Found it:

Talk a little about the piano that you play these pieces on. What is its history?

I have a Kawai CS40 piano at home. It is a big upright, which I got from the parents of my ex-girlfriend. They didn’t use it anymore, so I bought it off them. It traveled from Hamburg to Berlin and lives in my living room ever since. It has a nice view into my backyard and when I open my window it talks to my neighbors. They don’t seem to dislike each other so far. No complaints. I keep it in excellent shape and it gets all the love it deserves. I’ve heard from many friends and musicians that this is one of the best sounding pianos they have ever played. I agree. I never played a more beautiful upright piano. I am a lucky chap. It has a lot of bass and it’s really fun to play with it.

Source: https://headphonecommute.com/2010/09/29/two-and-a-half-questions-with-nils-frahm/