Index: firmware/App/Modes/ModeHeatDisinfect.c
===================================================================
diff -u -rec9448b37fef681607e8b3ab0020cf7a41454295 -rf5d8da2ffed2cb22132c791039ba8a1221e31223
--- firmware/App/Modes/ModeHeatDisinfect.c	(.../ModeHeatDisinfect.c)	(revision ec9448b37fef681607e8b3ab0020cf7a41454295)
+++ firmware/App/Modes/ModeHeatDisinfect.c	(.../ModeHeatDisinfect.c)	(revision f5d8da2ffed2cb22132c791039ba8a1221e31223)
@@ -118,8 +118,8 @@
 #define MIX_DRAIN_TEMPERATURE_THRESHOLD_C          60.0F                                                       ///< Temperature threshold for performing mix drain or normal drain.
 
 // Passive cool defines
-#define PASSIVE_COOL_TIME_TO_DRAIN_MS            ( 20 * MS_PER_SECOND )                                        ///< Passive cool time needed to be below temperature range in milliseconds.
-#define PASSIVE_COOL_TEMP_THRESHOLD_TO_DRAIN_C   59.0F                                                         ///< Passive cool threshold temperature to drain in C.
+#define PASSIVE_COOL_TIME_TO_DRAIN_MS             ( 20 * MS_PER_SECOND )                                        ///< Passive cool time needed to be below temperature range in milliseconds.
+#define PASSIVE_COOL_TEMP_THRESHOLD_TO_DRAIN_C    59.0F                                                         ///< Passive cool threshold temperature to drain in C.
 
 #ifndef _RELEASE_
 #define NELSON_SUPPORT_TARGET_TEMP_C               6.0F                                                        // Nelson support heat disinfect target temperature in C.
@@ -1429,7 +1429,7 @@
         F32 TDiC = getTemperatureValue( TEMPSENSORS_INLET_DIALYSATE );
         F32 THdC = getTemperatureValue( TEMPSENSORS_HEAT_DISINFECT );
 
-        if ( ( TDiC > PASSIVE_COOL_TEMP_THRESHOLD_TO_DRAIN_C ) && ( THdC > PASSIVE_COOL_TEMP_THRESHOLD_TO_DRAIN_C ) )
+        if ( ( TDiC > PASSIVE_COOL_TEMP_THRESHOLD_TO_DRAIN_C ) || ( THdC > PASSIVE_COOL_TEMP_THRESHOLD_TO_DRAIN_C ) )
         {
             passiveCoolHeatDisStatus.tempsCheckStartTimeMS = getMSTimerCount();
         }