A system boiler heats your central heating system directly and produces hot water for your cylinder. Although both system boilers and regular boilers work on the principle of stored hot water, a system boiler is different in two important ways. Firstly, many of the components of the heating and hot water system are built into the boiler itself – making it quicker and easier to install. Secondly, it doesn’t need a feed and expansion tank in the loft. Mr Central Heating stocks a wide range of Worcester Bosch Greenstar system boilers in varying outputs to meet your needs.