Index: firmware/App/Controllers/DGInterface.c
===================================================================
diff -u -rc4597167d133bcafd1a0576d0f7c53f430d98d4b -r1f669c93c03ac8f246a2b791678b4b65ecb2dbd4
--- firmware/App/Controllers/DGInterface.c	(.../DGInterface.c)	(revision c4597167d133bcafd1a0576d0f7c53f430d98d4b)
+++ firmware/App/Controllers/DGInterface.c	(.../DGInterface.c)	(revision 1f669c93c03ac8f246a2b791678b4b65ecb2dbd4)
@@ -1162,16 +1162,21 @@
  *************************************************************************/
 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();
-    }
 }