In very simple terms, say you spend £2000 fitting a new, efficient (and complicated) boiler, to save maybe £200 per year on gas costs. At the end of 10 years you'll balance the books but only if you have no breakdown costs in that time. In the meantime your old cast iron job that's been running happily for the last 35+ years could still be going strong (apart from the odd thermocouple). OK it maybe isn't eco-friendly or "green" but ........
