Hot Water Cylinder Cost UK 2026: Vented, Unvented & Heat Pump Prices
How much does a new hot water cylinder cost in 2026? A like-for-like vented copper cylinder runs £750–£1,400 fitted, while an unvented mains-pressure cylinder such as a Megaflo costs £900–£3,000 installed by a G3 engineer. A heat-pump-ready cylinder is £1,100–£2,200, and replacing just an immersion element starts from about £180. This guide uses real Q2 2026 pricing across 519 UK towns to show what you should actually pay.
Hot Water Cylinder Cost UK 2026: Quick Answer
A vented copper cylinder costs £750–£1,400 fitted and a mains-pressure unvented cylinder (Megaflo, Telford, Gledhill) costs £900–£3,000 installed by a G3 engineer. A heat-pump-ready cylinder with its larger coil is £1,100–£2,200, a thermal store £1,500–£3,500, and an electric immersion-only unit £500–£1,100. Replacing only the immersion element is £150–£280. A straight like-for-like swap is cheapest; a full vented-to-unvented conversion with new pipework and a discharge route is the most expensive. Sizing follows roughly 35–45 litres per person: 120–150L for 1–2 people, 180–210L for 3–4, and 250–300L for 5+. Unvented systems must be fitted by a G3-registered installer, notified under Building Regs Part G3 and serviced annually. London and the South East typically add 15–25%.
Jump to: Cost by type · Vented vs unvented · What size do I need · Heat pump cylinders · Immersion replacement · Running cost & lifespan · Free quotes · FAQs
Hot Water Cylinder Cost by Type
The cylinder type sets the bulk of the price. The two big questions are how the water is pressurised (a vented gravity tank versus a sealed unvented cylinder fed straight off the mains) and how it is heated (boiler coil, immersion element, or a heat pump needing a much bigger coil). The table below shows typical supplied-and-fitted prices for a standard 3–4 bedroom UK home in 2026, including labour, fittings and removal of the old unit but excluding any major rework.
| Cylinder type | Cylinder only | Fitted (supply + install) | Best for |
|---|---|---|---|
| Vented (gravity) copper cylinder | £180–£450 | £750–£1,400 | Keeping a loft-tank system; tight budget; poor mains pressure |
| Unvented (mains-pressure, e.g. Megaflo/Telford) | £450–£2,000 | £900–£3,000 | Balanced mains-pressure showers; multiple bathrooms; no loft tank |
| Heat-pump-ready cylinder (large coil) | £700–£1,800 | £1,100–£2,200 | Air-source or ground-source heat pump installs |
| Thermal store | £900–£2,500 | £1,500–£3,500 | Multiple/renewable heat sources (solar + log + boiler) |
| Electric immersion-only unit (no boiler coil) | £250–£700 | £500–£1,100 | Homes with no gas; flats; Economy 7 off-peak heating |
| Immersion element replacement only | £20–£45 | £150–£280 | Cylinder still sound but no hot water from the immersion |
Figures are Q2 2026 supplied-and-fitted estimates for a 3–4 bedroom home and assume a like-for-like position. Full vented-to-unvented conversions, awkward loft-to-airing-cupboard relocations and London/South East jobs sit at the top of each range or above.
In practice, around two-thirds of cylinder replacements we see are unvented, because homeowners want the mains-pressure shower performance and the freed-up loft space. A thermal store works the opposite way to an unvented cylinder — it stores heated water that warms your incoming mains on demand through a heat exchanger — and is mainly used where you are combining a boiler with solar thermal or a wood burner. The cheapest route is always a like-for-like swap; the cost climbs as soon as you change system type, move the cylinder, or upgrade pipework to feed extra bathrooms.
Vented vs Unvented Cylinder: Which Should You Choose?
This is the single biggest decision and it affects pressure, cost, where the kit goes and your legal obligations. A vented cylinder is fed by gravity from a cold-water tank in the loft, so flow depends on how high that tank sits above the tap. An unvented cylinder is sealed and fed directly from the mains, giving you full mains pressure at every outlet and removing the loft tank entirely — but it is a pressurised vessel, so it is tightly regulated under Building Regulations Part G3.
| Factor | Vented (gravity) | Unvented (mains pressure) |
|---|---|---|
| Water pressure | Low; depends on loft-tank height; often needs a pump | Full mains pressure; strong, balanced showers |
| Cold-water loft tank | Required (plus feed and vent pipes) | None — frees up loft space |
| Fitted cost (2026) | £750–£1,400 | £900–£3,000 |
| Installer qualification | Competent plumber (no G3 needed) | G3-registered installer (legally required) |
| Building Regs Part G3 | Not notifiable | Must be notified to Building Control / Competent Person Scheme |
| Discharge route | Open vent pipe over the loft tank | Tundish + D1/D2 discharge pipe to a safe external point |
| Annual service | Not required | Required yearly (£80–£150) to keep warranty valid |
| Typical lifespan | 15–25 years (copper) | 10–15 years (stainless steel) |
| Mains supply needed | Works on weak mains | Needs good flow, ideally 20+ L/min at 1.5–3 bar |
Before committing to unvented, ask your installer to check incoming mains flow and pressure. A weak supply can underperform on an unvented cylinder, in which case a vented system with a pump, or an accumulator, may be the better answer.
When unvented is worth the extra cost
If you have two or more bathrooms, dislike weak showers, or want to clear the loft for a conversion, the £200–£1,000 premium for unvented usually pays for itself in comfort. The mains-pressure feed means two showers can run at once without the pressure collapsing. The trade-off is the legal overhead: a G3 installer, Building Control notification, a compliant discharge route and a yearly service. Skipping the service is the most common reason unvented cylinders fail early and lose their warranty.
When vented still makes sense
A vented copper cylinder remains the cheapest, simplest option and is a sensible like-for-like replacement if your mains pressure is genuinely poor, you are on a tight budget, or you are not planning to disturb the existing gravity system. Copper cylinders are slower to heat and far less efficient than a modern foam-insulated unit, so if you are replacing an old uninsulated cylinder, even a new vented one will cut standing heat losses noticeably.
What Size Hot Water Cylinder Do I Need?
Sizing is about storing enough hot water to cover your peak demand — usually the morning rush — without over-sizing and wasting energy keeping a big tank hot. The standard rule of thumb is roughly 35–45 litres of stored hot water per person, adjusted for how many bathrooms you have and whether anyone takes baths. As a guide a shower uses around 35 litres and a bath around 80 litres.
| Household | Bathrooms | Recommended size | Typical fitted cost (unvented) |
|---|---|---|---|
| 1–2 people / flat or small house | 1 | 120–150 litres | £900–£1,600 |
| 3–4 people / family home | 1–2 | 180–210 litres | £1,200–£2,200 |
| 5+ people / large or high-use home | 2–3 | 250–300 litres | £1,700–£3,000 |
| Large household / heat pump | 3+ | 300–400+ litres | £2,000–£3,500 |
Size to the property and bathroom count, not just current occupants — a 3-bathroom house should have at least a 250L cylinder so it suits a future family. Heat-pump homes go a size up because the slower reheat means you rely more on stored volume.
Two sizing mistakes cost homeowners money. Undersizing means the cylinder runs cold mid-shower and you wait for it to reheat — annoying with a gas coil, far worse with a heat pump that takes 1–2 hours. Oversizing wastes energy because a larger volume of water loses heat through the day and has to be reheated. The footprint matters too: a 300L unvented cylinder is roughly 1.7m tall and 580mm wide, so confirm it physically fits the airing cupboard before ordering. If space is tight, a slimline or short-and-fat model can hit the same litres in a different shape.
Heat Pump Hot Water Cylinders: Why You Need a Special One
If you are installing an air-source or ground-source heat pump, a standard cylinder will not work well — you need a heat-pump-ready cylinder with a large internal coil. A gas boiler heats water at 60–80°C, so heat moves quickly into the tank through a small coil. A heat pump runs at a much lower flow temperature (typically 50–55°C for hot water), which halves the temperature difference driving heat into the cylinder. To compensate, heat-pump cylinders use a coil with 2–3 times the surface area — around 4.5–6.0m² versus 1.5–2.5m² on a standard cylinder — so the heat pump can still charge the tank efficiently at low temperature.
| Feature | Standard cylinder | Heat-pump-ready cylinder |
|---|---|---|
| Coil surface area | 1.5–2.5 m² | 4.5–6.0 m² (much larger) |
| Flow temperature | 60–80°C (gas) | 50–55°C (heat pump) |
| Reheat time | 20–30 minutes | 1–2 hours |
| Typical size for same home | 180–210 L | 210–300 L (sized up) |
| Fitted cost (2026) | £900–£2,200 | £1,100–£2,200 |
| Legionella protection | Boiler reaches 60°C+ easily | Periodic immersion boost to 60°C cycle |
Because the heat pump stores water at 50–55°C rather than 60°C+, a weekly anti-legionella cycle (usually via the built-in immersion) is built into the controls. This is normal and uses very little electricity.
A heat-pump cylinder is sized up partly for that slow reheat and partly because storing more water at a slightly lower temperature gives a comfortable supply. Brands engineered for low-temperature operation include the Telford Tristar, Mixergy smart cylinders, Joule Cyclone and the Vaillant uniSTOR. If you are pairing this with a new heat pump, the cylinder is usually quoted as part of the whole system — see our air source heat pump cost guide for the full picture, including the £7,500 Boiler Upgrade Scheme grant that can offset the install.
Cost to Replace an Immersion Heater or Element
If you have lost hot water from the electric immersion but the cylinder itself is sound, you usually only need a new element, not a whole new cylinder. The element is the heating rod that screws into the cylinder; it burns out or furs up over time, especially in hard-water areas. Replacing just the element is one of the cheapest hot-water jobs there is.
| Job | Parts | Labour | Total (2026) |
|---|---|---|---|
| Replace immersion element (straightforward) | £20–£45 | £100–£150 | £150–£200 |
| Replace element (seized / tight access) | £30–£45 | £150–£230 | £200–£280 |
| Replace immersion thermostat only | £15–£30 | £80–£130 | £100–£160 |
| New immersion-only cylinder (no boiler coil) | £250–£700 | £250–£400 | £500–£1,100 |
Titanium elements cost a few pounds more than copper but last longer in hard water and are worth specifying. If the cylinder is old, corroded or weeping, replacing the whole cylinder rather than chasing repairs is usually the better spend.
The most common reason an element job runs to the top of the range is a seized element: years of limescale can weld the boss so tight that removing it risks splitting an old copper cylinder, which then has to be replaced anyway. A good plumber will assess this before quoting. If you are replacing the element, it is the natural moment to fit a new immersion thermostat too, since both are accessed together and the thermostat is the cheaper failure point.
Running Costs, Lifespan and Brands
How you heat the cylinder drives the running cost far more than the cylinder itself. A boiler coil heats water cheaply via gas; the electric immersion is more expensive per unit but invaluable as a backup or on an off-peak tariff. At the Ofgem Q2 2026 electricity cap of about 24.7p/kWh, a 3kW immersion costs roughly 74p per hour when actively heating.
| Heating method | Approx. cost | Notes |
|---|---|---|
| 3kW immersion (peak rate, 24.7p/kWh) | ~74p/hour | About £1.50–£2.20/day at 2–3 hrs use |
| 3kW immersion (Economy 7 off-peak) | ~½ the peak cost | Heat overnight on a cheaper night-rate tariff |
| Gas boiler coil | Cheapest per unit | Gas unit rate well below electricity; fast reheat |
| Heat pump coil | Lowest running cost | Delivers 3–4 units of heat per unit of electricity |
| Annual unvented service | £80–£150/year | G3 engineer; required to keep warranty valid |
Running costs use the Ofgem Q2 2026 cap of 24.7p/kWh for electricity. Off-peak Economy 7 night rates and gas unit rates are lower, which is why a boiler or heat-pump coil should do the everyday heating and the immersion is best kept as a backup.
Lifespan and brands
A modern unvented stainless-steel cylinder lasts around 10 years, and 12–15 with annual servicing and soft water. Older copper vented cylinders can run 15–25 years but waste far more heat. The leading UK brands are below.
| Brand | Known for | Positioning |
|---|---|---|
| Megaflo (Heatrae Sadia) | The default premium unvented cylinder, often specified by name | Premium |
| Telford (Tempest / Tristar) | Strong warranty cover; good heat-pump range | Mid – upper |
| Gledhill (StainlessLite Plus) | Best value — close to Megaflo performance for less | Mid |
| Newark / OSO | Widely fitted, reliable workhorse cylinders | Mid |
| Mixergy / Joule | Smart and heat-pump-optimised cylinders | Specialist |
Whichever brand you choose, an unvented model must be installed by a G3-registered engineer and serviced annually. Watch for warning signs of a failing cylinder: dripping from the discharge pipe outside, fluctuating water temperature, banging noises or visible corrosion.
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Compare no-obligation quotes from local Gas Safe and G3-registered plumbers for a new vented, unvented or heat-pump cylinder, a vented-to-unvented conversion, or a simple immersion element swap. Tell us your household size, number of bathrooms and current system and we will match you with vetted installers who can quote on the right size and type for your home.
Get My Free Quotes →Hot Water Cylinder Cost FAQ · UK 2026
In 2026 a new hot water cylinder typically costs £750–£1,400 fitted for a vented copper cylinder, £900–£3,000 fitted for an unvented mains-pressure cylinder such as a Megaflo, and £1,100–£2,200 for a heat-pump-ready cylinder. A direct like-for-like swap sits at the lower end, while a full vented-to-unvented conversion with new pipework and a discharge route reaches the upper end. London and the South East typically add 15–25%.
Choose unvented if you want mains-pressure hot water, balanced flow to multiple bathrooms and no cold-water loft tank, and you have a good incoming mains supply (ideally 1.5–3 bar and around 20 litres per minute). Choose vented if your mains pressure is poor, you want the cheapest fit, or you are keeping a gravity system. Unvented gives a better shower but costs more, must be fitted by a G3 installer and needs an annual service.
Replacing only the immersion element usually costs £150–£280 in 2026, including parts and labour. The element itself is £20–£45 (copper or longer-life titanium) and labour is typically £100–£200 depending on access and region. A seized element or a corroded cylinder takes longer, and fitting a new immersion thermostat at the same time can nudge the total higher. London labour rates sit at the top of the range.
As a rule of thumb, allow roughly 35–45 litres of stored hot water per person. For 1–2 people a 120–150 litre cylinder is usually enough, for 3–4 people aim for 180–210 litres, and for 5 or more people or homes with several bathrooms choose 250–300 litres or more. Size to the property and bathroom count rather than current occupants — an undersized cylinder runs out of hot water and an oversized one wastes energy reheating.
Yes. A heat pump runs at a much lower flow temperature than a gas boiler, so it needs a cylinder with a large internal coil — typically 4.5–6.0m² of surface area versus 1.5–2.5m² on a standard cylinder. The bigger coil lets the heat pump transfer heat efficiently at 50–55°C. Heat-pump-ready cylinders are also usually larger to allow for slower reheat. A standard cylinder will not heat properly on a heat pump, so a like-for-like swap is not suitable.
G3 is the Building Regulations qualification required to install or service any unvented hot water cylinder over 15 litres in the UK. A G3-registered installer is trained in the safety devices, expansion vessels, pressure relief and discharge requirements of a sealed pressurised system. The work must be notified to Building Control, usually via a Competent Person Scheme, and you should receive a compliance certificate. Using a non-G3 fitter is unsafe, can void the warranty and breaches Building Regulations.
A modern unvented stainless-steel cylinder typically lasts around 10 years and often 12–15 with annual servicing and in soft-water areas. Copper vented cylinders can last 15–25 years but are far less efficient and slower to recover. Hard water, a failed expansion vessel, system sludge and skipped servicing all shorten cylinder life. Persistent dripping from the discharge pipe, fluctuating temperature or visible corrosion are signs a cylinder is nearing the end of its life.
Yes. An unvented cylinder should be serviced every year by a G3-registered engineer, typically costing £80–£150. The service checks and recharges the expansion vessel, tests the temperature and pressure relief valve, the expansion relief valve and the tundish, and inspects the discharge pipework. Skipping it is the most common reason an unvented cylinder fails early and almost always voids the warranty. A vented cylinder has no pressurised safety devices and needs no such service.
Converting from a vented gravity system to an unvented mains-pressure cylinder typically costs £1,300–£3,000 in 2026. As well as the new cylinder you pay to remove the old cold-water loft tank and feed pipework, run a new mains feed, fit the safety group and create a compliant discharge route to outside via a tundish. The work must be done by a G3 installer and notified to Building Control. The reward is mains-pressure showers throughout the home with no loft tank.
At the Ofgem Q2 2026 cap of about 24.7p per kWh, a 3kW immersion heater costs around 74p per hour to run. A typical household using the immersion for two to three hours a day spends roughly £1.50–£2.20 a day, or about £45–£65 a month. Heating water on a gas boiler or heat-pump coil is cheaper per unit, so the immersion is best used as a backup or on an Economy 7 off-peak rate where the overnight unit price is much lower.
Megaflo (Heatrae Sadia) is the best-known premium unvented cylinder and is often specified by name. Telford and Gledhill are strong mid-range choices, with Gledhill StainlessLite Plus offering close to Megaflo performance for less and Telford well regarded for warranty cover. Newark and OSO are also widely fitted. For heat pumps, look for large-coil low-temperature models such as Telford Tristar, Mixergy and Joule. Any unvented model must be installed by a G3 engineer.
You should not install an unvented cylinder yourself. By law any unvented system over 15 litres must be fitted by a G3-registered installer and notified to Building Control, because a pressurised cylinder without correct safety devices is dangerous. A simple vented copper cylinder is not restricted in the same way, but it still involves draining the system, soldered joints and correct venting, so most homeowners use a qualified plumber. DIY work can void warranties and invalidate home insurance.
Continue Your Hot Water Research
Sources & How We Price
Our cost ranges are built from Q2 2026 supplied-and-fitted quotes provided by Gas Safe and G3-registered plumbers across our network of 519 UK towns, cross-checked against published trade and manufacturer pricing. Running costs use the Ofgem Q2 2026 electricity price cap of 24.7p/kWh. Regulatory and safety guidance is taken from UK Building Regulations Approved Document G (Part G3), the Chartered Institute of Plumbing and Heating Engineering (CIPHE), the Association of Plumbing and Heating Contractors (APHC), the Gas Safe Register and the BPEC G3 unvented scheme, alongside published specifications from cylinder manufacturers including Megaflo (Heatrae Sadia), Telford, Gledhill and Newark.
- UK Building Regulations Approved Document G — Part G3 (sanitation, hot water safety & water efficiency)
- Chartered Institute of Plumbing and Heating Engineering (CIPHE) — hot water and unvented guidance
- Association of Plumbing and Heating Contractors (APHC) — installer standards
- Gas Safe Register and BPEC G3 unvented certification scheme
- Ofgem energy price cap, Q2 2026 (electricity 24.7p/kWh)
- Manufacturer specifications — Megaflo (Heatrae Sadia), Telford, Gledhill, Newark, Mixergy, Joule
All prices are estimates for guidance only and will vary by property, region, cylinder size and the condition of existing pipework. Always obtain itemised written quotes from G3-registered installers before committing. Read our /editorial-standards for how we research, price and review our cost guides.
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