Is a condensing boiler a combi boiler? 

The short answer to that question is yes. However, there are three different types of condensing boiler:

• A combi (or combination boiler) which can provide heating and hot water upon demand.

• A system boiler or heat only (sometimes known as a conventional boiler) which both utilise a tank or cylinder for hot water storage.

Read on to learn what we really mean by condensing and combi boilers. 

Understanding condensing boilers

When talking about condensing boilers, we are actually talking about a certain technology where heat that would normally be lost as part of a boiler’s operation, is reclaimed. This is achieved by extracting the heat from flue gases during combustion. A heat exchanger cools these gases below their dew point, causing the water vapour to condense into liquid form. The latent heat released in this process is used to preheat incoming cold water, significantly reducing fuel consumption.

The energy efficiency of condensing boilers is one of their most significant advantages, with efficiency ratings often exceeding 90%. This high efficiency means more of the energy consumed is converted into usable heat, potentially lowering energy bills. Many modern condensing boilers are equipped with advanced controls that adjust performance based on real-time demand, further boosting their efficiency.

Environmentally, condensing boilers contribute to reducing carbon emissions by utilising energy more effectively. This not only decreases greenhouse gas emissions but also reduces the overall demand for fossil fuels, making them a sustainable heating choice.

Understanding combi boilers

Combination boilers, or combi boilers, combine central heating and hot water supply into one unit. When you need hot water, the combi boiler heats it directly from the mains supply, eliminating the need for a separate hot water tank. This results in hot water on demand, ensuring convenience and efficiency. 

One of the key advantages of combi boilers is their space-saving design. Without the need for a separate hot water cylinder or cold water tank, combi boilers are ideal for homes with limited space, fitting easily into kitchen cupboards or utility rooms. This compact design is especially beneficial for flats and smaller houses.

Another significant benefit is the immediate availability of hot water. With a combi boiler, there's no waiting for a tank to fill or heat up; hot water is instantly available when you turn on the tap. This immediacy enhances comfort and contributes to energy efficiency, as water is heated only when needed, potentially lowering your energy bills

Comparing condensing and combi boilers

Most, if not all, modern combi boilers are, in fact, condensing boilers. Regulations which came into effect in 2005 state that all new and replacement boilers fitted in the UK are required, by law, to be condensing boilers. Given most boilers tend to have a lifespan of around 10 to 15 years, even up to 20 years if they have been well-maintained and serviced, then if you don’t currently have a condensing boiler at the moment, you may in the near future, or opt for an air source heat pump.