The best tankless water heaters, compared.
Top pick: Stiebel Eltron DCE-X 10/12 – Electronic control, a stated 5 L/min and 55°C, and UK reviews of stable basin hot water where a high-current circuit exists. Best value: ThermoMate ET055 5.5 kW – The reviewed hand-wash option at £109.74, with 4.0 from 248 amazon.co.uk reviews, once a 25 A circuit is in place. Updated 17.10.2026.
If the only cold feed is at a cloakroom, a garage sink or a flat with no gas, a tankless water heater warms mains water as it flows and does not hold a cylinder. What matters is the match between kilowatts, incoming temperature and flow, plus a circuit that can carry the current. About 3 kW is the 13 A BS 1363 region. A 6 kW claim is about 26 A at 230 V. The datasheet at 230 V lists 11.0/13.1 kW and a 50/60 A fuse. A new circuit is Part P notifiable work unless a competent-person scheme self-certifies. If you need a washing-up bowl from a normal socket, start with [point-of-use water heaters](/hub/hot-water/point-of-use-water-heater). Two listings have no reviews, and two print conflicting power or size figures.
If the only cold feed is at a cloakroom, a garage sink or a flat with no gas, a tankless water heater warms mains water as it flows and does not hold a cylinder.
26 products checked · 64 hrs invested · +18,600 readers
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Personal buying guide
Question 1 of 2
What do you need the hot water for?
The Stiebel Eltron DCE-X 10/12 is the strongest and most controllable heater in this set, with a listed 5 litres per minute, a 55°C maximum and degree-by-degree electronic adjustment. UK reviewers describe stable hot water at basins and, where the supply is suitable, usable shower service. Its two memory keys, 2-year warranty line and 116-review record make the £412.86 price easier to assess than the cheaper, sparsely reviewed alternatives. The trade-off is electrical: this is a 10/12 kW-class appliance that needs a dedicated high-current circuit and professional installation, not a socket. Reviews also make clear that it is not a bath filler, and one kitchen installation produced disappointing mixer-tap flow. Subject to the circuit and outlet limits, it is our top pick for buyers who need more than low-flow hand washing.
Pros
Cons
Best for: One or two point-of-use outlets, including a suitable shower or basin, where a high-current circuit can be installed
Less suitable: Bath filling, a standard 13 A supply, or projects where the installation cost outweighs the hot-water need
Specifications
Common questions
Can the DCE-X be plugged into a socket?
UK reviews say it cannot. They describe their own circuits at about 40 A to 63 A, with cable from 10 mm² to 16 mm. The listing wattage is 12 kW.
Will it fill a bath?
More than one UK review says no. Reviewers use it for basins and, at the higher setting with suitable electrics, a shower.
What flow and temperature are on the spec table?
5 litres per minute and 55°C, at a stated maximum pressure of 10 bar. Energy class on the listing is A.
The ThermoMate ET055 is a 5.5 kW point-of-use heater aimed at hand washing and remote basins rather than filling a kitchen bowl. Its listing states 3 litres per minute, but UK reviewers report that the flow may need to fall to about 1 litre per minute before the water feels properly warm. The self-modulating control and on-demand operation can avoid running a distant boiler for a small cloakroom draw. With 248 reviews at 4.0 stars, it has a much broader UK feedback base than most of the lower-priced inline units in this comparison. Even so, the specification table's 25°C maximum conflicts with review temperatures in the high 20s and 30s, and the title correctly warns that no plug is included. It is our best-value option for a professionally connected hand-wash basin, not a budget route to normal kitchen or shower flow.
Pros
Cons
Best for: A remote cloakroom or hand-wash basin where short draws and restricted warm-water flow are acceptable
Less suitable: Kitchen bowls, baths, plug-in installation, or users expecting the stated 3 L/min to stay hot in winter
Specifications
Common questions
Does the ET055 come with a UK plug?
The title says no plug. The bullet says the plug and hoses are not included and that the breaker should be 25 A or higher. A style line still says plug-in installation.
What flow does the listing print?
3 LPM in the capacity field. UK reviews include about 1 litre per minute when the water is actually warm, and cloakroom use where that flow was acceptable.
Why does the spec table say 25°C?
Maximum temperature is printed as 25°C. UK reviews describe outlet water in the high 30s or about 29°C from a very cold inlet. The conflict is left as printed.
The TopSer BS-18DC-3 Pro gives a sink its own 3 kW hot-water tap, with a stated flow of 3 litres per minute and no separate storage cylinder. UK reviewers confirm that it heats from the cold feed, but the useful temperature depends heavily on reducing the flow. The flexible hose makes it easier to direct water around a kitchen sink, while the metal body feels more substantial than a small plastic inline box. Installation is not as straightforward as the price suggests: reviewers say the cable may have to be cut to pass through the sink opening, and one notes that the water pipe was not supplied. More seriously, reports of leaks and electric shocks mean this is not a product to fit casually or continue using after the first sign of a fault. It is a low-cost point-of-use option only where modest flow is acceptable and the installation can be checked properly.
Pros
Cons
Best for: A utility or kitchen sink where you need occasional warm water from one cold feed and can accept a slower flow
Less suitable: High-flow washing up, showers, or any installation without competent electrical and plumbing checks
Specifications
Common questions
Does the TopSer tap store hot water?
The listing calls it a tankless electric heater tap. A capacity field of 1.8 litres is printed, which is not a 10 litre undersink store.
How hot does the listing say it gets?
The spec table has no maximum temperature. UK reviews say a slower flow is hotter, and some reviewers report very high temperatures at a low flow.
Is it a shower?
It is a deck-mounted tap. The title names a bathroom, washroom and toilet as well as a kitchen. No shower head is listed.
The Mulcort LF-001 puts 3 kW of point-of-use heating into a compact wall-mounted box that reviewers found easy to fit beneath a vanity. In practice, the available power suits hand washing better than filling a kitchen bowl: UK reviews say the outlet has to be reduced to a trickle before the water becomes properly hot. One buyer returned it because the warmer flow was not sufficient for washing dishes. The LCD and low price make the unit look convenient, but the UK listing mixes 43.2 GPH in the title with a 43.2-gallon capacity field, so those figures should not guide a purchase. Its stated 122°F maximum also appears without a matching verified flow. This is a small-basin heater with clear limits, not a normal-flow kitchen hot tap.
Pros
Cons
Best for: Occasional hand washing at a compact cloakroom or vanity basin where low flow is acceptable
Less suitable: Filling washing-up bowls, supplying a shower, or choosing by the contradictory capacity figures
Specifications
Common questions
Is the Mulcort LF-001 a storage heater?
The title says instantaneous tankless. The capacity field prints 43.2 gallons and the title prints 43.2 GPH. Neither line is a 10 litre tank size.
Will it fill a kitchen bowl quickly?
UK reviews say hotter water means cutting the flow to a trickle, and one reviewer returned it because dish washing needed more heat.
What maximum temperature is printed?
122°F on the spec table. No Celsius maximum is printed.
The Delousiber RY-LZT-4 is advertised as a 6 kW inline heater with a 30–55°C control range, but its electrical presentation is the central problem. The listing calls for a dedicated circuit and a fuse of at least 40 A, while UK reviewers report receiving a unit fitted with a regular plug. That conflict matters because a standard 13 A socket cannot supply a genuine 6 kW load. One reviewer reported about 50°C from two installed units after six weeks, so the heating claim is not unsupported in every case. However, repeated accounts of leaks, blown fuses and units failing within days or weeks outweigh the attractive £46.99 shelf price. Treat it as an unresolved installation and reliability risk rather than a plug-in bargain.
Pros
Cons
Best for: Only a professionally assessed dedicated-circuit installation where the supplied unit matches its data plate and instructions
Less suitable: Anyone expecting a safe 6 kW heater to run from a normal UK socket or wanting proven long-term reliability
Specifications
Common questions
Can this 6000 W heater go on a 13 A plug?
The bullet asks for a dedicated circuit and a fuse of at least 40 A. UK reviews say a regular plug was fitted and that a 13 A socket is not a 6000 W supply.
What temperature does the spec table state?
55°C. The bullet says the range is 30–55°C. No litres-per-minute figure is printed.
What did UK reviews report after fitting?
One review cites about 50°C after six weeks. Others report leaks, blown fuses, and units that stopped within days or weeks.
The laloohome Ewh-6000t promises point-of-use hot water up to 55°C and explicitly calls for a dedicated circuit with a fuse of at least 40 A. That is more credible than presenting a high-power heater as a 13 A plug-in appliance, and mounting hardware plus a manual are listed in the box. The product data is nevertheless inconsistent: the title says 6000 W, the technical details say 5500 W, and two different sets of dimensions appear. There are no UK customer reviews in the extract, so there is no independent evidence here for its temperature control, shower claim or durability. At £44.99 it is inexpensive, but the absent review record and contradictory specification make the true value uncertain. Confirm the data plate and installation requirements before treating any listing claim as settled.
Pros
Cons
Best for: A buyer prepared to verify the exact unit and fund a suitable dedicated circuit before installation
Less suitable: Anyone seeking review-backed performance, a plug-in appliance, or a dependable shower recommendation
Specifications
Common questions
Which power figure is on the listing?
The title and the first bullet say 6000 W. Technical details say 5500 watts. Both are printed.
Are there UK reviews in the extract?
No customer-review line and no review texts. Stars and complaints are not printed.
Does the bullet say it can be plugged into a 13 A socket?
No. The bullet says a dedicated independent circuit, 2.5 or 4 mm² cable, and a fuse of at least 40 A.
This Mulcort offers a simple 3 kW route to point-of-use heating and claims a UK 3-pin plug, LED control and a 28–55°C range. Unlike a 5.5 or 6 kW claim, 3 kW sits around the power normally associated with a 13 A supply, although the actual data plate and instructions still need checking. The listing also names overheat and dry-burn protection and a G1/2 connection. Confidence is limited because there are no UK reviews in the extract to confirm its temperature, flow, plug or durability. The box contents are inconsistent too: one bullet lists a shower kit, while the included-components field names only the manual. It may suit a low-flow basin experiment, but the evidence does not support treating it as a shower package.
Pros
Cons
Best for: A single low-flow hand-wash basin where the delivered plug, data plate and accessories can be checked before fitting
Less suitable: A shower, kitchen bowl, or buyer who wants independently reviewed performance and complete specifications
Specifications
Common questions
Does this Mulcort include a UK plug?
A bullet says it comes with a UK 3-pin plug. No voltage number is printed, and there are no reviews to confirm the plug.
Is a shower head in the box?
One bullet lists a shower head, hose, holder, screws and a manual. The included-components field lists only the user manual.
What temperature range is claimed?
The spec maximum is 55°C. The bullet says 28–55°C. No flow rate is printed.
We compared seven electric tankless listings on amazon.co.uk against public UK sources on hot-water safety, Part P and manufacturer sizing notes. Scores follow the amazon.co.uk star rating where a review line exists. There is no laboratory flow test, and a missing review line is left at zero.
Kilowatts and flow
25%Outlet temperature falls as flow rises. Rules of thumb from Hyco and Stiebel Eltron set the size, then the model table has to agree.
Electrical supply
25%About 3 kW sits near a 13 A BS 1363 plug. Higher claims need a dedicated circuit, and a new circuit is Part P notifiable work.
Job and outlet
20%Hand wash, a bowl, a shower and a bath are different loads. A bath, and two full outlets at once, sit outside this set.
Pressure and control
15%Open-outlet taps, minimum pressure and electronic control decide whether the stated temperature is usable at one outlet.
Listing evidence
15%A data plate and a UK manufacturer sheet outrank a title. Conflicting power, size or box lines, and a missing review count, lower confidence.
Start with the job, not the brand. Hand washing, a washing-up bowl, a shower and a bath are different loads, and a bath is outside these seven amazon.co.uk listings. Then match kilowatts to flow and to the circuit you actually have. A 13 A socket is the wrong place for a 6 kW claim. Read the outlet type and the pressure lines, including places where the bullet and the spec table disagree. Prefer a data plate and a UK manufacturer sheet when the title conflicts with the technical details.
A tankless water heater on the UK market, in this comparison, is an electric instantaneous heater. It warms mains water as it flows and does not hold a cylinder of hot water. Shoppers on amazon.co.uk use one for a cloakroom basin, a remote sink, or, at the top of the power range, a shower where there is no gas. A bath, or two full outlets running together, sits outside the seven listings here. Gas combis and three-phase 400 V heaters are adjacent, not these ASINs.
A 10 litre undersink heater is stored hot water, not an instantaneous unit. It can be the right tool for a washing-up bowl on a 13 A socket, which is why it is not on this table. Do not compare its recovery with a 3 kW inline box as if they were the same product.
About 6 kW is roughly 26 A at 230 V. A listing that asks for a 40 A fuse and then arrives with a 13 A plug has not solved the supply. In this set that conflict shows up in Delousiber reviews. The plug is not proof that the heater is a normal socket appliance.
Three kilowatts can warm a trickle for hand washing. It does not give shower flow, and it does not fill a bath. Opening a second tap and blaming the heater is the same limit: these units usually serve one outlet at a time. Judge the heater on a cold day, not only in warm weather.
Kilowatts against the flow you want is the first technical cut. A tankless water heater stores no reserve, so outlet temperature falls as flow rises. Hyco’s rule of thumb is that temperature rise in degrees Celsius equals kilowatts times 14.3, divided by litres per minute. Stiebel Eltron’s sizing FAQ puts the same idea in outlet terms: kilowatts divided by 2 is about the litres per minute at 38°C, and kilowatts divided by 3 is about the litres per minute at 50°C. Both are rules of thumb.
The supply decides whether the kilowatt figure is usable in a UK home. Mains voltage is 230 V and a normal socket is a 13 A BS 1363 plug, the region of about 3 kW. A 6 kW claim is about 26 A. The Delousiber and laloohome bullets ask for a dedicated circuit and a fuse of at least 40 A. UK reviews of the Delousiber say a regular plug was fitted anyway, which does not make a 6 kW load safe on that plug.
Three typical situations, each with a recommendation from this comparison.
You are replacing an immersion that only fed taps, and a high-current circuit is acceptable. UK reviews of the Stiebel Eltron DCE-X describe stable basin hot water and, in some installs, a shower. It is not a bath filler and it does not plug into a 13 A socket.
The basin is far from the combi and you only need short draws. The ThermoMate ET055 is the reviewed 5.5 kW option for that job, once a breaker of about 25 A or higher is in place. It is not a kitchen-bowl heater in the critical reviews.
You have a cold feed and want a tap that heats at the sink, with a slower flow. The TopSer BS-18DC-3 Pro is the electric-tap listing in this set. UK reviews also report leaks and shocks, so stop using it at the first fault.
On this page the top pick is the Stiebel Eltron DCE-X 10/12 if you can fit a high-current circuit and you need a basin or, in some UK installs, a shower. It is not a bath heater and it is not a 13 A appliance. The best value for a cloakroom hand wash is the ThermoMate ET055, at £109.74 with 248 amazon.co.uk reviews, provided a circuit of about 25 A is acceptable and a trickle of warm water is enough. The cheaper 3 kW and 6 kW marketplace units stay limited by flow, missing reviews, or a plug that does not match the wattage.
Stiebel Eltron DCE-X 10/12
Electronic control, a stated 5 L/min and 55°C, and UK reviews of stable basin hot water where a high-current circuit exists.
ThermoMate ET055 5.5 kW
The reviewed hand-wash option at £109.74, with 4.0 from 248 amazon.co.uk reviews, once a 25 A circuit is in place.
Editorial
Peter F. is the editor for DIY & tools at productscompared.co.uk. Comparisons in this category are checked against amazon.co.uk listings, review evidence and public UK sources.
Guides on what to look for, how to use a product, and common mistakes.
Public UK sources used for this comparison, last checked on 17 October 2026.
This article contains affiliate links. If you buy through them, we may earn a commission at no extra cost to you. Prices and review counts come from amazon.co.uk listings and public UK sources, not from a laboratory test.
