How to search/replace

I have a line that contains comma separated objects.
I want to introduce a return after every comma...
Any way to do it using search/replace

I would imagine that i could put in the replace box:

,\n

But doesn't work, even with regular expressions being on....
I've seen that I can use $1 $2... in the replace box
to replace with matchings from the search regular expression. What else can I use in the replace expression?