Andrea Rossi has responded on his Journal of Nuclear Physics Site to a question asking about his manufacturing facilities and a request for pictures of them:
Our factories are in the USA. We have a R&D center in Italy wherein we also manufacture prototypes. We are programming a manufacturing center in Sweden. All the other information are confidential, let alone the photos.
There’s not a whole lot to go on there, of course, but I think it is probably safe to say that if Rossi now has a partner in the United States who is already a manufacturing company (as AR says), that the E-Cats will be manufactured in its factories.