Index: firmware/App/Modes/ModeHeatDisinfect.c
===================================================================
diff -u -rd32f890bb6c238c95bcaca54da79d7aa4a1898cb -r77f5c03bbc835f520b478da716d0cf5d64d9fc3e
--- firmware/App/Modes/ModeHeatDisinfect.c	(.../ModeHeatDisinfect.c)	(revision d32f890bb6c238c95bcaca54da79d7aa4a1898cb)
+++ firmware/App/Modes/ModeHeatDisinfect.c	(.../ModeHeatDisinfect.c)	(revision 77f5c03bbc835f520b478da716d0cf5d64d9fc3e)
@@ -102,6 +102,7 @@
 #define POST_HEAT_DISINFECT_WAIT_TIME_MS           ( 3 * SEC_PER_MIN * MS_PER_SECOND )                         ///< Heat disinfect final wait time before flushing the system in milliseconds.
 #define HEAT_DISINFECT_MAX_TEMP_GRADIENT_C         15.0F                                                       ///< Heat disinfect maximum allowed temperature gradient in between hottest and coldest sensors.
 #define HEAT_DISINFECT_TEMP_GRAD_OUT_RANGE_TIME_MS ( 0.16 * SEC_PER_MIN * MS_PER_SECOND )                      ///< Heat disinfect temperature gradient out of range timeout in milliseconds.
+#define HEAT_DIS_TEMP_GRAD_WAIT_2_CHECK_TIME_MS    ( 5 * SEC_PER_MIN * MS_PER_SECOND )
 #define HEAT_DISINFECT_TARGET_RO_PUMP_DC           0.4F                                                        ///< Heat disinfect target RO pump duty cycle.
 #define HEAT_DISINFECT_REF_RSRVR_TIMEOUT_MS        ( 5 * MS_PER_SECOND )                                       ///< Heat disinfect getting reference reservoirs value timeout in milliseconds.
 #define HEAT_DISINFECT_AT_82_C_TIME_MS             ( 10 * SEC_PER_MIN * MS_PER_SECOND )                        ///< Heat disinfect time at 82 C in milliseconds.
@@ -1846,7 +1847,15 @@
         }
         else if ( 0 == tempGradOutOfRangeTimer )
         {
-            tempGradOutOfRangeTimer = getMSTimerCount();
+            if ( ( TRUE == didTimeout( stateTimer, HEAT_DIS_TEMP_GRAD_WAIT_2_CHECK_TIME_MS ) ) &&
+                 ( DG_HEAT_DISINFECT_STATE_DISINFECT_R1_TO_R2 == heatDisinfectState ) )
+            {
+                tempGradOutOfRangeTimer = getMSTimerCount();
+            }
+            else if ( DG_HEAT_DISINFECT_STATE_DISINFECT_R2_TO_R1 == heatDisinfectState )
+            {
+                tempGradOutOfRangeTimer = getMSTimerCount();
+            }
         }
         else if ( TRUE == didTimeout( tempGradOutOfRangeTimer, HEAT_DISINFECT_TEMP_GRAD_OUT_RANGE_TIME_MS ) )
         {