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Combi Boiler Replacement Prices & Installation Costs

Luis Antonio Gómez Pérez
By: Luis Antonio Gómez Pérez
Updated: 23rd June 2022

Combi Boiler Replacement

Has your old combi boiler exceeded its recommended useful life? Has it started blinking and taking longer to heat your home than it used to? Have your energy bills increased without increased boiler usage? These all are signs that you need a combi boiler replacement.

Swapping your outdated combi boiler can dramatically improve your heating system's efficiency, which also means lowering your annual heating bills. A new combi boiler can also enable new heating possibilities for your home and prepare it for ongoing changes in the UK aiming to reduce carbon emissions.

In this article, you will learn all about replacing your combi boiler. We will walk you through tips, costs, and benefits of combi boiler replacement so you can make the right choice when looking for the best boiler for your home.

We can also help you save time and effort by finding and sending you up to three free tailormade quotes from heating companies near you. All our partner installers are trusted Gas Safe, and OFTEC registered engineers. Get started by clicking the link below.



Do I need a combi boiler replacement?

In April 2022, energy costs rose across the UK by a drastic 54%, following a sharp increase in global gas prices. The Office of Gas and Electricity Markets (Ofgem) announced it earlier the same year. For you, as a homeowner, this price increase means you would need to spend more money to heat your home than usual.

To minimise the impact on your finances, you can apply energy-saving measures. One of them is replacing your old combi boiler with a new one. Old combi gas boilers' efficiency could be as low as 60-70% due to the boiler wear and tear or because it is an outdated, non-condensing model. Naturally, newer models use less fuel to achieve the same result.

To put it into perspective, a 70% efficiency rate means that you will waste 30p per every £1 you spend on heating your home. Replacing your boiler with a brand new, 94%-efficient condensing combi boiler can save you hundreds of pounds annually.

How much you can save depends on the efficiency of the boiler you are replacing and the property size and type. For example, replacing a 70%-efficient combi boiler in a flat with a 90% or higher one would save you around £150 on your yearly gas bill. A similar combi boiler replacement in a detached house could save you up to £580.

Here is a quick overview of what you can get if you replace your old combi boiler before winter arrives:

  • 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

7 signs that your combi boiler needs a replacement

There are several signs that your combi boiler may not be working well and needs a replacement as soon as possible. Below we'll list the most common ones:

  1. Higher energy bills than usual
    Most likely, this is related to a decrease in your combi boiler efficiency. It could be related to normal ageing or a malfunction.
  2. Radiators take noticeably longer to heat up
    This could just be a blockage in your system, in which case you won’t need a full replacement. However, outdated boilers will take longer to heat your home. You can ask a Gas Safe or OFTEC registered engineer to service your combi boiler to be sure.
  3. Boiler or radiators are making unusual noises
    Frequent humming, vibrating or banging are signs of internal damage or your pipes are congested with ‘sludge‘. If unattended, it could lead to leaking or a complete power outage.
  4. Eggy or sulphurous smell coming from your boiler
    It means there may be a combustion problem and possibly a gas leak.
    ATTENTION: If you smell gas, or suspect there is an emergency, call the gas emergency helpline on 0800 111 999
  5. 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. However, as CO is an odourless gas, the safest measure is to have a CO detector fitted to sound an alarm if the gas escapes.
    If you think that your combi boiler may be unsafe, switch it off and have it checked by a certified engineer as soon as possible.
  6. Your boiler is leaking
    Whilst not always a sign that your combi boiler needs a replacement, frequent leaking is a sign of an ageing boiler. An old boiler is more likely to fall into a structural fault and, therefore, will require constant repairs or, in the worst-case scenario, an emergency repair. These are both strong reasons to upgrade your boilers.
  7. Replacement parts are harder to source
    Getting the parts you need to repair your combi boiler becomes more complicated every time. This could mean the parts and the boiler are outdated, so it would be better if you get a new combi boiler.

What is the lifespan of a combi boiler?

The lifespan of a combi boiler before it needs a replacement is 10 to 15 years. You can prevent it from going out of order prematurely by taking proper care of it. Here are a few tips:

  • Get an annual service
    An annual boiler service is highly recommended to keep your boiler working as efficiently as possible for as long as possible. In many cases, it is also a requirement to keep your combi boiler warranty valid.
    Engineers checking on gas boilers must be authorised and regulated by the Gas Safe register. Those servicing oil boilers need the Oil Firing Technical Association (OFTEC) accreditation.
  • Get repairs fixed ASAP
    If you suspect something is wrong with your combi boiler, try to solve it as quickly as possible. Even minor problems can worsen over time, leading to hefty repair costs.
  • Don’t overwork your boiler
    The more you use your boiler, the shorter its life expectancy. Setting the water pressure too high could also speed up normal wear-and-tear. Thus, moderate use is always recommended. Smart thermostats can help you automatically fire up your combi boiler only when needed.
  • Powerflush
    A certified engineer can add chemicals to your system and flush it through to clear the sludge or dirt built up in your pipes and radiators over the years. This service is called ‘Powerflush’ or chemical flush.
  • Magnetic filters
    Many engineers will recommend magnetic filters to prevent sludge buildup in your heating system. Magnetic filters filter metallic debris before it settles in your pipework or radiators.

Combi boiler replacement cost

A new combi boiler may cost between £500 and £2,000, excluding installation costs. The price of the boiler itself will depend on the brand, model, size, performance, warranty length, special features, etc.

In addition, you would have to consider installation fees ranging from £1,600 to £3,500, depending on factors such as the engineer's rates, the region you live in, the type of boiler you would be installing and the complexity of the installation.

If you already have a combi boiler at home, you will likely replace it with a new combi boiler. In this case, you would be paying around £1,700. It is worth noting that a straightforward replacement is usually cheaper than installing a different type of boiler. Switching to a system or regular boiler would require installing extra components and pipes.

It may be helpful to know that getting quotes from at least 3 heating companies near you is the best way to keep costs low. You would have different options to compare deals and save money, especially on installation costs.

Are you ready to replace your boiler? We can find these quotes for you. Also, replacing your old boiler with a highly-efficient one could save you up to £580 per year on your energy bills. You can get started now.



Compare new combi boiler prices

To help you with your search, we have put together some popular combi boiler series by the most reputable brands in the UK. Whilst they may not be the cheapest on the market, quality and reliability will be assured.

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

Popular combi boiler series in the UK:

  • Brand: Worcester BoschWorcester Bosch Greenstar 4000 combi boiler
  • Series: Greenstar 4000
    Suitable for: from small to medium-sized homes with one bathroom
    Fuel: Gas / LPG model available
    Available Central Heating (CH) outputs: 24kW
    Available Domestic Hot Water (DHW) outputs: 25kW, 32kW
    Efficiency: 94%
    ErP rating: A for heat and A for hot water
    Standard warranty: Up to 10 years
    Typical total cost range (including VAT and installation): £2,000 – £2,500
  • Brand: VaillantVaillant ecoTEC Plus combi boiler
  • Series: ecoTEC Plus
    Suitable for: from properties with up to 10 radiators and 1 bathroom to medium-sized homes with up to 20 radiators and 2 bathrooms
    Fuel: Gas / some models are LPG compatible
    Available Central Heating (CH) outputs: 20.4kW – 32.2kW
    Available Domestic Hot Water (DHW) outputs: 25.4kW – 38.7kW
    Efficiency: 94%
    ErP rating: A for heat and A for hot water
    Standard warranty: 5 years (can be extended to 10 years)
    Typical total cost range (including VAT and installation): £1,952 – £3,003
  • Brand: IdealIdeal Vogue Max combi boiler
  • Series: Vogue Max
    Suitable for: from homes with around 10 radiators and 1 bathroom to properties with around 15 radiators and 2 bathrooms
    Fuel: Gas / LPG compatible
    Available Central Heating (CH) outputs: 18kW, 26kW, 32kW
    Available Domestic Hot Water (DHW) outputs: 26kW, 32kW, 40kW
    Efficiency: 93%
    ErP rating: A for heat and A for hot water
    Standard warranty: 10 years (can be extended to 12 years)
    Typical total cost range (including VAT and installation): £1,889 – £2,623
  • Brand: BaxiBaxi 800 combi boiler
  • Series: 800
    Suitable for: from smaller homes with 1 bathroom to larger properties with a higher demand for central heating and hot water
    Fuel: Gas
    Available Central Heating (CH) outputs: 21.2kW – 34.4kW
    Available Domestic Hot Water (DHW) outputs: 25kW – 40kW
    Efficiency: 93%
    ErP rating: A for heat and A for hot water
    Standard warranty: 10 years
    Typical cost range (including VAT and installation): £1,658 – £2,607
  • Brand: ViessmannViessmann Vitodens 200-W combi boiler
  • Series: Vitodens 200-W
    Suitable for: from smaller homes with up to 10 radiators to properties with around 15 radiators and up to 2 bathrooms
    Fuel: Gas / LPG compatible
    Available Central Heating (CH) outputs: 25.4, 32kW
    Available Domestic Hot Water (DHW) outputs: 30.5kW, 34kW
    Efficiency: 94%
    ErP rating: A for heat and A for hot water
    Standard warranty: 3 years (can be extended to 5 or even 10 years)
    Typical total cost range (including VAT and installation): £2,350 – £2,900

How to choose a new combi boiler

Combi boilers are the most common boiler type installed today. However, not all of them work the same, nor are all combi models suitable for all properties. We recommend you carefully check what kind of fuel the boiler uses, its size (output rating), efficiency, warranty, and price & deals.

  • Fuel: Combi boilers can run on gas, LPG (Liquefied Petroleum Gas), oil, or electricity. Gas combi boilers are the most common and cheapest to run. They take natural gas from the national gas grid. As gas combi boilers burn fossil fuels, they release CO2 into the atmosphere every time they fire up.
    Oil and LPG combi boilers are alternatives for homes disconnected from the grid. Nevertheless, you would need some extra space for fuel storage tanks. Both oil and LPG combi boilers burn fossil fuels, though LPG is slightly cleaner than oil.
    Electric combi boilers are run on electricity and are more energy-efficient than their fossil-fuel-burning counterparts. Their downside is their high running costs, as electricity costs are very high across the UK. Electric boilers don't release CO2; however, most electricity generation in the UK is fossil-fuel-based.
  • Size (output rating): It refers to the boiler's power, measured in kilowatts (kW). Combi boilers have two output ratings: one for central heating (CH) and another for domestic hot water (DHW). Compared to regular and system boilers, combi boilers must be more powerful to achieve the same heating result.The table below shows approximate combi boiler size ranges (in kW) meeting the central heating requirements of different houses.
    Approximate Combi Boiler Sizes (CH Output)
    Houses with up to 10 radiators 24-27 kW
    Houses with 10-15 radiators 28-34 kW
    Houses with 15-20 radiators 35-42 kW
  • Efficiency: All modern combi boilers are highly efficient, thanks to condensing technology. Most of them are 90-94% efficient.
    Tip: The closer they are to 100%, the lower your bills.
  • Warranty: Warranties' duration, terms, and conditions may vary from provider to provider. A good tip is getting a combi boiler with a nice long warranty to ensure peace of mind for as long as possible.
    Most reliable boilers usually come with longer warranties.
  • Price & Deals: Price should not be the determining factor when choosing the combi boiler that best suits your home needs. However, it is always better if you can save some money upfront. In this article, we have already talked about combi boiler replacement costs. You will also learn how to get the best deals on a new combi boiler.

Which boilers can be replaced with a combi boiler?

You can replace any boiler with a combi boiler. However, it is advisable to consider your house's heating and hot water demand before going any further.

Combi boilers work better in homes with 1 bathroom, as they don't store hot water. For example, if two showers are used at the same time, the hot water flow may weaken. Nevertheless, some combi boiler models are powerful enough to meet the hot water demand of a 2-bathroom house.

If combi boilers do not fulfil all your needs, you may also opt for a storage combi boiler. They work like a combi boiler but store hot water in a cylinder, which can be a solution for homes with a high demand for heating and hot water. We could say that storage combi boilers combine the benefits of combi and system boilers.

Replace a system boiler with a combi

Combi boilers are very compact and don't require hot water storage cylinders, making them very simple to install. Nonetheless, if you are replacing an old system boiler with a new combi boiler, you need to account for the time it takes to remove old components or update old pipework.

Replacing a system boiler with a combi, including the hot water cylinder removal, will cost you approximately £2,500.

Replace a regular boiler with a combi

Similarly, replacing a regular boiler with a new combi boiler will cost approximately £3,500. In addition to the hot water storage cylinder, regular boilers include a cold water feed tank, and the installer would also need to remove it.

What happens during a new combi boiler replacement?

The first thing engineers will do during installation is cover the carpets and surfaces they will be working on. It is also advisable to keep the area free of fragile belongings, appliances or furniture, so they don't suffer any accidental damage.

After that, the engineer will cut off your old boiler from the gas and water supplies and then remove it. Before connecting the new boiler, the engineer will clear out any debris (rust, limescale and sludge) from the heating system. The next step is adjusting the pipework or reconfiguring it if necessary.

Finally, the installer will place the new boiler at the specified location and connect it to water outlets, the mains supply, and radiators. If you are replacing a combi boiler with a different type of boiler, they will connect it to additional components such as storage tanks. They may also add accessories such as a system filter or filling loops.

Then, engineers will test the system to ensure everything is working smoothly and safely. At this point, they will call you back to the room to inform you about their work. This is a good time to ask questions about safety and maintenance. Installers will be happy to provide you with all the information you require.

After installation, engineers will also fill out the Benchmark Checklist found at the back of the boiler manual. They will register the installation with the manufacturer to start the warranty. You'll also get a Building Regulations Certificate through the post.

Boiler Replacement Process Summarised:

  • Step 1: Work area preparation (covering surfaces and clearing space)
  • Step 2: Old boiler cut off from gas and water supply
  • Step 3: Old boiler removal
  • Step 4: Clearing out the heating system
  • Step 5: Adjusting the pipework (or reconfiguring it)
  • Step 6: New boiler installation (including gas and water connections)
  • Step 7: System test
  • Step 8: Work report
  • Step 9: Filling forms and getting certificates

How long does a combi boiler replacement take?

How long a combi boiler replacement takes depends on the type of boiler you are replacing it with. Whilst installing a new type of boiler could take 2-4 days, a straightforward boiler swap could take as little as 4-6 hours.

Replacing an old combi boiler with a new one in the same location is the quickest and simplest boiler swap. As we mentioned above, they don't need cold water feed tanks or hot water storage cylinders. Unless there are issues with the current pipework, there is no need for complex plumbing work either.

Getting the best deal on a new combi boiler

As we have already mentioned, a new combi boiler may cost between £500 and £2,000. In addition, installation fees can add from £1,600 to £3,500 to the total cost. You can opt for boiler finance alternatives to pay for your new boiler in monthly instalments. The monthly instalments are usually £20-£30, for as long as you agreed to.

Considering the installation, a fair deal will include fitting a magnetic system filter and powerflushing your system at no extra cost. However, this largely depends on what most installers in your area commonly offer.

However, the best way to lower the new combi boiler and the combi boiler installation costs is to get quotes from at least 3 different heating engineers near you. Comparing them will bring you a range of competitive prices, allowing you to find the best deals for your new combi boiler.

Searching for quotes takes some time, but this is something we can help you with. Just click on the link below, and we will find up to 3 combi boiler replacement quotes from Gas Safe, and OFTEC registered engineers. Our service is free of charge.



Free combi boiler replacement

As you may already know, replacing a combi boiler is not precisely cheap, especially if you need financial support. Fortunately, a range of schemes is available to help UK citizens economise on their new boiler. Still, applicants must match specific criteria.

These schemes can (partially) cover the costs of a new boiler for eligible homeowners. Sometimes, it is even possible to get a new boiler for free. Read our article Free boilers and the Energy Company Obligation to check if you qualify.

Are combi boilers the future?

The UK government targets to achieve a 78% cut in carbon emissions by 2035. If that is the goal, there is no doubt that we need to reduce the amount of fossil fuel we burn to heat our homes. However, it does not necessarily mean saying goodbye to boilers, combi boilers included.

Considering where the future of home heating is heading, it is worth considering combi boiler models that are compatible with renewable heating solutions or that can be used with hydrogen fuel.

Hydrogen is a low-carbon alternative to natural gas. When burned, it doesn’t release carbon, and it could be added to the existing gas network. Even making our current gas supply 20% hydrogen (known as a hydrogen blend) would lower emissions. Find out if hydrogen is a viable option for home heating.

Some combi boiler options already compatible with hydrogen blends are those in the Vaillant ecoTEC Plus range. They can run on a 20% hydrogen blend and can be combined with a hybrid heat pump. These features make them suitable for changes to come in the mid-term future.

FAQ

How often should combi boilers be replaced?

Typically, a combi boiler lasts 10 to 15 years before it needs a replacement. You can prevent it from going out of order prematurely by taking proper care of it.

How hard is it to replace a combi boiler?

It depends on the type of boiler you are replacing your combi with. Replacing an old combi boiler with a new one in the same location is the quickest and simplest boiler swap. Replacing it with a system or a regular boiler will imply installing additional components (e.g. water storage cylinders) and reconfiguring the pipework.

How long does it take to remove and replace a combi boiler?

It depends on the type of boiler you are replacing your combi with. A straightforward combi-for-combi swap could take as little as 4-6 hours. On the other hand, installing a different type of boiler could take up to 4 days.

What happens when a new boiler is fitted?

Below you will find a summary of a boiler replacement process:

  • Step 1: Work area preparation (covering surfaces and clearing space)
  • Step 2: Old boiler cut off from gas and water supply
  • Step 3: Old boiler removal
  • Step 4: Clearing out the heating system
  • Step 5: Adjusting the pipework (or reconfiguring it)
  • Step 6: New boiler installation (including gas and water connections)
  • Step 7: System test
  • Step 8: Work report
  • Step 9: Filling forms and getting certificates

How long do combi boilers usually last?

Combi boilers usually last between 10 and 15 years. However, it could be less if they are not properly maintained.

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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