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myCombi Boiler Installation Cost
At a Glance
- The average combi boiler installation cost is around £2,500 in the UK.
- Fitting a new combi boiler takes approximately 1 - 2 days to complete.
- How much it costs to fit a combi boiler, as well as what impacts the prices you're quoted by a heating engineer.
- How long fitting a new combi boiler takes, what additional jobs you can schedule at the same time, and expert advice from tradespeople on MyJobQuote.
- How to find and hire a local heating engineer in the UK.
Looking into how much you should expect combi boiler fitting prices to be in 2025?
In short, the average cost of a combi boiler installation is around £2,500. However, the prices you're quoted by tradespeople will depend on a variety of factors.
In this guide, we cover everything you need to know about the cost of a new combi boiler.
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£2,500
Table of Contents
- How Much Is a Combi Boiler?
- How Much Does a New Combi Boiler Cost? (Supply Only)
- Additional Combi Boiler Installation Costs
- How Much to Fit a Combi Boiler? (Labour Only)
- What Is a Combi Boiler?
- What Impacts Combi Boiler Installation Costs?
- What Are the Different Types of Combi Boiler?
- What's Involved in Installing a Combi Boiler?
- Can I Install a Combi Boiler Myself?
- What Size Combi Boiler Do I Need?
- Building Regulations for Combi Boiler
- Benefits of Combi Boilers
- Cost of Combi Boiler Removal
- Hiring a Combi Boiler Installer Checklist
- FAQs
- Sources
How Much Is a Combi Boiler?
The cost of a new combi boiler will depend on a couple of factors. These include the size of the boiler that you will need and the system that you will be replacing.
In the simplest case, where you are replacing an old combi boiler with a new one you can expect to pay between £975 and £2,125. This would include a small 24kW to 27kW boiler. A larger 35kW to 42kW boiler would cost £1,245 to £3,500.
If you are changing to a combi boiler from another type of boiler, then your prices will be higher. For a small 24kW to 27kW boiler, you can expect to pay £1,575 to £2,925. A larger 35kW to 42kW boiler would cost £1,845 to £4,500.
I’m looking at buying a property with a back boiler, what would the likely cost be of removing this and replacing with a combi boiler?
"I would say between £2,500 and £3,500. Combi boiler fitting costs can vary as there are a lot of different situations — I've done many and they all are different."
Combi Boiler Prices
The cost of installing a new boiler depends not only on your new boiler but also on the boiler that it is replacing.
To help you identify your costs, we have split the prices based on the system that your new boiler is replacing. The prices reflect a gas combi boiler since 95% of the boilers bought in the UK are gas.
Replacing an Existing Combi Boiler
| Power Output Of New Boiler | Average Cost |
|---|---|
| 24 – 27 kW | £975 – £2,125 |
| 28 – 34 kW | £1,00 – £2,700 |
| 35 – 42 kW | £1,245 – £3,500 |
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Changing Location of Combi Boiler
| Power Output Of New Boiler | Average Cost |
|---|---|
| 24 – 27 kW | £1,225 – £2,325 |
| 28 – 34 kW | £1,250 – £3,000 |
| 35 – 42 kW | £1,445 – £3,800 |
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Changing Type of Boiler
| Power Output Of New Boiler | Average Cost |
|---|---|
| 24 – 27 kW | £1,575 – £2,925 |
| 28 – 34 kW | £1,600 – £3,500 |
| 35 – 42 kW | £1,845 – £4,500 |
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How Much Does a New Combi Boiler Cost? (Supply Only)
The cost of a new boiler will depend on the size of the boiler as well as the type of fuel it uses. The following tables will give you an idea of the prices you can expect to pay.
What's the quietest and most efficient combi boiler on the UK market?
"Worcester are probably the best combi boilers on the market, they work on demand — no hot water / thermal store required."
Gas Combi Boiler Prices
| Power Output | Average Cost |
|---|---|
| 24 – 27 kW | £475 – £1,425 |
| 28 – 34 kW | £500 – £2,000 |
| 35 – 42 kW | £745 – £2,800 |
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Oil Combi Boiler Prices
| Power Output | Average Cost |
|---|---|
| 24 – 27 kW | £1,300 – £1,900 |
| 28 – 34 kW | £1,500 – £ 2,200 |
| 35 – 42 kW | £1,750 – £3,000 |
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LPG Combi Boiler Prices
| Power Output | Average Cost |
|---|---|
| 24 – 27 kW | £1,000 – £1,500 |
| 28 – 34 kW | £1,250 – £1,750 |
| 35 – 42 kW | £1,500 – £2,000 |
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Electric Combi Boiler Prices
| Power Output | Average Cost |
|---|---|
| 9kW | £1,500 – £2,500 |
| 12kW | £1,500 – £2,500 |
| 14+ kW | £1,500 – £2,500 |
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Additional Combi Boiler Installation Costs
When you are getting your new boiler, there are a few things that might impact the price. There are also jobs you might want to do at the same time. If you can make space for these extra jobs in your budget, it will save you money overall.
Boiler Relocation Cost
If you are not only replacing your old boiler but also moving its location, then there may be some added costs. Modern condensing boilers need to have a drainpipe to remove the condensed vapour.
You will need the boiler to be located where this can be fitted. So, this can increase the cost of installation a little.
The average cost to move a boiler is around £725. However, you will likely be quoted a little less than this if you schedule this work at the same time as fitting a new boiler.
Bleeding Radiators Cost
Bleeding radiators should form part of the process of installing your new boiler. It involves letting the air out of the central heating system. It is a job that you may need to repeat a few times once the boiler is in place.
On average, bleeding a radiator costs around £100 to get done by a professional. However, the prices you're quoted will typically be lower if you're having other work done at the same time.
New Radiators Cost
If you've been thinking of getting new radiators installed, then it'll work out more cost-efficient if it's done at the same time as getting a new boiler installed.
The average radiator replacement costs around £200 and it doesn't usually take more than about 2 hours for a professional to complete.
Cost to Move a Radiator
Moving a radiator can completely change the feeling of a room. If you're having a new combi boiler installed, this is the perfect opportunity to relocate radiators in your home.
The typical cost of moving a radiator is around £200 in the UK. Moving a radiator normally takes between 2 to 5 hours per radiator.
Power Flush Cost
Power flushing is the best practice when it comes to getting a new boiler fitted. Some tradespeople will include this in the cost of fitting a new combi boiler, but this isn't always the case — so ensure you confirm this ahead of time.
If charged seperately, you should expect power flush costs to be between £200 and £500.
How Much to Fit a Combi Boiler? (Labour Only)
The labour costs of installing a new boiler will vary depending on what the new boiler is replacing. If you are simply replacing a combi boiler with a new one, then the process is quite simple.
It should cost around £500 to £700. New combi boiler installations can be done in a single day — taking between 4 and 6 hours.
How much does a combi boiler installation cost (labour only)? Could I also get a price for replacing 11 radiators (4 doubles, supply and labour)?
"I would say roughly £400 to £800 for the boiler installation if it's a straight swap, but if it's a conversion, then it could be anything up to £1,000.
For the radiators, I would say it's a days work (if all went well), so between £300 and £400."
For the radiators, I would say it's a days work (if all went well), so between £300 and £400."
If you need to change the location of your boiler, then the job will take a little longer and cost a little more. You can expect to pay £750 to £1,000. The job should take 1 to 2 days to complete.
The most complex option is where you are changing the type of boiler. This could mean changing the fuel type, or from a system boiler to a combi boiler.
The cost and timescale are about the same in both these situations. Here the combi boiler installation cost will be around £1,100 to £1,500. In this situation, the new boiler installation can take between 2 and 3 days to complete.
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What Is a Combi Boiler?
A combi boiler is a boiler that can provide both the central heating and hot water supply for a home. It does this using water directly from the mains, so there is no need to have either a hot or cold water storage tank.
They have become popular because they are energy-efficient and convenient. They can supply water at the same pressure as you get it from the mains.
Combi boilers are ideal in smaller homes. They can struggle to supply water in homes with more than two bathrooms. They can really only supply hot water for one task at a time. So, they may not be the best choice in larger homes.
All modern combi boilers will also be condensing boilers. This means that they do not have a flue, and they are more efficiently able to use the heat they create. They are safer than non-condensing alternatives. In most cases, you are required by building regulations to have a condensing boiler installed.
What Impacts Combi Boiler Installation Costs?
There are two main considerations when it comes to combi boiler cost: first is the boiler itself, and second is how difficult it will be to install.
Size of Boiler
The larger the output of the boiler, the more it will cost. Basically, a heater for a large home will cost more than a heater for a flat.
Type of Combi Boiler
If you need anything other than a gas-powered boiler, you will be paying more. Gas combi boilers are the most popular choice. Combi boiler prices increase when you need a nonstandard fuel, like oil or LPG.
Location of Property
Labour costs are higher in some areas of the country. London, in particular, sees the highest labour costs of any part of the UK.
Ease Of Access
If it is difficult for your plumber to access the pipes that they need, then the job may take longer. This can increase the cost of the job. If possible, it can be a good idea to get your boiler replaced when you are having other work done, like replacing flooring, for example. This can make access easier and reduce your costs.
Size Of House
The size of your home can impact the cost in two ways. First, if you have a larger home, you will need a larger boiler. The second is that it can take longer to install if there is any work needed on the pipes.
How much does it cost to replace a gas back boiler and fire with a new heating system, including a combi or condenser boiler and 7 radiators, in a terraced house with an attic?
"Anything from £3,500 to £5,000 once everything is confirmed — i.e., boiler, radiators, pipework, location, fittings, room thermostat, removal, and making good."
What Are the Different Types of Combi Boiler?
When you choose your new boiler, there are a few options for the type of fuel it uses. Your choice of fuel may be limited by your location. If you can't get a gas supply, then you will need to look at the alternatives. Since the only difference between these boilers is the fuel. The choice will depend on how easily you can access each fuel type.
Gas Combi Boiler Cost
These are the most commonly installed type of combi boiler. If you have access to gas, this is often the best choice. The running costs will be the lowest.
The average cost of a gas combi boiler is £500 to £1,900.
Oil Combi Boiler Cost
If gas is not an option, then the next choice is likely to be oil. You will need to have an oil tanker installed outside your home to supply your boiler. This means you will need to make arrangements to have the tanker refilled as needed.
The average cost of an oil combi boiler is £1,300 to £2,700.
LPG Combi Boiler Cost
LPG combi boilers run in almost the same was as a gas one. The only difference is that the gas comes from an external tank. Again, you need to make arrangements to keep it refilled.
The average cost of an LPG combi boiler is £1,000 to £2,000
Electric Combi Boiler Cost
Electric combi boilers work a little differently. They use a system similar to an immersion heater to heat the water supply. They are often used only when the other options are too expensive or impractical. They are much more limited in the size of home that they will work for. Running costs can be high.
The average cost of an electric combi boiler is £1,500 to £2,500
What's Involved in Installing a Combi Boiler?
Before the day of the installation, you should have a conversation with your installer about the boiler that you want. Often, your plumber will be able to source the boiler for you, and they may be able to get a better price. It is also an opportunity to check that the boiler you want is appropriate.
On the day, the first step that many plumbers will take is to lay down protective covers on the floor to protect them while they work. Some water spillage is hard to avoid.
It is considered best practice to perform a power flush of the central heating system before the new boiler is installed. This is to remove any rust or debris that has built up in the system over time.
The next step will depend on the boiler system that you currently have.
Replacing an Old Combi Boiler With a New One
If you already have a combi boiler, then the process is quite straightforward. Once the gas and water are turned off, the old boiler will be removed.
Then, the new boiler will be mounted to the wall. If the boiler is the same power rating as the old one, it should fit in the exact same place. Once the boiler is in place, the gas and water are reattached, and the system is tested.
Moving Your Boiler or Changing Type of Boiler
The process is quite similar when you need to move your boiler or if you need to change it to a new type. The first step is to disconnect the old system.
This will involve taking away the old boiler and securing the gas and water connections that are no longer needed. If you have water tanks, they can be left in place and removed at a later date.
The new location for the boiler will then need to be prepared. The engineer may need to add in new pipework for the water supply and drainage as well as the gas works.
Once all of this is done, the new boiler can be mounted on the wall and connected up. The whole system will be tested before the engineer is done.
Can I Install a Combi Boiler Myself?
A boiler must be installed by a registered, competent person. This is to ensure that the work is safe and that it meets building regulations. Working with gas can be dangerous, which is why this is not a DIY job.
What Size Combi Boiler Do I Need?
The size of the boiler you need will depend on your home. The bigger your home, the bigger your boiler should be. It usually depends on the number of radiators and bathrooms.
If your boiler is too small, it might not be able to keep up with the demand. If it's too big, you can waste energy and money running it. The following table can provide some guidance.
| Number of Radiators | Number of Bathrooms | Boiler Output |
|---|---|---|
| 1 - 10 | 1 | 24 – 27 kW |
| 11 – 15 | 2 - 3 | 28 – 34 kW |
| 16 - 20 | More than 3 | 35 – 42 kW |
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In some cases, the size of your boiler might be dictated by your water pressure, but this is rare, and your installer can check this for you.
Building Regulations for Combi Boiler
Building regulations do apply to the installation of boilers. There are requirements that cover how it should be installed, as well as the types of boiler that can be installed.
All installations must be carried out by suitably registered competent people. For gas, this means Gas Safe registered. For oil boilers, this means using an OFTEC-registered installer. If your installer has these qualifications, then you can be reassured that they will complete the work in line with the requirements of Approved Document J.
When you use a registered competent person to complete your installation, they will be able to self-certify that the work was completed to the correct standard.
If you do not use a registered installer, you will need to arrange for an inspection once the work is complete.
Is it possible to have a boiler installed in a bathroom?
"You can have a boiler fitted in a bathroom, but there are regulations regarding electrical equipment and various zones in the bathroom. To comply, you would either need a very large bathroom or the appliance would need to be boxed in. A bathroom is not the ideal location for a boiler."
Building regulations require that all new boilers that are installed meet minimum efficiency standards. This means that any boiler you buy will already meet the required standard.
In almost all situations, you will be required to get a condensing boiler installed. Again, it is almost impossible to buy a boiler that does not meet this requirement.
It is important that your boiler meets building regulations. If it does not, it can be dangerous for your family. It will also not be cheap to fix the problem.
To find out more about how building regulations might apply to your situation, you can go to the government's online planning portal. Otherwise, you can speak to someone in the planning department of your local council.
Benefits of Combi Boilers
Combi boilers are a modern choice. They have become popular because they offer a wide range of benefits over the alternatives.
High Energy Efficiency
All combi boilers are required to be 92% efficient. This means that only 8% of the energy put in is wasted. This is a very high level of efficiency and will save you money and reduce your carbon footprint.
Lower Bills
If your current boiler is quite old, it could be a non-condensing model. These were, at best, 55% efficient. If your boiler is from before 2018, it could have an efficiency of around 70%, even if it is a condensing boiler. For the average household, moving from 70% to 92% efficiency can lead to an annual saving of around £300.
Compact
Combi boilers don't need storage tanks. They are a single contained unit that can often fit into a kitchen cupboard or in a utility room. If you have a water tank, you can get all that space back.
Easy Installation
Because a combi boiler is contained in a single unit, installation is relatively easy. Easy installation also means it is cheaper to install. An added bonus is that you can put it pretty much wherever you want in your home, as it doesn't have to connect to storage tanks.
On-Demand Hot Water
One of the biggest benefits of a combi boiler is that heats water on demand. That means you don't have to worry about running out of hot water. When you need hot water, you turn the tap on. Then, in under a minute, you have hot water flowing.
Main Water Pressure
A Combi boiler uses water directly from the mains. This means your hot water is supplied at that pressure. It is no longer reliant on gravity like in a tank-fed system.
Cost of Combi Boiler Removal
It is unlikely that you will want to remove a combi boiler unless you need to replace it with a new boiler. The cost of removing your old boiler will usually be included in the installation price of your new boiler.
However, if you are removing the old one in advance of getting a new one, it will not cost too much money. A combi boiler is quite simple. You will just need to cap off the connections. It should only take an hour or two and will cost around £200.
A boiler is considered to be a commercial waste, so it can be a challenge to get rid of it. You may need to contact a specialist company to take it away. In most situations, you would expect the plumber to dispose of it for you. This is usually included in their installation costs.
Hiring a Combi Boiler Installer Checklist
Getting a new boiler can sometimes be a decision that is made in haste. If your old boiler has broken down, then you may be pressed for time. However, there are some things you should take the time to check before you choose your heating engineer.
- If your boiler is gas-run, then you need to know that your engineer is gas safe registered. It is a legal requirement to work with gas.
- OFTEC registered – If your new boiler is oil-powered, then your installer must be OFTEC registered to be legally allowed to complete the work.
- Check that any heating engineer you are considering hiring is insured to complete the work you need. This protects both you and them in case of an accident.
- A good engineer will be able to explain to you the system and what they are going to do. If they can't answer your questions, you should avoid using them.
- Online reviews can give you a lot of insight into a tradesperson. If the person you are looking at has a lot of negative reviews, it can be worth looking elsewhere.
FAQs
How does a combi boiler work?
A combi boiler takes water directly from the mains. It then uses its fuel, usually gas, to heat it in a system called a heat exchanger. This allows the water to be heated very quickly. The hot water is then supplied straight to your tap at mains pressure.
What type of shower can you have with a combi boiler?
Combi boilers run off mains pressure. This means that they can work with any type of shower.
What temperature should hot water be set at combi boiler?
The temperature that you choose for your water is a matter of preference. If your aim is to save money, the best settings are to have the hot water at 60 degrees and the radiators at 75 degrees.
How long should a combi boiler last?
You can expect a modern combi boiler to last around 15 years.
Are combi boilers an energy-efficient option?
Current regulations require that all new combi boilers be at least 92% efficient. You can easily find boilers that are as much as 95% to 98% efficient. This is significantly better than the generation of boilers that came before them. So, if you are upgrading to a new combi boiler, it will almost certainly be significantly more efficient than your old boiler.
Sources
https://www.planningportal.co.uk/permission/common-projects/boilers-and-heating/building-regulations
https://www.greenerkirkcaldy.org.uk/
https://lloydsgas.co.uk/blog/what-are-the-different-types-of-boiler-an-ultimate-boiler-guide/
