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Updated: June 5, 2024

Although combi and regular boilers are different in some ways, it’s not such a bad idea to replace your conventional boiler with a combi one. You just have to make sure that a combi boiler can meet the hot water and heating demand of your home. 

Generally speaking, replacing any type of old boilers is a great improvement since new boilers use condensing technology and are much more efficient. In short, you will pay less money on energy bills to achieve the same end. Condensing boilers can also help reduce your carbon footprint if that is your concern. 

Without a doubt, combi boilers have many advantages. There are many reasons as to why you should replace your conventional or regular boiler with a combi boiler. These pros will be discussed in this blog. 

Best Condensing Boilers

How much does it cost to replace a regular boiler with a combi boiler?

A new combi boiler cost between £500 to £2,000 (without installation cost). The price of a new combi boiler depends of different factors such as:

  • Brand
  • Model 
  • Size
  • Efficiency 
  • Warranty length 
  • Other special features

The installation costs can vary based on different regions in the country, the rates of your heating engineer. However, the main factor that affects the price of installation is the complexity of the job at hand.

This is the most complex and costly kind of boiler swap. It is estimated that you would spend around £3,500 to replace your regular boiler with a combi boiler. The tasks involved in the process are many such as removal of both the hot water cylinder and the cold water tank as well as laying new pipework reconfiguration. 

Why should I replace my regular boiler with a combi?

There are several benefits to replacing your regular boiler with a combi one. These include:

  • Improving your home’s energy efficiency by up to 30%.
  • Reducing your energy bills.
  • Improve safety as there will not be a high risk of carbon monoxide.
  • A combi boiler can increase the value of your property.
  • Reducing your carbon footprint. 

The main advantage is reduced energy use. New top combi boilers use condensing technology and therefore can greatly reduce your energy consumption. So you will be spending less money on heating. 

What is more, combi boilers are compact and small in size so you will be saving space at home. They don’t need a cold water tank or a hot water cylinder. Regular boilers require a cold water tank and a hot water cylinder so they can take a lot of space. 

Combi boilers can also provide hot water instantly. If you run out of hot water with a regular boiler, you’ll have to wait for the boiler to heat water and refill the hot water cylinder. This is just not the case with combi boilers. 

That being said, keep in mind that combi boilers are better suited for small homes as they might struggle to meet the high hot water demand of a large property. If you have a larger home and still want a combi boiler, then you should consider getting a storage combi boiler.

Storage combi boilers have a hot water cylinder for storing hot water so they are like a blend between combi and system boilers. 

Boiler Installation

Signs that your regular boiler needs to be replaced

Although a heating engineer should be consulted on the matter, there are some signs that you can notice yourself which indicate if your boiler should be replaced. 

  • You might notice that you are getting higher energy bills than usual. It can happen with old boilers as they start to lose their efficiency over time. 
  • Unusual noise coming from your boiler or radiators. These noises might sound like a frequent humming, banging or vibrating noise. They can indicate either internal damage or that the pipes are blocked with sludge. 
  • Your radiators need longer time in order to heat up. It goes without saying that old boilers can take longer to heat your household. 
  • You might see some dark stains on your boiler or find out that the pilot light has changed from blue to yellow. This can indicate carbon monoxide leak. 
  • Sulphurous or eggy smell coming from your boiler. This can mean that there is probably a gas leak or a combustion problem. 
  • Boiler is constantly leaking. Leaking that happens frequently can be a sign of an aging boiler. 
  • With an old boiler, you will find out that replacement parts are harder to find. So fixing your boiler won’t even be an available option. 

Read more about:

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Electric Boilers v Gas Boilers

best boilers in uk


Can I replace my regular boiler with a combi boiler?

Of course you can. In fact you can replace your regular boiler with any type of boiler you want (combi or system).

Which boiler is cheaper to run, combi or regular?

The running cost of a boiler depends on its efficiency and output rating rather than the boiler’s type. In short, the higher the efficiency, the cheaper the running cost will be, given the fact that we are talking about boilers of the same size. 

What are the advantages of combi boilers?

Combi boilers are compact in size so they can save you some space in your home. They can provide hot water for your taps, showers and heating system. What is more, they take water directly from the mains and provide hot water on demand. They don’t require a cold water tank or a hot water cylinder. 

Is it easy to replace my regular boiler with a combi?

Well, not particularly. This is one of the most complicated boiler swaps. New pipework might be needed as well as removal of both the cold water tank and the hot water cylinder.