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 pipe for extracting fumes and supplying fresh air to the boiler).
Modern boilers are more efficient for several reasons, but their main advantage is that they are all condensing boilers. A condensing boiler has a larger 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, and even more energy is recovered from the condensing vapour.
If it is time to change your boiler, you need to decide what type of boiler is right for you. Here are some things to consider:
If you have mains gas, a gas boiler is likely to be the cheapest heating option. Our average fuel prices as of March 2019, show gas to be the cheapest heating fuel per kWh, compared to oil, economy 7, LPG and house coal.
If you don’t have a gas supply to your home, it might be worth considering a form of low carbon heating such as a heat pump or biomass. With the renewable heat incentive (RHI), these may be cheaper overall.
Alternatively you may want to get a gas connection to your home. The company that owns and operates the gas network in your area may be able to help with the cost of getting a new connection, and it may even be fully funded. Contact Energy Networks Association for further information.
Most old gas and oil boilers are regular boilers that have a separate hot water cylinder to store hot water, rather than providing it directly from the boiler. When you replace your boiler you can buy a new regular boiler, and keep your hot water cylinder, or buy a combi boiler that doesn't need a cylinder.
A regular boiler is more efficient than a combi at producing hot water in the first place, but then some heat is lost from the hot water cylinder, so a combi may be more efficient overall. Which is better for you will depend on different things:
Your hot water usage
Large families using lots of hot water are likely to be better off with a regular boiler, whereas smaller households using less may be better off with a combi boiler.
Space in your home
Combi boilers don’t need hot water cylinders, and therefore require less space in your home.
Compatibility with solar water heating
If you’re thinking of installing solar water heating, it’s worth noting that many combi boilers are not compatible with this heating system or cannot use it so effectively.
For gas and LPG boilers, the installer must be Gas Safe registered. Registered installers: Gas Safe Register
For oil boilers we would recommend that you use an OFTEC registered installer. Registered installers: OFTEC.
It’s worth getting three quotes from different installers, and you may also want to check that installers:
Your registered installer will ensure that your system complies with current building regulations, and will make sure you get all the documentation to prove this. Keep these documents safe; you will need them when you sell the property.
Learn more about the heating and hot water in your home, and how you can save more on bills.Find out more
Find out about what financial support is available in your area for home energy efficiency improvements.Read more
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