Replace boiler with new condensing boiler

Priority for Completion: Medium

This recommendation is triggered if the property has an old inefficient boiler. The exact benefit will depend upon a wide range of factors including the age and model of the boiler being replaced, the model of the new boiler, the cost of the fuel and the occupancy of the home. Generally, the more the heating system is used and the older the boiler being replaced, the bigger the savings will be. However, boilers should always be professionally installed and may require a significant financial investment so we have rated this recommendation as being medium priority. It is usually worth completing if it can be afforded and if the boiler being replaced is over ten years old.

Condensing boilers are modern highly efficient boilers. The Energy Saving Trust estimate replacing an old G-rated non-condensing boiler with a new condensing boiler could save you as much as £310 a year. You must also ensure that appropriate controls are installed to meet the current Building Regulations.

How do condensing boilers work?

Almost all new boilers are condensing. You are probably wondering what is special about a condensing boiler. You may also be wondering what is different between condensing boilers and older non-condensing boilers.

Condensing boilers are high-efficiency boilers. They are a good choice if you are looking for a greener and more efficient boiler. They should also be cheaper to run as you will use less fuel.

Condensing boilers are able to make better use of the heat they generate from burning fuels. It doesn't matter what sort of fuel you are burning (whether its is gas, oil or even biomass). In a non-condensing heat-only boiler, some heat is wasted in the form of hot gases released from the flue. This is mainly in the form of steam released from the combustion process. A condensing boiler captures some of the heat from these gases and uses it to heat water returning from your central heating system. For the scientifically minded, the latent heat of vaporisation is captured from the steam by condensing it back into liquid water before it exits the exhaust.

Therefore, a condensing boiler requires less heat from the burner to provide the same heating effect in the property, making it more efficient. A condensing boiler is typically at least 25% more efficient than a non-condensing model.

A non-condensing boiler will typically take air in from inside the room, whereas a condensing boiler will be fully sealed and takes in air directly from the outside. Condensing boilers are also safer than non-condensing boilers, as there is a much lower risk of anything being sucked into the boiler. They are also less likely to emit carbon monoxide into your home but must still be properly inspected and maintained to prevent this.

Replacing your boiler

If you are thinking of replacing an old boiler with a new one, you will be buying a new condensing boiler and gaining all of the efficiency savings that come with it. Both combi and heat-only boilers can be either condensing or non-condensing.

Building Regulations now state that all new boilers installed in a domestic home should be high-efficiency condensing boilers, although exceptions do apply in very rare cases. It is also a requirement that they are installed by a suitably qualified professional who should be registered with an appropriate industry scheme. It is very dangerous to attempt this work if you are not fully competent and, if you are unable to prove the work was completed properly, it could affect your ability to sell your home in future. Anyone carrying out work or maintenance of a gas system must be accredited with the Gas Safe Register throughout the UK.

Other considerations

If you decide to change your boiler, the work will be subject to Building Control. Don't let this put you off, but it does mean it will have to be done properly.

In addition to changing your boiler, you may also have to make other improvements to your system at the same time. This can include upgrading the controls you installed, which might mean adding programmers, thermostats, TRVs, weather compensators, smart controls, etc. Your local authority or an expert installer will be able to provide specialist advice on this.

We also give all our clients this top tip: Make sure you don't get given old stock! A new boiler is a big investment so make sure you check the make and model of boiler that is being installed. Make sure that it is a current model and meets the current efficiency standards. we have found that unfortunately even some large installers will "use up" old stock which no longer meets the current standards if they think they can get away with it. Always get at least three quotes before you have the work carried out as prices can vary significantly between different installers for the same work.