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Instant Hot Water Heater: The Best Instant Water Heater for 2023

Hot water is a cornerstone of modern comfort, but choosing the right instant water heater is anything but a simple task. With so many units covering so many niches across the market, how can you possibly make a decisive choice?

Instant water heater

Today, we present a range of instant heaters that you can use under the sink, on the wall, or even outdoors.

Towards the end of the page, you’ll also find a short buyer’s guide to help you narrow down your comparison shopping beyond our recommendations.

8 Best Instant Water Heater Models in the UK  

Our market research indicates that the following instant hot water heater models offer the best value for money. Each fills a different niche, so go through the full list to find the best unit for your needs.

1. ATC 5L Instant Water Heater (2kW, Undersink)

Under sink Water Heater by ATC 5L 2kW

What this instant water heater from ATC lacks in verve, it makes up for in pure functionality. It features a respectable 5 litre tank running through 2,000W of robust heating for hot water on demand. What’s more, the ATC supports two sinks–perfect for spa-style bathrooms or dual kitchen sinks.

While categorized as an undersink unit, you can just as easily mount the ATC 5L on your wall. The tank is insulated with high-density polyurethane foam, which does a great job of retaining heat and shrinking your monthly power bill. Combined with an external thermostat for fine temperature control, and you’ve got a durable, highly efficient instantaneous water heater that occupies any role your home requires.

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2. BuoQua 15L Electric Instant Water Heater (1.5kW, Undersink)

BuoQua 15L Electric Water Heater 1500W Instant Water Heater Under Sink

If you’re looking for a large-capacity electric instantaneous water heater that won’t break the bank, the BuoQua is well worth your consideration. We especially recommend this unit for households with many people sharing a sink. 15 litres is positively cavernous, and equal to the task of prolonged usage without running out of hot water.

What’s more, BuoQua has clearly built this unit to last–with robust, corrosion-resistant materials and IPX4 splash-resistant rating. The electrical and water systems are well separated for safety, and the 15L heater features high-efficiency piping to prevent heat loss. Dial in the perfect temperature between 30–70℃ and you’ve got hot water on demand for the whole family, even throughout the coldest months.

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3. Stiebel Eltron DHC-E12 Instantaneous Water Heater (12kW, Oversink)

Stiebel Eltron DHC-E12 Electronic Instantaneous Water Heater

If you’re looking for a premium investment, we recommend the Stiebel Eltron DHC-E12 instantaneous water heater. A true workhorse, the DHC-E12 features a whopping 12,000W of power, which makes a storage tank and venting entirely unnecessary. This allows for more flexible installation; its sleek, single-unit design takes up a non-offensive amount of space in your kitchen or bathroom.

A single, easy-to-read dial belies advanced technology underneath, which uses a microprocessor to ensure output at exactly the temperature you specify. While you can bring the water up to scalding to comply with health advisories, normal operation ensures instant, but comfortable delivery of hot water on demand.

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4. Triton T30i Handwash Electric Tankless Water Heater (3kW, Oversink)

Triton T30i 3kW Handwash

If you’ve got a room where hot water delivery would otherwise be impossible, try the Triton T30i Handwash electric tankless water heater. This compact design fits right above your sink, acting as both heater and tap for seamless functionality. Indeed, Triton has prioritised usability — this unit sports a single numbered knob, which simply turns the unit on directly to the temperature you specify, or off. With 3,000W of power, you won’t have to worry about waiting around to get hot water on demand, either.

Not enough? You can easily adjust the direction of the stream with the T30i’s modular swivel head, which comes in 200mm and 300mm variants. Combined with easy installation that doesn’t require a plumber, and you have a flexible instant hot water heater that delivers respectable performance in hard-to-heat areas of the home or workshop. 

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5. Hyco Handy Flow HF05LQ (2kW, Oversink)

Water Heater Oversink 5 Litre Tank Handy Flow Hyco HF05LQ

The Hyco Handy Flow is just as its name suggests–a handy way to install an instant hot water heater almost anywhere. Billed for use in portable buildings, offices, garages, and workshops, it can easily fill residential purposes as well, such as sheds and guesthouses. The only restrictions you’ll face with the HF05LQ is the need for a plumber to install it to account for venting. Thankfully, it’ll be an easy, cheap job.

On its own merits, the HF05FLQ features robust 2,000W heating, easy external controls, frost protection, and a neon indicator light. We also love its slim line design, at just 180mm deep. Despite its diminutive profile, durability won’t be an issue, with high-impact plastic casing and an IP24 splash-proof rating.

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6. Camplux BW158BC 6L Instant Gas Water Heater (12kW, Portable)

Camplux BW158BC 6L Instant Gas Water Heater with Rain Cap

Billed as providing “endless hot water”, the Camplux BW158BC is a tankless, instant hot water heater that offers an astounding 12kW of gas-powered, tankless heating to make good on their claim. What’s more, this massively capable unit is portable, with D-battery operation that can be used (fitting to the brand’s name) even whilst out camping. If that prospect makes you somewhat nervous–keep in mind that the BW158BC can get 180 days of use out of two batteries (note that you still need propane to run this heater).

The BW158BC’s design is ultimately user-friendly, with simple water and heat knobs and an LED temperature display. There’s also a 37mbar CE gas regulator, which is conveniently compatible with any propane tank. With 6 litres of heating capacity, you’ll enjoy the same level of comfort outdoors as you would showering at home. Keep in mind, though, that these instant water heaters are designed for the outdoors.

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7. Camplux BW264C 10L Gas Water Heater (20kW, Portable)

Camplux BW264C Tankless Gas Water Heater with Rain Cap

Similar to its little brother, the Camplux BW246C instant water heater is robust, portable, and offers even more power. It still requires two D batteries to operate, but produces 20,000W of power when attached to virtually any type of propane tank. It also features the same robust, weather-proof design, allowing it to fit virtually any application. Both units also come in your choice of black (BWxxxBC) or white (BWxxxC).

The biggest differences between Camplux’s series are the capacity and weight. The BW264C can heat up to 10 litres per minute, which is enough for almost any activity with high demand for hot water. On the flip side, the increased output means that the BW264C is slightly less portable, at 11.1 vs. 7.34 kg. There is a moderate increase in price, too, so we recommend you choose the best size for your needs to avoid over-payment or under-performance.

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8. HEEPDD Mini Water Heater (5.5kW, Wall-mounted)

Mini Water Heater, 5500W Electric Instant Water Heater Tankless Shower Hot Water System for Bathroom Kitchen Washing

Last but not least is the aptly named Mini Water Heater from HEEPDD. Don’t let its size fool you–this small water heater is quite suitable for showers and sinks in most homes. Boasting 5500W of electric power, you’ll get your desired water temperature in 5 seconds or less. Like other top-tier instantaneous water heaters, it features an easy-to-read LCD display and simple temperature controls with adjustments between 30-55°C. And, being electric, this on demand water heater is highly efficient, converting most of the electricity it uses into heat.

The HEEPDD Mini is easily to install, with a universal G½” water pipe connector, and doesn’t require a plumber. You can rest easy knowing that the Mini features robust safety protections. These include triple-layer hydroelectric isolation, a waterproof motherboard, and anti-dry protection.

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Buyer’s Guide to Choosing an Instant Hot Water Heater

We’ve given you a nice assortment of the best instantaneous water heater models on the market, but if you’d like to continue with your own market research, keep the following factors in mind:

Best instant hot water heater

Match the Heater to the Application

As you can see in our list above, not all water heaters are intended to fill the same purpose. You wouldn’t, for example, choose a small water heater for taps to power your hot showers in the morning. Neither would you wish for an industrial-scale, wall-mounted, tanked heater on a camping trip.

It’s not just a matter of convenience either; picking the right instant water heaters for the job ensures lower power bills, better safety, and more comfortable warming.

Be Aware of Differing Capacities Between Similar Units

You might look at product listings and think “well, these two heaters look virtually identical. How should I choose between them?” Besides colour differences, many brands group sister units together in a single listing, which may vary greatly in their capacity.

Capacity, by the way, measures how much hot water is produced per minute. This unit of measure is used for both tank-equipped and tankless heaters, so don’t confuse it for how much water your heater will physically store.

Understand Safety Features

As with any device which holds heating as a primary function, all instant water heaters should have failsafes to guard against component failure or misuse. For example, anti-dry protection will shut your unit off when there is no water inside it. After all, water is itself a heat sink, and in its absence there will be nothing to stop your unit from overheating.

You’ll also want to make sure that your electronics are well-isolated from the water, otherwise you run the risk of shorting out, electrocution, or fire. If your instant hot water heater runs on gas, make sure your unit has freeze protection, a cut-off fuse, limiter switches, and adequate venting.

In all cases, you want an instantaneous water heater which boasts superior material durability, and adequate waterproofing to guard against splashes from normal use.

Tankless vs. Tank Storage Water Heaters

A tankless instant hot water heater uses high-powered heating elements to infuse cold water with warmth as it passes through, thus supplying hot water on demand.

Conversely, tank storage units keep hot water reserved in a massive tank, to be drawn upon as needed.

Besides the obvious difference in space required, tankless heaters are typically more energy efficient. This is because there’s no loss of heat from water sitting around unused in a tank. That said, tank storage heaters tend to be cheaper upfront, and require little in the way of expensive maintenance long-term.

Tankless heaters are by definition more portable, with some models designed specifically for use on the go. Whether you’re remodelling your home, building an add-on, or simply need to bring hot water to a standalone workshop with only basic plumbing, a tankless heater will give you the flexibility to get hot water on demand anywhere you need it.

ALTERNATIVE: The best instant hot water dispensers


We’ve covered a lot of ground in this article. But hopefully, you should have a better idea of what sorts of instant hot water heaters are out there–and which might best serve your purposes. Our reviews contain undersink, tankless, oversink, and shower-ready units, some fix and some portable. In any case, each is ready to provide quick access to warm, comforting water any time of year.

What are you looking for in an instant hot water heater? Do any of our recommendations appeal to you? Leave us a comment below.

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