How long does a combi boiler last?

Combination (or ‘combi’) boilers are a popular choice in UK households, accounting for well over half of all new domestic boilers fitted in the country each year. These compact appliances serve as a central heating boiler and high-efficiency water heater in one, hence their name. As well as saving space, these boilers deliver hot water to showers and taps at mains pressure with no need for a pump. 

It’s certainly not hard to understand their appeal, but how long can you expect a combi boiler to last in your home? The answer to this will depend on a range of factors, including the quality of the appliance and how well you look after it. Keep reading to find out why you should select your next boiler with care, and how regular servicing can make it last longer. We also suggest some simple fixes that may help if you spot a problem with your boiler, and outline how much you can expect to pay to get a new one.

These boilers can differ widely in terms of their quality and longevity, and it’s important to be aware of this when you’re searching for a new model for your home. Saving money in the short term by opting for the cheapest model you can find may ultimately end up costing you more if the boiler you choose isn’t made to a high standard.

Generally speaking, you can expect modern boilers to last for around 15 years, or potentially even longer if you get a good quality model and service it regularly. Pay attention to the warranties offered with boilers, and to benefit from added peace of mind, consider getting an extended warranty if possible. For example, many Viessmann boilers, including our Vitodens 111-W combi model, are available with extended warranties of up to 10 years.

Knowing when to replace a boiler can be tricky. By replacing it too soon, you may be getting rid of a perfectly good boiler that could have lasted another couple of years. But leave it too late and you could end up with no heating and hot water, resulting in an emergency call out. Neither of these scenarios is ideal, so how do you know when a boiler needs replacing?

Generally, older boilers are less efficient than their newer counterparts. The older they get, the less efficient and less reliable they can become, and so if you’ve noticed an increase in the cost of your gas bill, an old or faulty boiler may be the culprit. Often, the issue is that the boiler may use a lot of gas in order to heat your home to the temperature you require. A newer model may need less gas to reach the same outcome, therefore saving you money.

You should also listen out for any unusual noises that could be a sign that your boiler is struggling. These can include groaning, clanging, tapping or hissing that may come from the radiators, the pipes or the boiler itself. Both new and older systems can start to fill with sludge and limescale if the correct water treatment process has not been followed, this can reduce system performance. Magnetite (sludge) build-up can cause kettling putting additional strain on the system. To stop this from occurring, the central heating system can be flushed to remove the contaminated water and allow it to flow freely through the pipes and radiators. In more extreme cases, the boiler may suffer component damage and could need replacing altogether.

Finally, you should check that the boiler flame is blue in colour. An orange or yellow flame may indicate that the burner isn’t burning correctly. This can result in the production of carbon monoxide and could be dangerous.

If you notice any of the above, it might be time to get an opinion from a heating engineer. However, if your 10-year-old boiler is running well and isn’t making unusual noises, such as hissing or clanking, then it may not need replacing. You should continue to get it serviced every 12 months, while listening and looking out for any signs that it may be about to fail.

Servicing your boiler will cost you, but it’s a worthwhile investment as it will likely save you money in the long term, both in terms of your boiler itself as well as energy efficiency. Getting this appliance assessed by an engineer once a year (or more often if you notice any problems with it) will help to ensure it stays in good working order. During a service, your engineer will conduct important checks on everything from the heat exchanger to the electrical connections and seals. They will also ensure your boiler is operating at the right pressure, replace any damaged or worn parts and clean components as necessary. Read our complete guide for homeowners to learn more about what is included in a boiler service.

Identifying and fixing any problems quickly through regular servicing can help you to avoid bigger and more expensive faults further down the line. It can also play an important role in optimising the lifespan of your appliance. On the other hand, if you skip services, you could be storing up trouble for the future. You may also invalidate your warranty.

Servicing is essential in terms of safety too. Arranging regular checks of this appliance will minimise the risk of potentially dangerous faults going undetected, such as carbon monoxide leaks.

If your boiler suddenly stops working or develops a fault, this doesn’t necessarily mean you need to order a new one. Many problems can be fixed, and sometimes the solution is surprisingly simple. If you’re wondering how to fix a combi boiler, here are some suggestions that can help you to address basic problems.

If you’ve experienced a power cut recently, the timer on your boiler may have reset without you realising it. The fix for this is a straightforward timer reprogramming. If you’re not sure how to do this, check the instruction manual provided with the appliance.

To work effectively, combi boilers need to operate at the correct pressure. If the pressure is too low, your boiler may not heat your home properly, while if it’s too high, there might be a problem in the system that could cause serious damage if left unresolved. Most gas boilers have an operating pressure of 1-1.5 bar, and this is usually shown on the pressure gauge as a green zone. If the gauge on your appliance is showing there is a problem with the pressure, you may be able to adjust it yourself by following the instructions in the manual.

If your boiler has a reset function, try using it to see if this brings it back to life. If the appliance was made before 2004, it will probably have a pilot light instead of a reset function. Check to see if this is on. If it isn’t, you may be able to relight it yourself using the instructions in the manual.

If your heating isn’t coming on when you expect it to, try turning your room thermostat up to 21℃. It may simply be that your heating is failing to come on because your rooms are already at the desired temperature.

If it’s cold outside and your boiler isn’t coming on, it may be that the condensate pipe is frozen. You can check this by locating the pipe where it exits your house to run into a drain. If the pipe is frozen, pour warm water over it until the ice has melted. You can then reset your boiler and it should start working as normal.

If these suggestions don’t fix the problem, or if you notice a more serious fault with the appliance, make sure you call in a heating engineer to take a look.

New combi boilers vary in price. The amount you pay for a new appliance will depend on a range of factors, including the brand, specification and size of boiler you go for. Also, bear in mind that as well as factoring in the cost of the boiler itself, you’ll need to budget for installation.

The cost of a new combi boiler for a small property tends to be in the region of £600 to £1,500, while for a terraced or semi-detached house, you can expect to pay between £700 and £2,000. Appliances that suit detached homes generally come in at between £900 and £3,500. Meanwhile, for installation, simply replacing an existing combi may cost approximately £600, while semi-replacing a conventional boiler is likely to be more expensive at around £700. To install a combi boiler in a new location, you can expect to pay around £1,100.

If you’re getting extras with your new boiler, for example a power flush of your existing heating system, a new thermostat or new radiators, you will also face additional costs for these.

When buying a new combi boiler, you might find you’re tempted to go for the cheapest option, but this can prove to be a false economy. Make sure the appliance you select is designed and built to last, and get it fitted by a Gas Safe registered installer. By doing this, and getting the appliance serviced regularly, you will ensure it lasts for many years to come.

Even if your boiler is not approaching the end of its life, you may wish to consider updating it earlier as part of a plan to make your home more energy efficient - particularly if you are making changes to your property such as new insulation, adding solar panels or implementing a smart home package. The cost of your boiler replacement may well be significantly offset by the immediate energy savings you could experience.