System Boilers

System boiler or a combi boiler?

A combi or ‘combination’ boiler is responsible for providing both your heating and hot water within a single, compact unit. They are often a good choice for flats and family homes, especially where space limitations mean that it is not possible to accommodate a header tank or separate hot water cylinder.

A system boiler, in contrast, features a separate cylinder for storing hot water. Although the major heating and hot water system components are built into the boiler, the hot water is stored in the cylinder. This means that a constant supply of hot water can be provided to a large number of taps and showers at the same time. This makes it the ideal choice for a home with multiple bathrooms.

How it works

In a system boiler, cold water enters the boiler directly from the mains supply. The water is heated via a heat exchanger, which transfers energy from the gas jets to the water. Once heated, the water is pumped to the hot water cylinder, where it is stored until required. Because there is a large reservoir of hot water always available, a steady supply can be maintained even if multiple taps or showers are in use.

How much space does a system boiler need?

One of the most important considerations when considering a system boiler is whether or not you have sufficient space. If your house has been built with an airing cupboard, this can be the ideal place to house the hot water cylinder - but be aware that you will lose the use of this space as a storage space.