System Boilers

A system boiler is a good option if your home has 2 or more bathrooms and you don't have space in your attic for a water tank.

You should also consider whether a combi boiler or a conventional boiler would be better suited for your home.

Complete the form at the top of this page to get a free quote from a trusted local boiler installer.

What is a system boiler?

A system boiler has the main heating and hot water components built into the boiler and requires a separate sealed cylinder (or tank) for storing hot water. System boilers pump hot water to the radiators and the hot water tank.

As most of the heating and hot water components are contained inside a system boiler, installation tends to be easier and more efficient, than with a conventional boiler.

System boilers also take up less space than a conventional boiler because you don’t need a water tank in your loft.

See also:

  • How much does a system boiler cost?

  • How do system boilers work?

    The diagram below explains how a system boiler works in your home:

    system boiler

    Is a system boiler right for me?

    System boilers are great if you are looking for a boiler that is:

    + Ideal for homes with two or more bathroom
    + Doesn’t require a water tank in the loft
    + Economical to run

    The downsides of having a system boiler heating system include:

    - Hot water isn’t instantly available
    - Hot water can run out

    What alternatives are there to a system boiler?

    Alternatively, you can install either a combi boiler or a conventional boiler. The boiler system that works best for your home will depend on both your heating requirements and the size of your home.

    For example, combi boilers are cost and energy efficient and great for smaller homes; they save space and are ideal if you only have one bathroom. Conventional boilers, however, are ideal if your home has two bathrooms and are a good option if you already have a traditional heating and hot water system.

    Click here to find out which boiler is best for you, or read on to find out more about conventional boilers.

    Who manufactures system boilers?

    System boilers are manufactured mainly by the following companies, who are trusted names within the industry:

    Baxi has been manufacturing boilers in the UK for 150 years. They produce mid range boilers, which are fairly reliable and very efficient. All new Baxi boilers are endorsed by the Energy Saving Trust™ and in 2015 Baxi updated Greenstar gas boiler range in line with new energy efficient standards. Baxi boilers tend to cost less to buy and install than some other boiler brands, including Worcester Bosch and Vaillant.

    Worcester Bosch
    Worcestor Bosch are one of the market leading boiler brands in the UK and are generally regarded as high quality, efficient boilers. In 2015 Worcestor Bosch updated its Greenstar gas boiler range in line with new energy efficient standards and this range has won the Which? Best Buy award for six years running (2010 - 2015). Worcestor Bosch boilers tend to incur a premium price, but could work out as good value for money in the long run.

    What are the leading system boilers?

    The following table shows the leading system boilers, based on central heating output and the average price with installation:


    Product name


    Max. central heating output (kW)

    Average price with installation*

    Worcester Bosch
    Greenstar i System

    See also:

    Conventional Boiler guide

    Combi boiler guide

    Boiler finance guide

    See How Much a System Boiler Would
    Cost for Your Home

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