I have lived in my townhouse for five years (bought it new), and have a tankless water heater. My husband noticed water on the floor in the basement, and of course it turns out that the heat exchanger had gone bad. I’ve never been told that I needed to flush it out, and it was corroded and had sprung a leak and needed to be replaced. Darien Romero was our tech, and was super pleasant, professional, and knowledgeable. When the part came in, Darien brought another tech with him who was also great. I’m sorry I can’t remember his name, but it started with a J. Anyway, very pleased with the service I received from Cooper, plumbing and heating, and will definitely use you again in the future.