This question already has an answer here:
I have noticed that when you are exchanging comments with someone under an answer, and reach a certain number of comments, you are opted to start a chat instead. Is it possible to initiate this right away? If not, could you make it possible?
My example of when this could be nice to have is this: I wrote a general answer to a question about Hibernate, and after some time someone asked a quite specific question in a comment underneath my answer. I would like to help out, but still it would be nice not to clutter my general answer with very specific comments. In this case I would have liked to just initiate a chat with the person asking right away, and then avoid a long comment conversation that really is quite irrelevant to the actual answer.