Index: firmware/App/Controllers/DGInterface.c
===================================================================
diff -u -r1cfa9cbcd9ae84a8df767c7777ff3beca067aaa8 -r914d62486ceca1eaa9ea68dd30f64082d5e12500
--- firmware/App/Controllers/DGInterface.c	(.../DGInterface.c)	(revision 1cfa9cbcd9ae84a8df767c7777ff3beca067aaa8)
+++ firmware/App/Controllers/DGInterface.c	(.../DGInterface.c)	(revision 914d62486ceca1eaa9ea68dd30f64082d5e12500)
@@ -1163,16 +1163,21 @@
  *************************************************************************/
 static void checkDGTrimmerHeaterStatus( void )
 {
-    U32 trimmerState = dgHeatersData.trimmerHeaterState;
+    U32 trimmerState  = dgHeatersData.trimmerHeaterState;
+    DG_OP_MODE_T dgOp = getDGOpMode();
 
-    if ( ( TRUE == dgTrimmerHeaterOn ) && ( HEATER_EXEC_STATE_OFF == trimmerState ) )
+    if ( ( dgOp != DG_MODE_HEAT ) && ( dgOp != DG_MODE_CHEM ) )
     {
-        cmdStartDGTrimmerHeater();
+        // In heat disinfect and chemical disinfect, the trimmer heater is controlled by the DG itself so no commands from HD should be sent.
+        if ( ( TRUE == dgTrimmerHeaterOn ) && ( HEATER_EXEC_STATE_OFF == trimmerState ) )
+        {
+            cmdStartDGTrimmerHeater();
+        }
+        else if ( ( FALSE == dgTrimmerHeaterOn ) && ( trimmerState != HEATER_EXEC_STATE_OFF ) )
+        {
+            cmdStopDGTrimmerHeater();
+        }
     }
-    else if ( ( FALSE == dgTrimmerHeaterOn ) && ( trimmerState != HEATER_EXEC_STATE_OFF ) )
-    {
-        cmdStopDGTrimmerHeater();
-    }
 }