Boiler Replacement

Storage Combi Boiler

There is lots to think about when you are planning to install or replace a boiler. You need to take into consideration the space you have, how much hot water you use, and the type of system that’s right for you.

If you use a lot of hot water but have limited space, a storage boiler could be the perfect solution.

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What is a normal combi boiler?

A combi boiler is a system that combines both a hot water and central heating system in the same unit. Hence the name, ‘combination boiler’. It is a very common boiler type as it is highly efficient, and does not need a water storage tank.

The water is heated instantly via the mains, so the pressure is generally good, and water becomes hot very quickly. The main benefits of a combi boiler system are:

  • They are compact, so suit smaller homes
  • They are better for the environment, as you do not have to wait for the water to heat up
  • They are less expensive to repair
  • There’s no waiting around for a tank to refill

What is a storage combi boiler?

A storage combi boiler is similar to a standard combi boiler; however it has a hot water cylinder housed inside the boiler unit.

Storage combi boilers combine the benefits of a combi boiler and system boiler all in one.

They are perfect for smaller homes or apartments that have minimal space, but a high demand for hot water.

Is extra storage necessary for a combi boiler?

One of the main benefits of a storage combi boiler, is that it does not require a hot water storage tank. You can install a storage boiler in your home, without the need to add extra storage or take up valuable space.

Although bigger than a standard combi boiler, they are relatively compact and will usually fit in most places in your home.

How does a storage combi boiler work?

  • A storage boiler has a hot water tank inside the unit, which keeps a supply of hot water ready to use.
  • If your home has a high demand for hot water, such as everyone getting ready for work or school at the same time, a storage combi boiler is a great option.

The water tanks are available from around 46 to 170 litres, and can service multiple outlets without compromising on flow rate.

Storage combi boilers will also have a fast re-heat rate, so the tanks will always be ready to provide hot water for your home.

Different fuels for storage combi boilers

There are different ways to power your boiler, and this will depend on where you live and the age of your home.

You can install a storage combi boiler in your home with these fuel types:

Gas: Gas is the most popular fuel and is the cheapest. However you can only use gas if your home is connected to the National Grid.

LPG: LPG is delivered via a separate tank and is used for homes not on the National Grid. The level of gas needs to be monitored so you aren’t left without power.

It is more expensive than gas, and can be more costly to repair and service the tank.

Oil: Oil is more expensive than gas, but is a common alternative if your home is not on the National Grid. Your home will need a separate oil tank, and it will need to be delivered to your home regularly.

Electric: Running your boiler with electricity is a practical option and will mean your boiler is quieter, however it is more expensive than gas.

Benefits of a storage combi boiler

When installing a boiler, it’s important to do your research to ensure the system will be the most beneficial to your lifestyle. If you are considering installing a storage boiler in your home, here are some of the main benefits:

  • Storage combi boilers are very energy efficient
  • They take up less space than a system boiler
  • They are cheaper to install than a system boiler
  • You don’t need a separate water tank in your home
  • Storage combi boilers meet the demand for multiple hot water uses simultaneously
  • They are compatible with solar panels


It is also important to consider the disadvantages of installing a storage combi boiler in your home. Here are a few disadvantages of a storage combi boiler:

  • It is larger than a combi boiler
  • The size of the internal tank will determine the level of hot water you have
  • The bigger the internal hot water storage tank is, the more expensive the boiler will be
  • They are not a common boiler, so you may need to search for an engineer that is familiar with this system

When to install a storage combi boiler

Before you go ahead, you need to ensure the boiler system you choose is a viable option. This will depend on your current system, budget, and preference. A boiler expert will be able to review which type of system is the most suitable for your home.

You could consider installing a storage combi boiler if the below applies to you:

  • You have a small living space.
  • You do not have a loft
  • If your household has a high demand for hot water
  • You use multiple hot water outlets at the same time
  • You do not have enough storage space for a separate water tank.

Storage combi boiler vs system boiler

Storage combi boilers are less popular than system boilers, which are very common in UK homes.

Despite this, storage combi boilers are becoming more common, as they are a practical and reliable solution for many households. But what are the differences?

  • A system boiler will be more expensive to repair as there are more parts
  • A System boiler requires a water storage tank
  • Installing a storage combi boiler is quicker and cheaper
  • A system boiler will take up more space in your home
  • A storage combi boiler can meet a higher demand for hot water
  • A storage combi boiler will be more expensive to repair, as there are more parts.

Examples of storage combi boilers

What are the best combi boilers from reputable brands?

Vaillant ecoTEC Plus

This boiler is hand built in the UK with 2 stage frost detection. It is an A -rated system that delivers hot water in just 5 seconds.

It comes with a 5 year warranty and is very energy efficient.

The average price of this system is £1,600.

Glow Worm Energy 35 Store Combi Boiler

This system has two highly insulated 21 litre integrated tanks that reduce heat loss. It will deliver hot water quickly and conveniently. It is LPG compatible and costs around £1,700.

It is very energy efficient, has a re-heat time of less than 5 minutes, and has a 7 year warranty.

The average price of this Glow Worm Energy 35 is £1,600.

Viessmann 111-W

This is a high performance boiler, suitable for a family home. The Viessmann 111W has a 46 litre tank, that can fill a standard bath in just 8 minutes.

It has a simple control system and an optional app available to control your heating on the go.

The Viessmann storage combi boiler costs an average of £1,700.

Worcester Greenstar Highflow

This boiler is floor standing, and is designed with multi-bathroom properties in mind. It has built-in frost protection. It comes with a 5 year warranty and is simple to operate.

A Worcester Greenstar Highflow will cost around £2,050

Get quotes from boiler installers

You will need to get in touch with a local boiler installer, to ensure your boiler is fitted safely and professionally. They will use their specialist knowledge to inform you which boiler system will be best for your home.

Check that your gas safe engineer is familiar with storage combi boilers before you go ahead.

Get in touch with local companies today, who will give you a quote on your storage combi boiler installation.

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