A better way to say thanks than to create a reply is to click the heart 
at the bottom of a reply. This tells the person that you liked the reply without requiring the person to read another post.It also shows others that
- the reply is useful
- this person is giving useful information. Hearts are like the currency of Discourse forums. While you can’t actually spend them they do count toward maintaining trust level 3 , so please consider clicking a heart when giving thanks.
Excerpt from here.