Replacing an old gas boiler with an A-rated high-efficiency condensing boiler and improving your heating controls will significantly cut your home's carbon dioxide emissions - and could save you as much as €200-€500 a year. The costs for replacing a boiler will vary, but a straightforward gas boiler replacement will typically cost around €1600.00 - €2000.00
Modern boilers are more efficient for several reasons, but their main advantage is that they are all condensing boilers. All well-maintained boilers burn their fuel very efficiently, but they inevitably lose some heat in the hot gases that escape up the flue. A condensing boiler has a bigger heat exchanger, so it recovers more heat, sends cooler gases up the flue and is more efficient. Sometimes the flue gases get so cool that the water vapour in the gas condenses out (hence the name). When this happens, even more energy is recovered from the condensing vapour, and the efficiency gets higher still.