My husband installed an English Bosch Worcester LPG boiler in our house when we were building it 8 years ago but we have always admitted that it wasn't the cleverest thing we have done. He isn't a plumber and hadn't done anything as ambitious before. In fact the place where he worked had a book running on whether the system would pass the stringient tests or not! It did take two goes to get it passed and we were very lucky to find a sympathetic maintenance company to do the annual service. Luckily (cross fingers, eyes, legs....) the boiler has been trouble free and it did save us money but we wouldn't do it again.