Index: firmware/App/Modes/ModeHeatDisinfect.c
===================================================================
diff -u -r19934ca6e36e2dcabd6a6083a9a1f15b1ed32189 -rcce2284b55a68bd4e7fc5800c54709541d440dfb
--- firmware/App/Modes/ModeHeatDisinfect.c	(.../ModeHeatDisinfect.c)	(revision 19934ca6e36e2dcabd6a6083a9a1f15b1ed32189)
+++ firmware/App/Modes/ModeHeatDisinfect.c	(.../ModeHeatDisinfect.c)	(revision cce2284b55a68bd4e7fc5800c54709541d440dfb)
@@ -1139,8 +1139,12 @@
             // at inlet temperature > 45 C
             setROPumpTargetFlowRateLPM( HEAT_DISINFECT_TARGET_RO_FLOW_TRANSFER_LPM, HEAT_DISINFECT_MAX_RO_PRESSURE_PSI );
 
-             // Set the drain pump to control mode
+            // Set the drain pump to control mode
             setDrainPumpTargetOutletPressure( HEAT_DISINFECT_TARGET_DRAIN_FILL_R2_PSI );
+
+            // Turn off trimmer heater for transition
+            stopHeater(DG_TRIMMER_HEATER);
+
             // Although there is fluid in both reservoirs, but they are set to empty
             // to begin the transition of hot water from R1 to R2.
             rsrvr2Status            = DG_RESERVOIR_BELOW_TARGET;
@@ -1203,6 +1207,10 @@
             // at inlet temperature > 45 C
             setROPumpTargetFlowRateLPM( HEAT_DISINFECT_TARGET_RO_FLOW_LPM, HEAT_DISINFECT_MAX_RO_PRESSURE_PSI );
 
+            // Start the trimmer heater since we are recirculating water and there is flow in the shunt line
+            setHeaterTargetTemperature( DG_TRIMMER_HEATER, HEAT_DISINFECT_TARGET_TEMPERATURE_C );
+            startHeater( DG_TRIMMER_HEATER );
+
             state = DG_HEAT_DISINFECT_STATE_DISINFECT_R2_TO_R1;
         }
         else if ( DG_RESERVOIR_NOT_REACHED_TARGET == rsrvr2Status )