Choosing the right boiler type: combi, system, or regular?

Choosing the right boiler type: combi, system, or regular?

Finding the right boiler for your home can be tricky, there are lots to choose from. That’s why we’ve made this quick and easy guide to help you narrow down your options. There are three different types of boiler: combi, system, and regular. We’ve identified the key features of each and created a simple checklist to help you identify which is best for you.

What is a combi boiler?

Combi boilers are the smallest heating system, as they don’t need any water storage tanks. They heat water on demand, meaning you will never run out of hot water, but they can struggle with high demand from multiple taps and showers at the same time. They also have no back up if they break down as they don’t use an immersion heater. They use your mains water pressure as they draw directly from your mains supply. However, if you have low mains pressure it can be difficult to improve, as there is no hot water cylinder to use for technology such as power showers. Read our blog on combination boiler.

Combi boilers explained.

Check out this quick video guide to combi boilers and find out if they’re the right choice for your home.

What is a system boiler?

system boiler is a medium sized heating system. It requires a hot water cylinder, which is usually stored in an airing cupboard. The hot water cylinder stores pre-heated water, meaning system boilers can cope with high demand from multiple taps and showers running at the same time. However, once the tank is empty you will need to wait for the boiler to heat more water - especially inconvenient if you enjoy long showers. They also use your mains water pressure, meaning they are not ideal for low pressure areas. Although, they are compatible with power showers and most technology that can help to improve water pressure.

System boilers explained.

Check out our quick video guide and learn if it could be the right boiler type for your home.

What is a regular boiler?

Regular boilers (also known as conventional or heat only boilers) are the largest heating system - requiring a hot water cylinder and a cold water storage tank. These are usually kept in the airing cupboard and the loft, as the cold water tank must be above the hot water cylinder. This is because the system is gravity-fed, meaning it does not rely on your mains water pressure, making it a good option in low pressure areas. Regular boilers also store pre-heated water, so they cope well with high demand, but can run out of hot water. They are also compatible with power showers and other water pressure technology.

Is a regular boiler suitable for your home?

Get answers to this and more with our short video guide.

Which boiler is right for me?

I have:

  • A small to medium sized home.

  • Good mains water pressure.

  • One bathroom (or I rarely use multiple hot taps at once).

A combi is probably the right choice for you. Find out more about combi boilers. I have:

  • A medium to large sized home.

  • Good mains water pressure.

  • Multiple bathrooms (or I often use multiple hot taps at once).

A system boiler is likely a good choice for your home. I have:

  • Storage space in my loft for a water tank.

  • Low mains water pressure.


  • Old pipework that would be damaged by high water pressure.

You would probably benefit from having a regular boiler. Find out more about the different boiler types and check out our full range.

Could you save money with a new boiler?

Heating and hot water make up over half of the average heating bill, so an efficient boiler can make a big difference. Upgrading to a new A-rated boiler could save you up to £475 a year on your fuel bills1. As an E.ON Next customer, enjoy an exclusive £150 discount on a new boiler. Plus, feel confident knowing that your professional installation will be carried out by a Which? Trusted trader at no extra cost. So, don’t wait for the inconvenience of a breakdown, get more out of your energy. Get a quote online.

Relax with boiler cover from HomeServe.

Sometimes things don’t go according to plan. Be ready for the unexpected with boiler cover from HomeServe - there to help you 24/7 in the event of a boiler breakdown. Whether your boiler needs repairing or replacing you’re covered. Plus, with a free boiler service in your first year we can help you spot any problems and keep your boiler ticking along. Want to protect more than just your boiler? HomeServe can provide cover for your heating, electrics, and plumbing too.

Feel the Community power.

The E.ON Next Community is a space for customers just like you, to share experiences and offer advice. Find support or suggest your own energy topics, plus get involved in discussions on the latest energy news.

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1 An average household could save up to £475 on their annual gas bill. Savings information for boilers in the UK provided by the Energy Saving Trust, based on a detached house with a boiler rating of G.

Published 03/08/2023