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Replace a Conventional Boiler with a Combi Boiler: Costs & Prices

Luis Antonio Gómez Pérez
By: Luis Antonio Gómez Pérez
Updated: 11th July 2022

Replacing conventional boiler with combi

Replacing your old regular or conventional boiler with a brand-new combi boiler is not a bad idea at all. Actually, as long as the new combi meets your home's heating and hot water demands, it is the best you can do to save space at home.

Regardless of the type of boiler you are replacing your old boiler with, upgrading an outdated boiler will improve your heating system's efficiency. This means that you will pay less to achieve the same result. Installing a new boiler can also help you reduce your house's carbon footprint and align better with the UK’s goal of reducing carbon emissions.

However, if you decide to replace your conventional boiler with a system or a combi boiler, you may get additional advantages. In this article, we will focus on the latter, specifically on why to replace a conventional boiler with a combi, its costs, and how to get the best deals.

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

Excluding installation costs, a new combi boiler may cost between £500 and £2,000. Many factors will determine the price of a combi boiler: the brand, model, size (output rating), efficiency, warranty length, special features, etc.

You can also check our boiler comparison tool to find further information.

In addition to the boiler itself, you also have to consider installation fees. How much it costs to replace a conventional boiler with a combi will depend mainly on the engineer's rates, the region you live in, and the complexity of the installation.

It is worth noting that this kind of boiler swap is one of the most complex and expensive boiler replacements. You would need to spend approximately £3,500 to replace a conventional boiler with a combi, including the pipework setup reconfiguration and removal of the hot water storage cylinder and the feed water tank.

In this regard, one of the best and easiest ways to lower the costs and avoid being overcharged is to get quotes from at least 3 different heating engineers. Comparing them will bring you a range of competitive prices, allowing you to find the best deals and save money, especially on installation.

Searching for quotes can take a lot of time and effort, but this is something we can help you with. Just click on the link below, and we will find up to 3 combi boiler quotes from Gas Safe and OFTEC registered engineers near you. It's free of charge and you are under no obligation to accept any of the quotes you receive.



Why replace your conventional boiler with a combi?

Let's start with the general reasons for a boiler replacement. Here is an overview of why you should replace your old conventional boiler with a new combi or any other type of boiler.

  • Reduce energy bills. You can save up to £580 on yearly energy bills
  • Improve your home's energy efficiency by up to 30%
  • Increase your property's value
  • Improve safety (by preventing dangerous gas leaks, such as carbon monoxide)
  • Reduce your house's carbon footprint

As you already know, the global increase in gas prices has also impacted the UK. In April 2022, energy costs rose by a drastic 54% compared to the first quarter of the year.

Replacing your old conventional boiler with a highly-efficient new combi can soften the impact on your finances. New condensing boilers use less fuel than old boilers, so you will spend less money to heat your home.

However, how much you can save replacing a conventional boiler with a combi depends on the boilers' efficiency, property type, and size.

For example, replacing a 70%-efficient regular gas boiler in a flat with a 90% or higher combi boiler would save you approximately £150 on your yearly gas bill. A similar conventional boiler replacement in a detached house could save you up to £580.

Next, we will explain why you should specifically replace your conventional boiler with a combi. It is basically because of these two reasons:

  • Save space in your home
  • Get hot water instantly

Combi boilers are very compact and, usually, can be installed inside a standard kitchen cupboard. Furthermore, they take water directly from the mains water supply to heat up and send it around the home. Thus, they don't need hot water storage cylinders and feed water tanks as conventional boilers do. This is great news for those wanting to save space.

Regarding the hot water availability, as conventional boilers store it in a cylinder, you will have to wait for it to refill every time you use hot water. If you run out of it, you might have to wait quite a long time. So, you better get a big water cylinder if your house's water demand is high.

On the other hand, with a combi boiler, there is no need to wait for the water to heat up or a hot water storage tank to refill before you take a bath or shower. As previously mentioned, they take water from the mains, heat it, and deliver it on demand.

However, you should be aware that combi boilers generally work better in homes with 1 bathroom, as they don't store hot water. This could mean, for instance, that the hot water flow may weaken if two showers are used simultaneously. Nevertheless, some combi boiler models are powerful enough to meet the hot water demand of houses with 2 bathrooms.

You may also consider a storage combi boiler. They work like a combi boiler but store hot water in a cylinder, making them a kind of 'blend' between combi and system boilers.

7 signs that your conventional boiler needs a replacement

Whilst you should always ask for heating engineers' expert opinions, some signs can help you identify if your regular boiler may not be working well. If you find any of the following, it might be time to replace your conventional boiler:

  • Higher energy bills than usual. Most likely, this is related to a decrease in efficiency.
  • Radiators take noticeably longer to heat up. Outdated boilers will take longer to heat your home. You can ask a Gas Safe or OFTEC registered engineer for an expert opinion.
  • Boiler or radiators are making unusual noises. Frequent humming, vibrating or banging are signs of internal damage or your pipes are congested with ‘sludge’.
  • Eggy or sulphurous smell coming from your boiler. There may be a combustion problem and possibly a gas leak.
  • Dark stains on your boiler or the pilot light has turned from blue to yellow. It may indicate there is a carbon monoxide (CO) leak.
  • Your boiler is constantly leaking. Frequent leaking is a sign of an ageing boiler. An old boiler is more likely to fall into a structural fault.
  • Replacement parts are harder to source. This could mean the parts and the boiler are outdated, so it would be better to get a new one.

ATTENTION: If you smell gas, or suspect there is an emergency, call the gas emergency helpline on 0800 111 999.

In any case, if you think that your regular boiler may be unsafe, switch it off and have it checked by a Gas Safe or OFTEC registered engineer as soon as possible.

If the time to replace your conventional boiler has come, we can help you get it done fast and at the best possible price in your area. Click on the link below, and we will send you up to 3 tailor-made quotes from Gas Safe and OFTEC registered engineers near you. It's free of charge and you are under no obligation to accept any of them.



FAQ

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

Yes, you can replace a conventional boiler with any type of boiler, including a combi. However, it is advisable to consider your house's heating and hot water demand before going any further.

Is it easy to change from a conventional boiler to a combi boiler?

Changing from a conventional boiler to a combi is one of the most complex and expensive boiler replacements. In addition to adjusting the pipework configuration, the engineer will need to remove the hot water storage cylinder and the feed water tank.

Is a combi boiler cheaper to run than a conventional boiler?

A boiler's running costs depend on its efficiency and output rating rather than its type. On similarly sized boilers, the higher the boiler efficiency, the cheaper to run it will be.

What are the disadvantages of a combi boiler?

Combi boilers don't store hot water, so the hot water flow may weaken if two showers are used simultaneously. They are recommended for small to medium-sized homes with 1 bathroom. However, some combi boiler models are powerful enough to meet the hot water demand of houses with 2 bedrooms.

Will combi boilers be banned?

You must be aware that the upcoming boiler ban in the UK will affect all types of gas boilers alike: combi, system, and regular boilers. However, it is still unclear when this will happen. Furthermore, it will apply only to new builds, so replacement gas boilers are still fine for existing homes.

In any case, combi boilers will not be banned per se, as they can/could run on fuels other than gas, such as electricity, biomass, and hydrogen (blends).

Luis Antonio Gómez Pérez

About the author

Luis Antonio Gómez Pérez

Trained as a journalist, Luis Antonio has plenty of experience researching and writing about the use of different energy sources for domestic purposes. He also keeps up to date with the future of domestic heating and how traditional and alternative heating solutions may impact household economics.

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