Index: firmware/App/Modes/ModeFill.c
===================================================================
diff -u -r1d444d78857351aa7bb094e9574b0a4aa2051102 -r6190a4ad94521b74164f1e1fbd79ed359c7c27fb
--- firmware/App/Modes/ModeFill.c	(.../ModeFill.c)	(revision 1d444d78857351aa7bb094e9574b0a4aa2051102)
+++ firmware/App/Modes/ModeFill.c	(.../ModeFill.c)	(revision 6190a4ad94521b74164f1e1fbd79ed359c7c27fb)
@@ -20,7 +20,6 @@
 #include "FPGA.h"
 #include "Heaters.h"
 #include "LoadCell.h"
-#include "ModeFault.h"
 #include "ModeFill.h"
 #include "OperationModes.h"
 #include "PersistentAlarm.h"
@@ -128,8 +127,11 @@
     turnOnUVReactor( INLET_UV_REACTOR );
     turnOnUVReactor( OUTLET_UV_REACTOR );
 
-    startPrimaryHeater();
+    // NOTE: The target flow rate should be set prior to setting the start primary heater
+    // because the initial guess in the heaters driver needs the target flow to calculate
+    // the new PWMs for the main and small primary heaters
     setROPumpTargetFlowRate( TARGET_RO_FLOW_RATE_L, TARGET_RO_PRESSURE_PSI );
+    startPrimaryHeater();
 }
 
 /*********************************************************************//**