Index: firmware/App/Services/SystemCommMessages.c
===================================================================
diff -u -re608f0a2bda2ad8df59a604a511cbd2a1c323dc3 -r3850bef541c43c1fb81663eb7d1ca6c98e933627
--- firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision e608f0a2bda2ad8df59a604a511cbd2a1c323dc3)
+++ firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision 3850bef541c43c1fb81663eb7d1ca6c98e933627)
@@ -4330,19 +4330,21 @@
     // verify payload length
     if ( sizeof( U32 ) == message->hdr.payloadLen )
     {
+        NELSON_SUPPORT_T nelson;
+
         memcpy( &payload, message->payload, sizeof( U32 ) );
 
-        NELSON_SUPPORT_T nelson = (NELSON_SUPPORT_T)payload;
+        nelson = (NELSON_SUPPORT_T)payload;
 
         switch( nelson )
         {
             case NELSON_INOCULATE:
-                setNelsonSupportMode( nelson );
+                setHeatNelsonSupportMode( nelson );
                 requestNewOperationMode( DG_MODE_HEAT );
                 break;
 
             case NELSON_HEAT_DISINFECT:
-                setNelsonSupportMode( nelson );
+                setHeatNelsonSupportMode( nelson );
                 requestNewOperationMode( DG_MODE_HEAT );
                 break;
 
@@ -4351,13 +4353,17 @@
                 requestNewOperationMode( DG_MODE_CHEM );
                 break;
 
+            case NELSON_POS_CONTROL_HEAT_DISINFECT:
+                setHeatNelsonSupportMode( nelson );
+                requestNewOperationMode( DG_MODE_HEAT );
+
             case NELSON_CHEM_DISINFECT:
                 setChemNelsonSupportMode( nelson );
                 requestNewOperationMode( DG_MODE_CHEM );
                 break;
 
             case NELSON_DRAIN_SAMPLES:
-                setNelsonSupportMode( nelson );
+                setHeatNelsonSupportMode( nelson );
                 requestNewOperationMode( DG_MODE_HEAT );
                 break;
         }