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myCombi Boiler Installation Cost
At a Glance
- The average combi boiler installation cost is around £2,750 in the UK.
- It typically takes 1 day for a heating engineer to install a new combi boiler.
- How much a new combi boiler costs in the UK, the labour cost to fit a combi boiler, and what impacts the prices you're quoted in 2026.
- 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.
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£2,750
Table of Contents
- How Much is a New Combi Boiler Installation?
- How Much Does a New Combi Boiler Cost? (Supply Only)
- How Much to Fit a Combi Boiler? (Labour Only)
- What Size Combi Boiler Do I Need?
- Additional Combi Boiler Installation Costs
- What Are the Different Types of Combi Boiler?
- Factors That Impact Combi Boiler Installation Costs
- Building Regulations for Combi Boilers
- What's Involved in Installing a Combi Boiler?
- Combi Boiler Service Costs
- Checklist: Hiring a Combi Boiler Installer in the UK
- FAQs
How Much is a New Combi Boiler Installation?
How much do I need to budget for my new boiler installation?
Replacing your existing combi boiler for a new combi boiler costs between £1,050 and £2,250 for a small 24kW to 27kW combi boiler replacement.
As the power output increases, so do the boiler prices, making a larger 35kW to 42kW boiler between £1,400 and £3,700.
And, if you change to a combi boiler from another type of boiler, your prices will be higher still.
How much does it cost to move your combi boiler to a new location?
If you're moving your boiler to a new location, your installation prices will be higher than a like-for-like swap, usually because condensing boilers require a new drainpipe. The average cost to move a boiler is around £725, though removing your old boiler beforehand typically takes an hour or two and costs around £225 to £300.
What boiler power output do I need for my property?
Combi boilers range from 24kW to 42kW. The right output for your home depends on the number of radiators and bathrooms you have.
I’m looking at buying a property with a back boiler. What would the likely cost be of removing this and replacing it 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 are all different."
Combi Boiler Installation Prices
Now, let's look at some combi boiler installation prices and boiler replacement costs, based on three scenarios:
- Upgrading an old combi boiler with a new combi boiler in the same location
- Upgrading an old combi boiler with a new combi boiler and moving to a new location
- Changing an old system/regular boiler and converting to a new combi boiler
| Installation Type | 24 – 27kW | 28 – 34kW | 35 – 42kW |
|---|---|---|---|
| Combi → Combi (same location) | £1,050 – £2,250 | £1,200 – £2,850 | £1,400 – £3,700 |
| Combi → Combi (new location) | £1,300 – £2,450 | £1,400 – £3,150 | £1,550 – £4,000 |
| System/Regular → Combi Conversion | £1,650 – £3,050 | £1,750 – £3,700 | £1,950 – £4,750 |
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How Much Does a New Combi Boiler Cost? (Supply Only)
Splitting out boiler installation prices now, let's look at the prices of new combi boilers based on their fuel type and power output for comparison.
Starting with gas, oil, and LPG:
Combi Boiler Prices (Gas, Oil & LPG)
| Power Output | Gas | Oil | LPG |
|---|---|---|---|
| 24 – 27 kW | £525 – £1,500 | £1,400 – £2,100 | £1,100 – £1,600 |
| 28 – 34 kW | £575 – £2,150 | £1,600 – £2,400 | £1,300 – £1,850 |
| 35 – 42 kW | £800 – £2,950 | £1,850 – £3,200 | £1,550 – £2,200 |
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Why are electric combi boilers not included in the main cost table?
Electric combi boilers use a different power output range, typically between 9kW and 14kW, which is much lower than gas, oil, and LPG, which is why we've kept them separate as their outputs don't correlate.
Electric Combi Boiler Prices
| Power Output | Average Cost |
|---|---|
| 9 – 12 kW | £1,600 – £2,600 |
| 14+ kW | £1,700 – £2,700 |
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How Much to Fit a Combi Boiler? (Labour Only)
The labour costs of installing a new combi boiler will vary depending on what the new combi boiler is replacing. The process is quite simple if you replace a combi boiler with a new one.
It should cost around £550 to £800 for labour. New combi boiler installations can be done in a single day, taking between 4 and 6 hours.
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 £850 to £1,150 in labour costs, and the job should take 1 to 2 days to complete.
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 day's work (if all went well), so between £300 and £400."
For the radiators, I would say it's a day's work (if all went well), so between £300 and £400."
The most complex option is where you are changing the type of boiler. This could mean changing the fuel type or moving 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 price will be around £1,200 to £1,700 for labour. In this situation, the new combi boiler installation can take between 2 and 3 days to complete.
| Installation Type | Labour Cost | Duration |
|---|---|---|
| Combi → Combi (same location) | £550 – £800 | 4–6 hours |
| Combi → Combi (new location) | £850 – £1,150 | 1–2 days |
| System/Regular → Combi Conversion | £1,200 – £1,700 | 2–3 days |
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What Size Combi Boiler Do I Need?
The right boiler size 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.
It's important to choose the right boiler size:
- If your boiler is too small, it might be unable to keep up with the demand.
- If your boiler is too big, you can waste energy and money running it.
The following table can provide some guidance on the right size for your home:
| 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.
Additional Combi Boiler Installation Costs
During your new boiler installation, you may need some additional work done at the same time. Scheduling jobs together with your installer can save on call-out fees.
Power Flush Costs
Power flushing is the best practice during a new combi boiler installation, but it's especially important in older properties where years of sludge and limescale may have built up in your pipes and radiators.
If you're installing a new central heating system to combat poor heat circulation in your home, you need to make sure you tackle issues in your pipework too, so you feel the benefits of the new system.
Some tradespeople will include this in the cost of fitting a new combi boiler, but this isn't always the case.
If charged seperately, you should expect power flush costs to be around £400, depending on the size of your central heating system.
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."
Smart Thermostat Installation Costs
If you're upgrading your boiler to improve your home's energy efficiency, a good pairing is a smart thermostat. Smart thermostats can save 10% to 12% on your annual heating bills.
Typically, smart thermostat installation costs around £265, depending on the model you choose.
It is estimated that using Thermostatic Radiator Valves (TRVs) to control each room's temperature individually can save households £80 to £165 per year on energy bills.
New Radiator Costs
If you're upgrading your heating system, it's a good opportunity to replace any old or inefficient radiators at the same time.
Radiator replacement costs around £200 per radiator on average, including fitting, though you should budget more if work to your existing pipework or new pipework is required.
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What Are the Different Types of Combi Boiler?
Different types of combi boilers are available, but what's best for your home can be limited by the fuel you can access. So, if you can't get a gas supply, then you will need to look at the alternatives.
Let's go through the different combi boiler types, their pros and cons, and installation costs.
Gas Combi Boiler Cost
These are the most common type of combi boiler installations in the UK. If you have access to gas, this is often the best choice, as your running costs will be the lowest compared to other fuel types.
The average cost of a gas combi boiler is £525 to £2,950.
Pros
- ✔ Lowest running costs compared to other boiler and fuel types
- ✔ Good availability, suitable for small and medium-sized homes
- ✔ Easy to install
Cons
- ✖ Installation needs to be completed by a Gas Safe registered engineer for safety
- ✖ If you aren't close to a gas supply, you can't have this type of boiler
- ✖ Although running costs are typically low, gas prices can change over time
Oil Combi Boiler Cost
If you live off the main gas grid, your next best choice of boiler is likely to be an oil combi. With this boiler type, you'll need an oil tanker fitted outside your home to supply your boiler, which you'll need to refill as needed.
The average cost of an oil combi boiler is £1,400 to £3,200.
Pros
- ✔ Good fuel option for homes living off-grid from the mains gas supply
- ✔ Capable of heating large homes
- ✔ Some oil boilers can be more efficient at heating large homes than older gas boiler models
Cons
- ✖ Requires an oil tank installed outside your home, which can affect your property's aesthetic
- ✖ If deliveries of oil refills are delayed, you can be left without heat
- ✖ The price of oil can fluctuate
LPG Combi Boiler Cost
LPG combi boilers run almost the same way as a gas combi boiler. The only difference is that the gas comes from an external tank, making it a suitable alternative for homes off-grid.
The average cost of an LPG combi boiler is £1,100 to £2,200.
Pros
- ✔ Good option for homes off the main gas grid that still want to use gas fuel
- ✔ Gas burns cleaner compared to oil
- ✔ Installation costs are usually lower than oil combi boilers
Cons
- ✖ LPG boilers need an additional tank to store fuel, taking up a lot of space
- ✖ Running costs are higher than traditional gas combi boilers
- ✖ Deliveries of fuel can be delayed, and regular safety checks need to be conducted to ensure the storage is safe
Electric Combi Boiler Cost
Electric combi boilers 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.
The average cost of an electric combi boiler is £1,600 to £2,700.
Pros
- ✔ Easy to install
- ✔ Good option for homes where gas or oil isn't suitable
- ✔ Small, compact design
Cons
- ✖ Running costs are far higher than gas or oil
- ✖ Not suitable for large homes with high hot water demand
- ✖ Can be slow to heat hot water
Factors That Impact Combi Boiler Installation Costs
There are two main considerations when it comes to combi boiler cost: the boiler itself, and how difficult it will be to install.
- Size of Boiler - The larger the output of the new combi boiler, the more it will cost. Heating a large home will cost more than heating a small, one-bed flat.
- Type of Installaton - The system you're replacing (e.g., whether it's a like-for-like combi swap, or changing from a system boiler to a combi) will affect your new boiler costs.
- Type of Combi Boiler - Gas combi boilers are the most popular choice due to their efficiency and ease of installation. 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 they need, the job may take longer, which can increase the cost of the job.
- Size Of House - You will need a bigger combi boiler if you have a large home with multiple bedrooms, and it can take longer to install if any work is needed on the pipes.
- Brand of Boiler - The brand you choose also affects your overall combi boiler price. Premium brands like Worcester Bosch and Vaillant tend to command higher combi boiler prices but typically offer longer warranties and stronger reliability ratings, and brands like Baxi and Ideal offer a more budget-friendly option.
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."
Building Regulations for Combi Boilers
Building Regulations apply to the installation of combi boilers. Some requirements cover how it should be installed, as well as the types of combi boilers that can be installed.
All installations must be carried out by suitably registered competent people:
- For gas boilers, this means a Gas Safe registered engineer.
- For oil boilers, this means using an OFTEC-registered installer.
- For electric boilers, this means using a qualified electrician who can self-certify under Part P of the Building Regulations.
If your installer has these qualifications, they will complete the work in line with the requirements of Approved Document J. They will be able to self-certify that the work was completed to the correct standard.
Your new combi boiler must meet Building Regulations. If it doesn't, it can be dangerous for your family and expensive to correct.
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.
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."
What's Involved in Installing a Combi Boiler?
Boiler installations are dangerous, and shouldn't be attempted as DIY tasks.
Working with gas can be dangerous, and incorrect installation can result in leaks or carbon monoxide poisoning. Electric boiler installations need to be carried out by a qualified electrician.
With MyJobQuote, you can request several quotes from local combi boiler installers near you. It's fast, free, and there is no obligation to go ahead.
Let's take a closer look at the process of installing a new combi boiler in your home:
Before the Job Starts
- Initial Consultation — Before the day of the installation, your installer will talk to you about the boiler you want, checking that it's appropriate for your house size and usage.
- Prepping the Work Area — Your plumber will lay down protective covers on the floor to protect them while they work, although some water spillage is hard to avoid.
During the Job
- Disconnection — The gas and water supply are safely switched off, and the old boiler is disconnected and removed. If you're changing from a system or conventional boiler, any water tanks or hot water cylinders can also be removed at this stage.
- Prepping the New Location — If you're moving the boiler or changing the type, the new location will be prepped, including any new pipework for the water supply, drainage, gas, and flue.
- Installation — The new boiler is mounted to the wall and connected.
After the Job
- Testing — The new system will then be tested and checked for pressure and leaks.
Combi Boiler Service Costs
For all property types, you'll need periodic boiler servicing to ensure your system is running correctly and that any issues are picked up early before they become major, expensive problems.
A new, A-rated boiler can also lead to lower energy bills over time, particularly if your existing boiler is old or running at low energy efficiency:
- For the average household, moving from 70% to 92% energy efficiency can save around £300 on annual energy bills. With an annual boiler service costing around £100, your yearly saving would be around £200.
- With the average combi boiler installation costing around £2,750, a new boiler could pay for itself in around 14 years.
Checklist: Hiring a Combi Boiler Installer in the UK
Getting a new boiler can sometimes be a decision that is made in haste - especially if your old boiler has broken down.
However, there are some things you should take the time to check before you choose your heating engineer:
- Have you got a range of heating engineer quotes to compare? Gather at least 3 quotes from different traders to compare local prices.
- Are your boiler installation quotes itemised? Make sure the quotes are broken down into individual lines so you can see what's included. Do you need to pay more for extra pipework, waste removal, or relocating the boiler?
- Have you researched the heating engineer? Take a look at the trader's reviews on their MyJobQuote profile, along with any photos or videos of their past work.
- Have you got the correct heating engineer for your fuel type? If your boiler is gas-run, then you need to know that your engineer is Gas Safe registered. If your new boiler is oil-powered, then your installer must be OFTEC registered. Electric boilers need qualified electricians.
- Are they insured? Check that any heating engineer you are considering hiring is insured to complete the necessary work, ideally with public liability insurance. This protects both you and them in case of an accident.
FAQs
How Long Should a Combi Boiler Last?
You can expect a modern combi boiler to last around 10 to 15 years with regular annual servicing. Replacing an old boiler that is over 15 years old with a new combi boiler is usually more cost-effective than paying for repairs over time, and upgrading to a new energy efficient model can also reduce your energy bills.
Can I Buy a Combi Boiler on Finance?
Yes, buying a combi boiler on finance is a smart way of spreading the upfront cost of the boiler and the installation price over a period of time. Depending on the company, you may be offered 0% interest plans, or buy now, pay later schemes - check with your local provider to see what's available for you.
Can I Install a Combi Boiler Myself?
No - you cannot legally install a combi boiler yourself. A combi boiler installation must be completed by a Gas Safe registered engineer. This is to ensure that the work is legal, safe, and meets Building Regulations.
How Long Does a Combi Boiler Warranty Last?
Most new combi boilers come with a warranty of between 2 and 10 years, and some manufacturers require annual boiler servicing to keep the warranty valid. Brands such as Worcester Bosch and Vaillant tend to offer the longest cover, while Baxi and Ideal typically offer shorter cover.
How Much Can I Save With a Combi Boiler?
For the average household, moving from 70% to 92% efficiency can lead to an annual energy bill saving of £300, depending on your usage, so swapping to a modern boiler can bring cost-saving benefits in the long run.
Can I Get a Government Grant for a New Boiler?
Government grants are available to eligible households. The ECO4 scheme can help low-income households with the cost of a boiler replacement, while the Boiler Upgrade Scheme offers grants towards heat pumps as an alternative. Eligibility depends on your household income, benefits status, and your home's energy efficiency rating.
What Is the Best Month to Replace a Boiler?
Spring and summer are the best times to book a boiler replacement, when boiler installers tend to have more availability and labour costs may be more competitive than during the busy winter months.
