I've been using the Eco-King C100 combi boiler for a couple of years now. It has been a very reliable source of heat and hot water for me. I live in a very small house and do not have room for a water softener so my initial concern was how to prevent mineralization that could build up inside my boiler. I opted for an electronic device that has a current going through two wires wrapped around the water line that goes into the boiler and is supposed to magically align molecules thus preventing mineralization inside the boiler. So far so good. I like the videos that are made on YouTube with Chad, he is very thorough and explains things well.