[derekgas]

Just for your convenience, an old (10 years plus) boiler will be around 60% efficient if you have tanks, a combi will be up to 77% efficient, a condensing boiler will be 90%+ efficient, if it is a combi, that is fine, if you have tanks then a regular condensing boiler will still be 90%+ efficient, but the system efficiency will depend on the tanks/cylinder, a standard copper cylinder will be nowhere near as efficient as a stainless steel quick recovery cylinder, these are usually well insulated and are more efficient with the timer on constant, a fully energy efficient system can save 35% of you energy bills. If you go to the trouble of installing solar panels, (which is becoming increasingly good option with another 30% hike on the way), the installation cost for solar alone can be around £3000, but grants are available, and the potential savings are growing by the month at the moment, it is now, for (in my opinion) a viable option to install solar, or ground/air source heat systems.