Index: firmware/App/Controllers/Heaters.c
===================================================================
diff -u -r18a20aa5b66f0b6123f066ce2c79b9fb056a0469 -r4b25bf00656b9067a13541014fa1333386a7ed95
--- firmware/App/Controllers/Heaters.c	(.../Heaters.c)	(revision 18a20aa5b66f0b6123f066ce2c79b9fb056a0469)
+++ firmware/App/Controllers/Heaters.c	(.../Heaters.c)	(revision 4b25bf00656b9067a13541014fa1333386a7ed95)
@@ -348,19 +348,19 @@
 
             if ( DG_PRIMARY_HEATER == heater )
             {
-                alarm    = ALARM_ID_RO_FLOW_TOO_LOW_WHILE_PRIMARY_HEATER_IS_ON;
-                measFlow = getMeasuredFlowRateLPM( RO_FLOW_SENSOR );
-                minFlow  = MIN_RO_HEATER_FLOWRATE_LPM;
+                alarm     = ALARM_ID_RO_FLOW_TOO_LOW_WHILE_PRIMARY_HEATER_IS_ON;
+                measFlow  = getMeasuredFlowRateLPM( RO_FLOW_SENSOR );
+                minFlow   = MIN_RO_HEATER_FLOWRATE_LPM;
+                isFlowLow = ( measFlow < minFlow ? TRUE : FALSE );
             }
             else
             {
-                alarm    = ALARM_ID_DIALYSATE_FLOW_TOO_LOW_WHILE_TRIMMER_HEATER_IS_ON;
-                measFlow = getMeasuredFlowRateLPM( DIALYSATE_FLOW_SENSOR );
-                minFlow  = MIN_DIALYSATE_FLOWRATE_LPM;
+                alarm     = ALARM_ID_DIALYSATE_FLOW_TOO_LOW_WHILE_TRIMMER_HEATER_IS_ON;
+                measFlow  = getMeasuredRawFlowRateLPM( DIALYSATE_FLOW_SENSOR );
+                minFlow   = MIN_DIALYSATE_FLOWRATE_LPM;
+                isFlowLow = ( measFlow - minFlow < NEARLY_ZERO ? TRUE : FALSE );
             }
 
-            isFlowLow = ( measFlow < minFlow ? TRUE : FALSE );
-
             checkPersistentAlarm( alarm, isFlowLow, measFlow, minFlow );
         }
         else