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How Long Does a Combi Boiler Last?


Combi boilers are popular heating appliances in the UK. They account for more than half of the domestic boilers installed in UK households every year. People love them because they are compact and energy-efficient. Aside from their compact design, Combi boilers supply homes with hot water to taps and showers without the help of pumping systems.

With their bold design and efficiency, it’s easy to see why people are drawn to these boilers. But since they are relatively new to the market, many wonder how long they can last. Unfortunately, the answer to that question is dependent on a couple of factors, including how well you maintain it and the quality of the boiler you purchase.

In this piece, we dive deeper into the life span of Combi boilers and detail how you can prolong their lifespan.

What is the typical lifespan of a Combi boiler?

There are many boiler types and brands in the market. They all differ in quality and hence, longevity. Keep this in mind when looking for a new Combi boiler. You shouldn’t be too focused on saving money in the short term and compromise on the quality. Doing so will eventually cost you more in repairs and a replacement.

Generally, a modern Combi boiler should serve you for 15 years or longer provided it’s of good quality, and it gets regular servicing. When making a purchase, be keen on the warranty offered. The warranty period will give you an idea of how long the boiler should last. Additionally, a warranty will provide you with peace of mind.

How to increase your combi boiler lifespan

  1. Get an annual service

The best way to keep your boiler working efficiently is to service it regularly. Calling a Gas Safe engineer to service the boiler annually is good enough. The Gas Safe engineer will conduct efficiency and safety tests on your boiler to ensure its working at optimum capacity.

The Gas Safe engineer can also check for system leaks and faults. This check will help you catch problems at their early stages. As such, you will end up spending less on repairs. Also, the annual servicing is a requirement for the validity of some warranties.

  1. Get repairs done by Gas Registered engineers

As with annual servicing, repairs should only be handled by Gas registered engineers. Before hiring an expert, conduct a thorough vetting which includes checking for their licensing and insurance. If you don’t have time to vet the expert, look them up on the Gas Safe register. This list consists of heating engineers legally qualified to handle gas appliances in the UK. They meet strict industry standards.

Hiring an unlicensed and unqualified individual may result in more damage to the system. Worse still, the consequences may be dire.

  1. Powerflush regularly

Boiler systems are made up of water and metal. As such, it’s natural that the system will rust and accumulate sludge and dirt over time in the radiators and pipes. This results in blockages, which gradually reduce the system’s efficiency. And when the block remains unfixed for long, the system may sustain severe or permanent damage.

Powerflushing the system involves adding chemicals to the boiler system and flushing them out at high pressure to clear sludge and limescale. This process should only be done by a qualified professional and with the right tools.

  1. Use magnetic filters

Limescale and sludge build-up in the system can be prevented using magnetic filters. These filters trap metallic particles in the water before they settle in the radiators and pipework. Today, most Gas Safe engineers and boiler brands recommend this as a standard.

  1. Choose the right boiler

If you want your boiler to last longer, you have to choose the right one for your home. This means you need to choose the right type (more on boiler type later) and the right size.

Choosing the right boiler size for your home is imperative. If you have a big home, installing a small boiler will cause it to work harder, which means it will wear down faster. It’s more like working for an understaffed company – you will get tired fast.

On the other hand, choosing a large boiler for a small home will translate to wasted energy. The best person to advise on the perfect boiler size for your home is a Gas Safe engineer. But even then, here are several things to consider when making a choice. These include the number of;

  • Radiators
  • People in the room
  • Bathrooms

After making the above considerations, the best Combi boiler for a 2 bedroomed house with 10 radiators and a single bathroom is between 24 kW and 27kW. On the other hand, the best gas boiler for a 3 bedroomed house with 15 radiators and between 2 to 3 bathrooms is between 28 kW and 38 kW. And for a 4 bedroomed house with 20 radiators and more than 3 bedrooms, a boiler with output power between 40 kW and 42 kW is enough.

What type of boiler do I need?

Overall, there are three types of boilers in the UK market. These include:

Combi boiler

This is the most popular boiler in the UK. It is a compact boiler that gets water from the mains (directly) and heats it when needed. This means you don’t have to install a water tank. But on the flip side, these systems aren’t always best for large homes that need to heat large volumes of hot water.

System boiler

This type of boiler also gets water from the mains supply. The system will heat water and direct it to the radiators. However, for the hot water taps, the boiler system requires a hot water cylinder to hold the hot water once it’s heated.

Regular boiler

This is the traditional boiler. It is often found in homes with old heating systems. In this system, cold water is taken from the mains and pumped to a large tank usually located in the attic. The large tank then feeds water to the boiler for heating. From the boiler, the hot water flows to the radiators and a hot water cylinder which supplies the pipes.

Which boiler brands are reputable?

Like many household appliances, there are lots of manufacturers producing boilers in the UK. These boilers differ in reliability, performance, price, and efficiency. As earlier mentioned, the best way to identify a good boiler is by checking the warranty offered. Manufacturer warranty covers labour and parts. The longest warranty is available for 10 years, which often indicates a boiler is reliable and of high quality.

  • Some of the best boiler brands include;
  • Worcester Bosch
  • Ideal
  • Baxi
  • Viessmann
  • Zanussi
  • Alpha
  • Vokera

Why should you replace your old boiler if it’s not working?

If the boiler is more than 10 years and has not yet broken down, you might think it’s unnecessary to replace it. After all, it’s a significant investment that needs careful consideration. But even then, we advise replacing old boilers for several reasons.

Cheaper energy bills

The older a boiler is, the less efficient it gets at heating your rooms. This means it has to work harder to heat your house at the same level it used to when it was new. In the end, the boiler uses a lot of energy to heat water. Replacing it with a modern and efficient boiler means you will experience a significant reduction in energy bills. Some homeowners have experienced a reduction of as high as £305 in a year.

New technology

Modern boilers feature new controls. They are also more compact and visually appealing. These new additions are not only meant to improve their aesthetics but also improve performance and reduce running costs. Modern boilers have internet-enabled thermostats, which affords homeowners remote control through intuitive apps.

Moreover, there are TRVs that can heat individual rooms to different temperatures and weather compensating technology that adjusts the temperature according to prevailing weather.

Home makeovers

If you have added a bedroom, bathroom, extension or have more people in the house, your old boiler might no longer serve the new home. This will lead to a strain on the boiler and an uncomfortable home. A new boiler in such cases is inevitable.

Old boilers don’t have replacement parts

If you are still hanging on to your old boiler, you should know that its replacement parts may no longer be available in the market. When old boilers require replacement parts, it’s difficult for engineers to find them. And even when they do, they are expensive. The repair costs end up being expensive and make replacement the best option.

How much does it cost to replace a boiler?

For a reliable and efficient boiler, you should expect to part with between £1,500 and £2,000. However, the costs vary depending on the size, type and brand of the boiler. The installation costs will depend on the work that needs to be done.

Luckily, our boilers are affordable. There are also financing options you can take advantage of to cover the cost of the project.


How long a Combi boiler lasts depends on various factors. But even then, you have some control over the length of time it will serve you.

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