Do Electric Boilers Need a Water Tank?

If you are considering buying an electric boiler, you might be wondering whether you will need a water tank as well. The answer is, it depends on the type of electric boiler you buy.

In this guide, we will explain the differences and help you to understand whether your electric boiler will need a water tank or not?

Do electric boilers need a water tank

One of the big attractions of a traditional combi boiler is the absence of a water tank. This not only saves valuable space in a smaller property but it is also one less thing to go wrong.

But in some homes, water tanks are still needed, so what about if you want to install an electric boiler instead of a more traditional gas or oil-powered one?

The short answer is that, like gas and oil boilers, it depends on the type of electric boiler you buy. In this guide, we will explain which electric boilers need a water tank and which don’t, to help you understand what your property will need.

Different Types of Electric Boilers

Just like conventional gas and oil-powered boilers, electric boilers come in a variety of different shapes and sizes to suit different properties. Some of these types of boiler require a water tank and some don’t, so here is a quick run-down of the most common varieties.

  • Direct – A direct electric boiler is the equivalent of a combi boiler. It uses a heating element to heat water on demand and therefore has no need for a hot water tank. This makes it simpler and cheaper to buy and install but does mean that you can’t take advantage of Economy 7 tariffs by heating water overnight for use during the day.
  • Storage – As the name suggests, a storage electric boiler does require a water tank, either within the unit of separately. This type of electric boiler does let you take advantage of cheaper overnight electricity costs to heat and store hot water. But they are also bigger and more expensive.
  • Electric CPSU – A Combined Primary Storage Unit (CPSU) stores a lot of hot water within the boiler to enable it to meet higher demands and provide water at a higher pressure. This type of electric boiler does have a water tank within the unit but is usually only found in commercial units.
  • Dry Core Storage – Dry core boilers use cheaper nighttime electricity tariffs to heat bricks. This heat is then released into water during the day to provide hot water and central heating. They work in a similar way to storage heaters.
  • Solar compatible – If you want to power your boiler using energy from solar panels, you can do so, but this type of electric boiler will need a storage tank with an immersion heater.

Which Type of Electric Boiler is Right For You?

Deciding which of these electric boilers is the right type for your property will depend on a variety of different factors.

A direct electric boiler is typically more suited to smaller properties with fewer radiators and less hot water demand. If you have multiple bathrooms and more people using hot water, you will probably need a storage electric boiler to meet your demands.

If you have solar panels or are planning to install them, a solar compatible boiler is a good choice, but you should check with your installation company that you are buying the right-sized boiler before paying up.

Other advantages of choosing an electric boiler

The rules around water tanks with electric boilers are generally much the same as gas or oil-powered boilers. So, what other advantages are there to choosing an electric boiler?

Here is a run-down of the most notable advantages:

  • Low Installation costs – While an electric boiler costs roughly the same as a gas or oil-powered boiler, it is generally much easier to install. This means the installation costs are much lower saving you money.
  • Reliability – Electric boilers are much simpler and the absence of a physical fuel means there is far less that can go wrong. As a result, they tend to be much more reliable and cost you less in maintenance and repair.
  • Low Carbon Emissions – Electric boilers have an extremely low carbon footprint meaning your property will be much greener.
  • Energy Efficiency – Electric boilers have an energy efficiency rating of around 99%. This means you waste less fuel and save money.
  • No Noise – Electric boilers make little or no noise which is great, especially in a smaller property.
  • Location – Electric boilers don’t need a flue to get rid of poisonous gases. This means you can install them anywhere in your property.
  • Size – Fewer components mean electric boilers can be much smaller than gas or oil boilers, especially if you choose a type that doesn’t need a water tank. As a result, you can install them in any small cupboard, under the stairs, or anywhere else convenient.

The main disadvantage of an electric boiler

The key disadvantage of choosing an electric boiler are the running costs.

Electricity is generally between two and three times as expensive as gas or oil. But as we have explained in our guide on the running costs of an electric boiler, this doesn’t necessarily mean an electric boiler costs two or three times as much to run.

There are various costs to running a gas or oil boiler that you don’t have with an electric boiler and, crucially, it also consumes around half as much ‘fuel’ as a gas or oil-powered boiler. This makes the costs broadly comparable overall, or slightly higher at worst.


Some electric boilers do need a water tank and some don’t. Some will have a built-in water tank and others need a separate one. It all depends on the type of boiler you choose.

In this guide, we have explained the different types of electric boiler and identified which require a water tank and which don’t.

We have also highlighted the key advantages of choosing an electric boiler and the one major downside.

Have you ever had an electric boiler in your home? Did it have a water tank? How did it work for you?

Do you have any tips or advice for our readers about electric boilers hat we haven’t touched on in this guide? Do you have any question about electric boilers and water tanks that we haven’t answered in this guide?

If so, do share them with us by leaving a comment in the box at the bottom of this page. We will try to respond to all comments as fast as we can.



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