The best 300 l water heaters in the UK 2023

A water heater remains an indispensable element to ensure domestic comfort. Choosing a 300l water heater is advantageous, because not only does it cover your hot water needs, but more importantly, it is easy to use, install, powerful and with a beautiful design. This article will shed more light on the subject so that you can make the right choice that best suits your own needs.

THERMOR Steatis 300L 1

Editor's Choice

THERMOR Steatis 300L

The best 300 l water heater

If you are looking for a water heater for a household of 6 people with a soapstone resistance that is protected from limescale, the THERMOR Steatis 300 L is the appliance for you!

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This Thermor Steatis 300L water heater, as its name indicates, is equipped with a steatite resistance. This means that it can be changed without the need to drain the water. It can provide hot water to a household of 5 people and more. Very generous in capacity given its narrow volume format, it also provides hot water very quickly. With this Thermor water heater, the need for hot water is guaranteed.

Moreover, it is a very safe and resistant device, very hygienic, fights against limescale, which also guarantees clean and hygienic hot water in the whole house. This water heater has a vitrified enamel inner lining and an enamelled heater body. In addition to the beautiful design and new internal compositions, this device also has the basic features of a boiler such as temperature settings, economic mode through the hydraulic system. This means that you can control it with precision.

THERMOR Vertical Armored Base 2

Best cheapest

THERMOR Vertical Armored Base

The best entry-level 300 l water heater

THERMOR's 300 liter vertical water heater with an armoured base will save you money in the long run, and even save you money if you choose a low energy efficiency model.

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Since then and even with the innovation of this water heater THERMOR vertical base armored has been more and more respectful towards the environment thanks to its excellent energy efficiency, significantly improved compared to older models, with 8% less energy than the latter. This appliance does not lack quality and its longevity and performance are particularly appreciated.

Not to mention that it complies with strict hygiene standards and guarantees pure hot water. Why is this so? Because it has an inner coating of vitrified enamel with a high quartz content. More precisely, thanks to the technology provided by THERMOR, the water heater is well suited for aggressive, highly mineralized and desalinated water. The ceramic heating element of this water heater is protected by an enamelled steel sleeve, which guarantees a large heat exchange surface and reduces limescale deposits.

ATLANTIC 154330 300L 3

Best high end

ATLANTIC 154330 300L

The best high-end 300 l water heater

The ATLANTIC 154330 Zeneo is a quiet but powerful high capacity water heater. It meets all indoor installation requirements. It is ideal for the whole family

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It is a very innovative but at the same time very recommended device. This water heater is very easy to install and comes in three models (vertical, vertical accelerated, floor standing) plus 14 versions. Its efficiency and durability are optimized by the use of an ohmic resistor. And Zeneo's unique ACI Hybrid technology provides dynamic corrosion protection for lasting quality.

This heater provides up to 20% energy savings thanks to the electronic thermostat and the high-precision bulb thermostat with built-in safety. That means you won't have to worry about increasing your bill at home. In addition, with respect to this safety, it follows the European standards for electrical safety and user protection. Not to mention that it is an ecological water heater.

ATLANTIC 022130 300L 4

Excellent choice

ATLANTIC 022130 300L

The best choice water heater

To never run out of hot water, the ATLANTIC 022130 300L water heater offers a wide choice of capacities, shapes, designs and technologies while meeting the requirements of your home's interior.

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With such a large capacity and narrow volume, this unit easily fits into a variety of spaces. It's true that it's a floor standing water heater that features an indicator light for the ACI and heating system, but it has a side connection that makes it an easy replacement for wall mounted horizontal models. Aside from these smart features, and the fact that it generates hot water very quickly, it also has magnesium anode protection.

This appliance is easy to maintain without the need to drain, because inside is installed a ceramic heating element in an enamelled sleeve, so it limits the scale deposits. The presence of new technologies in this heater, such as the new generation thermostat, has made it silent and prolongs the life of the device. The water tank is in line with glass with titanium and copper for the protection of the appliances.

Buying guide • November 2023

Best 300l water heater

Any specific needs?

The best 300 l water heater

The best entry-level 300 l water heater

The best high-end 300 l water heater

The best choice water heater

Your guide : Samuel

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Comparison table of the best 300 l water heaters

THE BEST LESS EXPENSIVE Top of the line Excellent
THERMOR Steatis 300L 5
THERMOR Vertical Armored Base 6
ATLANTIC 154330 300L 7
ATLANTIC 022130 300L 8
THERMOR Steatis 300L
THERMOR Vertical Armored Base
ATLANTIC 154330 300L
ATLANTIC 022130 300L
If you are looking for a water heater for a household of 6 people with a soapstone resistance that is protected from limescale, the THERMOR Steatis 300 L is the appliance for you!
THERMOR's 300 liter vertical water heater with an armoured base will save you money in the long run, and even save you money if you choose a low energy efficiency model.
The ATLANTIC 154330 Zeneo is a quiet but powerful high capacity water heater. It meets all indoor installation requirements. It is ideal for the whole family
To never run out of hot water, the ATLANTIC 022130 300L water heater offers a wide choice of capacities, shapes, designs and technologies while meeting the requirements of your home's interior.

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Report an error, request the addition of a feature to the table, or suggest another product. Thank you for your kindness!

Buying guide - 300l water heater

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How to choose your 300l water heater

Before choosing your water heater, it is essential to ask yourself questions about the choice to be made. Even if it is a first installation or a replacement, because choosing a water heater for the house will ensure comfort and allows you to control your energy consumption. For this, the choice is made :

#1 - According to the price

The prices of water heaters vary on the market. The cheapest is 155 euros. This is the minimum price. For the average price, it is 1603 euros. And finally, the most expensive on the market is 3050 euros. So the choice here depends on your budget.

#2 - Depending on the energy used

There are different types of energy in water heaters, such as electricity, natural gas, propane, oil, solar energy and many other energy sources. But the typical size for a use varies from 75 to 400 liters or 20 to 100 US gallons. So for the choice it is necessary to determine it well which type of energy is ideal for your house.

#3 - Depending on your hot water needs

Savoring correctly its needs in hot water is paramount, because it helps you to direct you towards the good water heater. The capacity of a water heater depends on the makeup of your family. And a unit that is too large, can consume energy and a unit that is too small, is not going to cover your needs. If it's just one person living in a house, he can make do with a 50L water heater so it can be a mini water heater. But for a family of 4 or more people, the choice should be for a 200 L water heater. And the ideal for a house or an apartment is the traditional water heater called cumulus or storage water heater, because they are practical and consume the least energy.

#4 - The help of a professional

Seeking the advice of a professional is essential to not choose the wrong water tank that does not even fit your home. Why? Because professionals know how to estimate your home's consumption as closely as possible. And this, according to the number of people and your habits for bathing or showering. They can also check if the configuration of your home is adapted to the type of water heater you wish to purchase. He can also advise you on the installation.

#5 - The choice of renewable energy

Renewable energy water heaters are economical to use, as the initial investment pays for itself over the years. They are also an eco-responsible management and a real capital gain in case of resale of the property. But they are expensive on the market, but very ecological. So if you have a bigger budget, you can go for this kind of water heater.

The heater's resistance can be damaged prematurely

Yes, in fact, if you live in an area where the water is very hard, the resistance can be put to a severe test and no longer heat the water properly. You should therefore choose a product with a soapstone heater to prevent this from happening. The water heater with soapstone resistance is composed of an enamelled steel sheath that protects the resistance from the aggressions of water and thus prolongs the life of the equipment. You can also have a water softener installed in the water circuit to supply your water heater and ensure its durability.

Water heater or gas boiler

Water heaters

The water heater is a domestic or industrial equipment which is used to heat water using an energy source. Its advantage, the water heater whether electric or other, is that it is at an affordable price, for the electric water heater the price varies from 200 to 1500 euros. It is light and very practical to heat your home. And it has a storage capacity between 100 and 300 L. Its disadvantage is that its performance is poor, and it is prohibited in new houses. But also, most water heaters take longer to bring the water to the right temperature, plus the storage is heated only once a day and it takes about 8 hours to have hot water ready to use.

Gas boiler

The advantage of the gas boiler is that the production of hot water by accumulation is very important. It requires a higher initial investment, but it pays for itself very quickly thanks to its performance. Moreover, with the gas boiler, hot water is produced continuously. It has a tank where the hot water is stored at least 40 litres. It also provides excellent comfort as the water is available anywhere and anytime. Its disadvantage is that gas reserves are far from being infinite, so it is a particularly polluting energy. Moreover, its maintenance requires a certain investment which can quickly become expensive in the long term.


Although both of these devices have their own advantages and disadvantages, it is obvious that if you want to opt for a water heater, it is very convenient, as it has a higher water storage capacity compared to the boiler. On the other hand, if you want to have continuous hot water in your home, opt for gas boilers. That way you always have water available and ready to use.


Save your consumption

Did you know that? If the temperature is too high, you will use more electricity and water, and you can also get burned. Therefore, it is important to set the temperature of your water heater properly, because very hot water can burn your skin. It is possible to set your water heater to 50°C which will be sufficient for most uses.

Insulate hot water circulation pipes


limit heat loss, it is therefore advisable to insulate the hot water pipes in your home. This is very useful when your water tank is located in unheated spaces, in the basement for example.

Maintain your equipment


should not forget to check and clean your water heater every year as this will prevent the formation of limescale which can greatly reduce the flow of hot water, and extend the life of your appliance


Repair leaks

It is

very simple to check if you have water leaks or not in your home. To do this, turn off all water consuming appliances like dishwasher, washing machine ect.. Then, turn off all your taps properly and finally, if you see that your water meter is running, there is a leak somewhere.

Wash at low temperature


setting your machines to low temperatures i.e. 30°C or 40°C, your laundry will keep its cleanliness. And this will be accentuated if you use quality dishes.


What is the best 300 l water heater?

The best 300L water heater depends on your needs and budget. Read our buying guide to find out which products are the best at the moment.

What is the average hot water consumption?

For a standard profile, it is necessary to count 50 liters on average per day and per person. But for a bath, the consumption of hot water is between 120 and 140 litres and this at 40°C. For a shower, the consumption is 40°C and this for 40 litres of water only. So for a family of 3 people, the need for hot water is 150 L for a classic or 80 L to save space.

How do I adjust the water heater?

Adjusting your water heater means adjusting its temperature because it allows you to have comfort and a good safety ratio. The ideal temperature is therefore 50°C, if you do it below, there will be a risk of bacteria. And above 60°C there will be a risk of burning. So try to set it to the ideal temperature.

What should I do if the water heater won't turn on?

If your water heater does not turn on anymore, you must first check its electrical supply. Then, you should also check the circuit breaker or fuse dedicated to your hot water tank. So to reset your water heater, you can turn on the breaker or fuse and see if your water heater turns on.

How to drain the water heater?

You should first check that you have turned off the water supply before draining it. You should also make sure that you have a flange gasket to hand, as you will need a new one. To drain your hot water tank, use the safety group and basins. It is advisable to open a hot water tap at the same time, in order to access the inside of the tank when it is empty, so you must also unscrew the flange.


Note: Below are some of the sources we have consulted in writing this article. Links to other sites are not continuously updated. It is therefore possible that a link may not be found. Please use a search engine to find the desired information.
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March 2022 : Translation of this buying guide from our partner

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Our selection
THERMOR Steatis 300L 9
THERMOR Steatis 300L
THERMOR Vertical Armored Base 10
THERMOR Vertical Armored Base
ATLANTIC 154330 300L 11
ATLANTIC 154330 300L
ATLANTIC 022130 300L 12
ATLANTIC 022130 300L


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