• Blog
  • Replacing a regular boiler with a combi boiler 

    • home
    • Blog
    • Replacing a regular boiler with a combi boiler 

  • Blog
  • Replacing a regular boiler with a combi boiler 

    • home
    • Blog
    • Replacing a regular boiler with a combi boiler 

    Updated: February 26, 2024

    If a combi boiler can meet your home’s hot water and heating demand, then you can go ahead and replace your conventional boiler with a combi one. Combi boilers can save space at home due to their compact design. 

    Generally speaking, replacing an old boiler with a new one, regardless of the type, can improve the efficiency of your heating system and probably save you some money on energy bills. Another benefit if that you be able to reduce your carbon footprint. 

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

    A new combi boiler can cost between £500 and £2,000, excluding the cost of installation. Factors such as the model, size (output rating), brand, special features, efficiency and warranty length can determine the exact cost of your new combi boiler. 

    As for the installation cost, this will depend on the complexity of the installation. Replacing a regular boiler with a combi one can entail various tasks. 

    This is one of the most expensive and complex boiler replacements. The process involves removal of the cold water feed tank, removal of the hot water cylinder and new pipework setup reconfiguration. 

    Why replace your regular boiler with a combi boiler?

    • To improve the efficiency of your home by 30%
    • To reduce your energy bills. A combi boiler is very efficient
    • To improve safety and prevent gas leak. 
    • To reduce your carbon footprint 
    • To increase the value of your property 

    New condensing boilers actually use less fuel than old boilers. So when you improve the efficiency of your heating system, you will be able to reduce your energy bills and as a result save money. 

    Other reasons for replacing your regular boiler with a combi is that a combi boiler can save you some space in your home as well as provide hot water instantly.

    Combi boilers are known for being small and compact in size. They can usually be placed inside a regular kitchen cupboard. What is more, they will take water directly from the mains, heat up the water and send it around your home. This process eliminates the need for both a cold water feed tank and a hot water cylinder. 

    With conventional boilers, you will have to wait for the hot water cylinder to refill once you have used all the available hot water. On the other hand, combi boilers can instantly heat the water that is directly taken from the mains and feed it to your showers and taps. 

    That being said, combi boilers are better suited for homes with 1 bathroom as they may struggle to supply hot water to more than one shower at the same time. However, some combi boiler types are powerful enough to meet the high demand for hot water for 2 bathrooms. 

    Another option is available for those who want a combi boiler that is suitable for home with multiple bathrooms. You may want to consider getting a storage combi boiler. It operates just like a combi boiler with the addition of having a hot water cylinder for storing hot water. In short, these boilers are like a combination of combi and system boilers. 

    Replacing A Regular Boiler With A Combi Boiler 
    Replacing A Regular Boiler With A Combi Boiler  4

    What are the advantages of combi boilers?

    How water on demand 

    Combi boilers are great when it comes to providing hot water on demand. On the other hand, system boilers have to heat the water first and then store it. 


    Combi boilers are quite efficient. They have an efficiency rate of at least 92%. As a result of this, your energy bills will be lower and it can also reduce your carbon footprint. 

    Compact in size

    If you don’t have much space in your home, then a combination boiler is the perfect choice for you. Combi boilers are compact in size and don’t take up much space. They can even be fitted inside a kitchen cupboard.

    Easy installation 

    Combi boilers are very easy to install since they do not require either a cold water tank or a hot water cylinder. This will save you both time and money.

    Replacing A Regular Boiler With A Combi Boiler 
    Replacing A Regular Boiler With A Combi Boiler  5

    When to change my regular boiler?

    There are some signs that would indicate the need for boiler replacement. These may include:

    • Your radiators will take longer to heat than usual. Old boilers tend to take longer time to heat your home.
    • You will get higher energy bills. This will happen as a result of decreased efficiency.
    • You might notice a sulphurous or eggy smell that is coming from your boiler. This can be a sign of a gas leak or a combustion problem.
    • Unusual noises coming from your radiators or boiler. These sounds might sound like frequent humming, banging or vibrating. This might be a sign of internal damage or maybe your pipes are blocked with sludge. 
    • The pilot light has become yellow instead of blue or there are dark stains on your boiler. These signs may indicate a carbon monoxide leak. 
    • It is harder to find replacement parts. That means your boiler has become old and outdated.
    • Another sign of an old boiler is constant leaks.


    Are combi boilers cheaper to run than conventional boilers?

    The running cost of a boiler depends on its output rating and efficiency rather than the type of boiler in question. In short, the higher the efficiency of your boiler is, the cheaper to run it is. 

    Is a combi boiler very efficient?

    Combi boilers are very efficient. They can show 92%-98% efficiency.

    Do combi boilers use gas or oil?

    Combi boilers can use different types of fuel. They can run on gas, oil, LPG (Liquified Petroleum Gas), and electricity.

    Can I change from a regular boiler to a combi boiler?

    Yes, it is possible to change your regular boiler with another type. You would just need to know your home’s heating and hot water demand in order to choose the right boiler.