Choosing a new boiler

Whether you need a new boiler, or you want to upgrade your existing one, deciding which type is right for your household may seem like a daunting task. However, with this easy to follow guide you can discover what you need to know to be able to choose a new boiler with confidence.

Where do I start?

The first and most important thing to think about is the hot water and heating demand in your household. For example, do you have a small property and a low demand for hot water and heat, or do you have a busy household with multiple bathrooms and more than one shower in operation at the same time? Also think about whether you have built an extension or added more bathrooms and since the previous boiler was installed, or whether you are planning future extensions or room conversions, as these scenarios could mean larger output requirements.

Having taken all of this into account you will find that certain types of boilers will meet your requirements better than others, thereby enabling you to narrow down your final choice.

What boiler do I need?

What are the main types of boilers available?

If you are connected to mains gas – as most UK homes are – then you have a choice of three main types of gas-condensing boiler. Below is an explanation of how each one works and the type of household situation they suit best.

Combination Boilers (Combis)

  • Combi boilers heat up water on demand and do not require a bulky water tank or a hot water cylinder
  • They are considered the best choice for small to medium size properties with average hot water demands
  • Energy is not wasted by heating water that may not be used, thereby reducing your heating bills and your carbon footprint
  • They are quick and easy to install
  • They are the most popular type of boiler in the UK

Regular Boilers

  • Regular boilers - also called heat-only or traditional boilers - provide central heating and hot water using an airing cupboard storage cylinder, and also require a cold-water storage tank plus an expansion tank in the loft.
  • Featuring in most older heating systems in the UK they are slightly less efficient than combis, but they are the ‘go-to’ choice for large homes with a high demand for hot water or multiple bathrooms, or for situations that already have a traditional heating and hot water system in place
  • On the downside they tend to be more expensive to install and take up more space

System Boilers

  • System boilers provide central heating and hot water using an airing cupboard storage cylinder but, unlike regular boilers, they do not rely on water supplied by a cold-water storage tank in the loft.
  • The hot water in the storage cylinder is always topped up ensuring hot water is always available which makes these boilers well suited to large, multi-bathroom properties with high hot water demands.
  • As well as saving space they are also easier to install than conventional boilers as many of the components are built into the boiler

What are the advantages of a system boiler?

When it comes to replacing traditional boilers, often the easiest thing to do is replace like for like but, if you have a water tank in your loft and you wish to free up that space, you can opt to change the cylinder from a vented to an unvented version (which does not require loft tanks), or even convert to a combi boiler. However, you will also need to bear in mind the extra expense of making changes to an existing system.

You can find out more about the different boilers in our range by clicking here: Alpha boiler range. All our domestic boilers feature a stainless steel heat exchanger and come with comprehensive warranties up to 10 years (which can be extended further to up to 13 years when installed with specified accessories).

What are the options if I live off grid?

What if I have above average hot water demands?

For homes that require hot water for long periods or high flow rates even when demand is high, there is yet more choice. Offering a ‘best-of-both worlds’ scenario, FlowSmart from Alpha delivers the energy-saving qualities of a combi and the performance of a conventional boiler. Using approximately 25% less gas than a system boiler and more than matching the hot water performance, FlowSmart enables large households to enjoy the energy efficiency benefits of the combination boiler.

When and why should I upgrade an existing boiler?

If your current boiler is an old model, typically over 15 years old, then replacing it with a modern gas-condensing boiler could help you save money on your energy bill. Heating accounts for approximately 60% of what you spend in a year on energy bills so having a modern, efficient boiler is really important. In addition, it could make your home safer and reduce emissions.

Next steps

We hope this information gives you a clearer understanding of your boiler options but do always have a thorough survey conducted by a qualified Gas Safe engineer. As part of the survey, additional factors will be checked such as the number of radiators you have, your water pressure, the number of bathrooms in your home and the positioning of the current boiler.

Find your nearest installer

Our 'Find my nearest' tool allows you to find a local installer near you. Simply type in your postcode and we'll provide a list of companies. All installers listed on this website have installed our boilers within the last 6 months so are fully up-to-date with our product range and boiler installation procedures.


Easy ways to help you avoid wasting energy and save on your heating bills, without sacrificing home comforts.

Useful information and advice

What you need to know about looking after your boiler as well as guidance on gas safety in your home.

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