COST GUIDES
Tankless water heater cost guide 2026
Updated 06/26
Tankless water heater cost:
Tankless water heaters for domestic use tend to cost between £150 and £1,000
Average cost:
As an average cost, it's wise to budget around £875 for a tankless water heater
Tankless water heater installation:
Installation costs normally average around £425
Good to know:
Electric tankless water heaters tend to be cheaper to buy than gas models. Tankless water heaters are also known as instantaneous or on-demand water heaters
If you're looking for an energy-efficient way to provide hot water on demand, a tankless water heater could be worth considering.
Unlike traditional systems that store hot water in a cylinder or tank, tankless water heaters heat water only when you need it. That can mean lower energy use, more available space and an endless supply of hot water.
In this guide, we'll look at tankless water heater costs, installation prices, the different types available and the factors that can affect what you'll pay.
How much does a tankless water heater cost in 2026?
Most homeowners can expect to pay somewhere between £150–£1,000 for a tankless water heater, with an average unit cost of around £875.
You'll then need to budget for the installation of your tankless water heater, which often comes in at around £425.
The final price will depend on the type of heater you choose, the fuel source, the complexity of the installation and whether any upgrades to your existing plumbing, gas supply or electrical system are required.
| Type of water heater | Cost + VAT (Range low - high) | Average cost |
|---|---|---|
| Tankless water heater cost (all types) | £150–£1,000 | £875 |
| Electric tankless water heater cost | £150–£575 | £362.50 |
| Gas tankless water heater price | £340–£1,000 | £670 |
| Installation cost | - | £425 |
| Commercial gas tankless water heater | £5,000–£7,500 | £6,250 |
| Last updated: June 2026 Our costs are ballpark averages - get a local tradesperson to quote now | ||
It's often the installation costs that surprise people most. A straightforward replacement may be relatively simple, but first-time installations can call for additional plumbing, electrical or gas work.
Get a quote for a tankless water heater installation
Whether you're replacing an older system or installing a tankless water heater for the first time, it's worth getting a few quotes before making a decision.
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What is a tankless water heater and how does it work?
A tankless water heater heats water as it's needed rather than storing it in a tank or cylinder.
You may also hear them referred to as:
Instantaneous water heaters
Instant water heaters
On-demand water heaters
When you turn on a hot tap, cold water flows through the unit and is heated immediately before reaching your shower, bath or tap.
Because there's no stored hot water sitting in a tank, these systems can be more energy efficient than traditional water heaters and often take up far less space. You also don't have to wait for a tank to reheat once the hot water has run out.
For balance, tankless water heaters aren't the perfect solution for every property. If several people regularly use hot water at the same time, you'll need to make sure the unit is correctly sized to cope with demand.
Tankless water heater costs at a glance
Average tankless water heater cost: £875
Average installation cost: £425
Electric tankless water heater cost: £150–£575
Gas tankless water heater cost: £340–£1,000
Commercial gas tankless water heater cost: £5,000–£7,500
Typical installation time: a few hours to one day
Tankless water heater costs by type
The right tankless water heater for your home will depend on your hot water demand, available fuel source and budget.
Electric tankless water heater cost
Electric tankless water heaters are one of the most popular options for homes with lower hot water demand.
Because they don't require gas pipework or flue systems, installation can be simpler and more affordable.
Average cost: £150–£575
They're often used in smaller homes, annexes, garden rooms and extensions where installing a larger hot water system wouldn't be practical. They're also popular for supplying hot water to a single shower room or utility space.
One thing to bear in mind is that electric tankless water heaters rely entirely on your electricity supply. In the event of a power cut, you won't have access to hot water until power is restored.
Gas tankless water heater cost
Gas tankless water heaters are more commonly used as whole-house systems, supplying hot water throughout a property from a single unit. They're often chosen for family homes where several bathrooms, showers or taps may be used throughout the day.
Gas tankless water heaters generally provide higher flow rates than electric models, making them a popular choice for larger households where several people may be using hot water at similar times.
However, this can also mean installation is more involved and may require additional gas pipework, which can increase costs.
Average cost: £340–£1,000
While the upfront cost is usually higher, many people find they're a good option where demand for hot water is greater.
Commercial gas tankless water heater cost
You'll often find commercial tankless water heater systems in hotels, leisure centres, shower blocks, sports facilities and other buildings where there's a consistent demand for large volumes of hot water.
Due to their size and performance requirements, costs are significantly higher than domestic models.
As a guide, commercial gas tankless water heaters typically cost between £5,000–£7,500, with an average cost of around £6,250.
Commercial installations are usually more complex and should always be priced on a project-by-project basis.
What about tankless water heater brands?
If you've started researching tankless water heaters, you'll probably have come across brands such as Rinnai, Navien and Noritz, each of which offers slightly different features, capacities and efficiencies.
Rinnai tankless water heater cost
Rinnai is one of the best-known tankless water heater manufacturers and offers a wide range of gas-fired continuous-flow systems for domestic and commercial use.
As a guide, Rinnai tankless water heaters typically cost between £395–£1,530, with an average cost of around £962.50.
The price you pay will depend on the model, output capacity and features you choose. Larger and higher-capacity models will naturally cost more than smaller domestic units.
Navien tankless water heater cost
Navien tankless water heaters are known for their high efficiency and are commonly used in homes where multiple bathrooms or outlets may be in regular use.
As a guide, Navien tankless water heaters typically cost between £823–£1,263, with an average cost of around £1,043.
Costs vary depending on the specific model selected and the level of performance required.
Noritz tankless water heater cost
Noritz has been manufacturing tankless water heaters for decades and offers a range of domestic and commercial systems.
As a guide, Noritz tankless water heaters typically cost between £394–£1,300, with an average cost of around £847.
As with other manufacturers, prices will vary according to the model, capacity and specification.
While different manufacturers offer different features and efficiencies, the best model will depend on factors such as your property’s usage, available fuel source and installation requirements. A qualified installer can help you decide which model is most appropriate.
What affects the cost of a tankless water heater?
The price of a tankless water heater installation can vary quite a bit from one project to another.
Some of the main factors include:
Fuel source
Size and capacity
Brand
Energy efficiency rating
Whether it's a replacement or a first-time installation
Existing plumbing configuration
Existing gas or electrical supply
Accessibility of the installation location
Any upgrades needed to pipework or electrics
For example, replacing an existing unit in the same location is usually far simpler than installing a brand-new system where additional services need to be run.
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Additional costs to budget for
When planning your budget, it's worth allowing for a few potential extras.
These can include:
Removal of an existing water heater
Additional insulation (to protect and increase the efficiency of the heater)
Pipework alterations
Annual servicing and maintenance
It's always worth asking your installer for an itemised quote so you can see exactly what's included.
What's included in a tankless water heater installation quote?
Although every installer works slightly differently, most quotes will typically include:
Supply of the water heater (where applicable)
Plumbing connections
Testing and commissioning
Basic materials and fittings
Removal of existing equipment (if agreed)
When comparing quotes from different installers, check whether disposal costs, electrical work or gas upgrades have been included.
How long does it take to install a tankless water heater?
Most tankless water heater installations take anywhere from a few hours to a full day.
A straightforward replacement in the same location is often completed relatively quickly.
However, if new gas pipework, electrical upgrades or significant plumbing alterations are needed, the work may take longer and increase the overall cost.
Are tankless water heaters worth it?
The upfront cost is often higher than a traditional water heater, but tankless systems can be more energy efficient, last longer and free up valuable space.
They're particularly appealing if you've ever run out of hot water halfway through a shower or found yourself waiting for a cylinder to heat back up.
That said, they aren't the perfect solution for every property. Homes with very high simultaneous hot water demand may need a larger unit or multiple heaters.
And while running costs can be lower, the upfront purchase and installation costs are often higher than traditional systems.
As with many home improvements, the best choice depends on how your household actually uses hot water day to day. An experienced installer will be able to help guide your decision.
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How do you maintain a tankless water heater?
Tankless water heaters are generally lower maintenance than traditional storage systems, but they still benefit from regular care.
To keep your system running efficiently:
Arrange annual servicing
Descale the unit annually where required
Clean filters in line with manufacturer guidance
Check for leaks or unusual performance issues
Address faults promptly before they become larger problems
One thing many homeowners don't realise is how much hard water can affect performance. Regular descaling can help maintain efficiency and extend the lifespan of the unit.
Should you install a tankless water heater yourself?
In most cases, installing a tankless water heater is not a job for a DIY enthusiast.
Gas-fired units must be installed by a Gas Safe registered engineer, while electrical work may fall under Part P of building regulations and require a qualified electrician.
There's also the challenge of safely removing existing equipment and ensuring all plumbing connections are completed correctly.
A mistake can lead to leaks, poor performance, property damage or serious safety risks.
Tips for keeping tankless water heater costs down
To help keep costs under control when considering tankless water heater installation:
Choose a heater that's appropriately sized for your needs
Compare multiple quotes
Reuse existing services where possible
Schedule work alongside other plumbing projects
Ask for an itemised quote
Avoid paying for features you don't need
Many people assume bigger automatically means better. In reality, choosing a unit that's correctly sized for your household is often the most cost-effective option.
Tankless water heater installation checklist
When should you speak to a tankless water heater installer?
If you're replacing an ageing water heater, experiencing reliability issues or planning a renovation, it's worth speaking to an installer early in the process.
A quick conversation can help you understand whether a tankless system is suitable for your property and avoid spending money on a unit that isn't properly matched to your hot water demand.
Find a tankless water heater installer near you
Choosing the right water heater for your property is only half the job. Correct installation is just as important for safety, efficiency and long-term performance.
Compare quotes from checked plumbers and heating engineers working in your area and find the right installer for your home.
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Tankless water heater FAQs
How much does it cost to install a tankless water heater in the UK?
Tankless water heater installation typically costs around £425, on top of the cost of the unit itself. Total supply-and-fit costs vary depending on the type of heater, installation complexity and any additional work required.
What is the downside to a tankless water heater?
The biggest downside of tankless water heaters is the higher upfront cost. Tankless systems generally cost more to buy and install than traditional storage water heaters.
Can you run two showers at the same time with a tankless water heater?
Many whole-house tankless water heaters can handle multiple outlets at once. However, this depends on the unit's flow rate and your household's hot water demand.
How long does a tankless water heater last?
A well-maintained tankless water heater can often last 20 years or more, which is typically longer than a traditional storage water heater.
Is a gas or electric tankless water heater better?
Neither is universally better. Gas systems tend to suit larger households with higher hot water demand, while electric models are often cheaper to buy and easier to install.
Do I need planning permission to install a tankless water heater?
In most cases, you won’t need planning permission to install a tankless water heater. However, installation must comply with relevant building regulations and safety requirements, so it's always worth checking with your installer before work begins.
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