI_CONTROLLER_ID_D45_HEAT
+    { 0.0, 0.0, 1.0,  0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 25.0,  CONTROLLER_UNIDIRECTIONAL, FALSE, 0.0 },  // PI_CONTROLLER_ID_RO_PUMP
+    { 0.0, 0.0, 1.0,  0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.1,  CONTROLLER_UNIDIRECTIONAL, FALSE, 0.0 },   // PI_CONTROLLER_ID_RO_PUMP_MAX_PRES
+    { 0.0, 0.0, 1.0,  0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.5,  CONTROLLER_UNIDIRECTIONAL, FALSE, 0.0 },   // PI_CONTROLLER_ID_BOOST_PUMP_FLOW
+    { 0.0, 0.0, 1.0,  0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.1,  CONTROLLER_UNIDIRECTIONAL, FALSE, 0.0 },   // PI_CONTROLLER_ID_BOOST_PUMP_PRES
     { 0.0, 0.0, 0.0,  0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 75.0,   CONTROLLER_UNIDIRECTIONAL, FALSE, 0.0 },  // PI_CONTROLLER_ID_BICARB_VOL
     { 0.0, 0.0, 0.0,  0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 1000.0,  CONTROLLER_UNIDIRECTIONAL, FALSE, 0.0 },  // PI_CONTROLLER_ID_ACID_VOL
 #endif
@@ -388,38 +389,37 @@
 
     return signals;
 }
+
 /*********************************************************************//**
  * @brief
- * The getPIControllerSignals function returns the latest requested signal sample.
+ * The setPIControllerFeedForward function sets the latest feed forward value
+ * to the corresponding PI controller.
  * @details \b Inputs: none
- * @details \b Outputs: maxErrorSumStep of controller ID
+ * @details \b Outputs: feedforward of controller ID
  * @details \b Alarms: ALARM_ID_XX_SOFTWARE_FAULT when invalid PI controller
  * Id is passed.
- * @details \b Alarms: ALARM_ID_XX_SOFTWARE_FAULT when invalid PI controller
- * stemp limit is passed.
  * @param controllerID ID filter number
- * @param stepLimit maximum step limit
- * @return latest sample requested
+ * @param feedforward calculated feed forward control value
+ * @return none
  *************************************************************************/
-void setPIControllerStepLimit( PI_CONTROLLER_ID_T controllerID, F32 stepLimit )
+void setPIControllerFeedForward( PI_CONTROLLER_ID_T controllerID, F32 feedforward )
 {
     PI_CONTROLLER_T *controller;
 
     if ( controllerID < NUM_OF_PI_CONTROLLERS_IDS )
     {
         SET_CONTROLLER( controller, controllerID );
 
-        if ( ( stepLimit > NEARLY_ZERO ) && ( stepLimit < MAX_ILIMIT ) )
+        if ( ( feedforward > controller->uMin ) && ( feedforward < controller->uMax ) )
         {
-            controller->maxErrorSumStep = stepLimit;
+            controller->feedForward = feedforward;
         }
         else
         {
 #ifdef _DD_
-            SET_ALARM_WITH_2_U32_DATA( ALARM_ID_DD_SOFTWARE_FAULT, SW_FAULT_ID_PI_CTRL_INVALID_STEP_LIMIT, (U32)stepLimit )
+            SET_ALARM_WITH_2_U32_DATA( ALARM_ID_DD_SOFTWARE_FAULT, SW_FAULT_ID_PI_CTRL_INVALID_FEED_FORWARD_LIMIT, (U32)feedforward )
 #endif
         }
-
     }
     else
     {
Index: PIControllers.h
===================================================================
diff -u -ra00631eb9cb99a828d4dc5ddf644bb7947eade0b -r8d437a49a2eb86dfb38674f18a1e514998b3931f
--- PIControllers.h	(.../PIControllers.h)	(revision a00631eb9cb99a828d4dc5ddf644bb7947eade0b)
+++ PIControllers.h	(.../PIControllers.h)	(revision 8d437a49a2eb86dfb38674f18a1e514998b3931f)
@@ -7,8 +7,8 @@
 *
 * @file    PIControllers.h
 *
-* @author  (last)      Michael Garthwaite
-* @date    (last)      11-Sep-2025
+* @author  (last)      Vinayakam Mani
+* @date    (last)      14-Apr-2026
 *
 * @author  (original)  Vinayakam Mani
 * @date    (original)  07-Oct-2024
@@ -45,6 +45,7 @@
     PI_CONTROLLER_ID_D12_PUMP,                      ///< Fresh dialysate Pump controller
     PI_CONTROLLER_ID_D48_PUMP,                      ///< Spent dialysate Pump controller
     PI_CONTROLLER_ID_D5_HEAT,                       ///< Primary heater controller
+    PI_CONTROLLER_ID_D5_HEAT_OUTER_LOOP,            ///< Primary heater controller outer loop
     PI_CONTROLLER_ID_D45_HEAT,                      ///< Trimmer heater controller
     PI_CONTROLLER_ID_RO_PUMP_FLOW,                  ///< RO Pump controller to flow
     PI_CONTROLLER_ID_RO_PUMP_PRES,                  ///< RO pump controller to maximum pressure
@@ -104,7 +105,7 @@
 void resetPIController( PI_CONTROLLER_ID_T controllerID, F32 initialControlSignal, F32 feedFowardSignal );
 F32 runPIController( PI_CONTROLLER_ID_T controllerID, F32 referenceSignal, F32 measuredSignal );
 F32 getPIControllerSignals( PI_CONTROLLER_ID_T controllerID, PI_CONTROLLER_SIGNALS_ID signalID );
-void setPIControllerStepLimit( PI_CONTROLLER_ID_T controllerID, F32 stepLimit );
+void setPIControllerFeedForward( PI_CONTROLLER_ID_T controllerID, F32 feedforward );
 
 PI_CONTROLLER_SIGNALS_DATA getDebugPIControllerSignals( PI_CONTROLLER_ID_T controllerID );