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Last updated: 2nd January, 2024


Replacing Combi Boiler Guide 2024

Replacing Combi Boiler Guide 2024

Replacing your boiler can be a stressful and costly process. That’s why we have written this helpful article to show you your options when it comes to buying a new boiler.

Switching to a Combi Boiler

Has your boiler stopped working, then you are now in need of a replacement, you should consider replacing it with a combi boiler if you haven't already got one.

Combi boilers are a brilliant replacement for when you want to increase efficiency and space in your home. We have a great range of best combi boilers available through iHeat.

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A combi or combination boiler combines a water heating system and central heating unit into a single body, acting as a unified way to handle heating and hot water without needing two separate boilers and produces hot water on demand.

This means there is no need for a separate water tank system and therefore takes up much less space in your home, which is a major benefit for smaller homes.

Viessmann Worcester Combi Boiler

Another great benefit of a combi boiler is its efficiency. By heating water on demand as opposed to constantly heating stored water, you can save energy and cut costs on your fuel bills.

A new combi boiler should be around 90% efficient, so replacing your old boiler could save you up to £300 according to The Energy Saving Trust.

You can find out more about swapping to a combi boiler here.

Getting an A Rated Efficient Boiler

The efficiency of your boiler plays an important role in how well your boiler operates as well as the cost of your fuel bills.

The higher the efficiency of your boiler, the lower your fuel costs. The Energy Saving Trust estimates that you could save up to £300 a year by replacing your old inefficient boiler with a new A-rated one (90%+ efficient).

All iHeat boilers are A-rated for efficiency, so you know you can rely on us to help you save money and reduce your carbon footprint.

Buying Your Boiler on Finance

Paying for a boiler on finance spreads out the cost to make it more affordable on a monthly basis instead of paying for it all at once.

With iHeat you can buy a brand new boiler on finance using our super simple to use website with an instant quote and fixed price.

We offer great plans such as 0% APR for 2 years or as little as £10.32/month for 10 years. These prices include the boiler, installation and up to 10 Years Warranty which is activated by the installer as soon as the job is done.

Boiler On Finance

Relocating your boiler

At iHeat, we’re happy to move your boiler from one place in your home to another, providing it is practical.

For example, if your old boiler was taking up far too much room in your kitchen cupboard, you can replace it with a boiler that fits in your airing cupboard. However, you should consider if moving your boiler is worth the extra labour cost.

The Size of Your Boiler

When we talk about boiler size, we’re often referring to the output in kilowatts (kW) as opposed to the physical dimensions of the boiler itself. Kilowatts are the measurement of energy that is output by the boiler in the form of heat.

The right kW boiler for your home depends on a number of factors, including your demand for hot water, the number of bedrooms, bathrooms and radiators.

In general, the higher your demand for heat and hot water, the higher the output you will need.

Size of Home

No of Bedrooms

No of Bathrooms

No of Radiators

Boiler Size

Flat / Bungalow



Up to 10


Medium terrace/semi-detached



Up to 15


Large semi-detached/detached



Up to 20


Different Size Homes Boilers

Considering these options before buying a new boiler can really help you to save money on the boiler, installation and fuel bills that follow.

For a free fixed quote for replacing your boiler, click here. For more information, visit our FAQs, Boiler Help or alternatively, contact us through our live chat, email or call us on 0333 305 6880.

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0% APR finance available.

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Frequently Asked Questions

How much does a gas boiler replacement cost in 2024?

In 2024, the cost of a gas boiler replacement can vary greatly based on the type of boiler you choose and the specific installation requirements in your home. Expect to pay between £1,500 and £2,500 for a combi boiler, with higher-end models costing more. Keep in mind that this price range includes the boiler, installation, and any necessary adjustments to your heating system.

How much does it cost to fit a boiler in the UK?

The cost of fitting a boiler in the UK depends on several factors, such as the type of boiler, the brand, and installation costs. Generally, a boiler installation can range from £1,500 to £4,500 for a combi or system boiler. It's important to note that these prices can vary depending on your specific needs and region.

What are the average combi boiler prices in the UK?

The average price of a combi boiler in the UK ranges from £1,000 to £2,500, with the higher-end models costing more. This price will typically include the boiler unit itself without installation costs. Remember to factor in the expense of installation when budgeting for a new combi boiler.

How much does it cost to install a boiler in the UK?

In the UK, the cost to install a boiler typically ranges between £500 and £2,000, depending on a variety of factors. These can include the complexity of installation, whether any old equipment needs to be removed and replaced, and the specific requirements of your home's existing heating system.

What is the oil boiler replacement cost for 2024?

In 2024, the oil boiler replacement cost is likely to range from £1,500 to £3,500 for a standard installation. This price may change depending on the complexity of the installation and any additional work or upgrades required to accommodate the new boiler in your home.

What is the cost of a new boiler for a 4 bedroom house?

The cost of a new boiler for a 4 bedroom house depends on the specific heating needs of the property and the type of boiler chosen. For a combi boiler capable of meeting the demands of a larger home, you can expect to pay between £2,000 and £4,000. This price range generally includes the boiler, installation, and any necessary adjustments to your existing heating system.

What will replace gas boilers after 2025?

As regulations change and a push for greener alternatives becomes more prominent, the UK government has announced that new homes built after 2025 will not have traditional gas boilers installed. Instead, alternative heating systems will need to be employed. A few of these systems are already thriving in the market and may become the primary choices for replacement.

One popular option is heat pumps. These devices extract heat from the air or ground, which is then used to heat a home's water and central heating system. Air source and ground source heat pumps are considered eco-friendly and energy-efficient, leading to reduced energy consumption and a lower carbon footprint.

Hydrogen-compatible boilers are also worth considering. These appliances are designed to gradually transition from natural gas to hydrogen as the main fuel source. With no CO2 emissions generated during combustion

Stephen Day profile photo
Article by
Stephen Day | Co-founder
Gas Safe registered and FGAS certified engineer with over 20 years experience in the heating and cooling industry.