System boilers are a more traditional type of boiler, which require a separate hot water cylinder to store hot water. They are ideal for homes with more than one bathroom or higher hot water demands, as they can supply hot water to multiple outlets at the same time. They are also suitable for larger homes with multiple floors and radiators. Unlike heat only boilers, all of the components that would usually be found external to the boiler (pumps, valves etc) are inside a system boiler. This means more of the heating system is covered by the boiler manufacturer’s warranty. System boilers require good incoming water pressure and good internal flow rates to operate at their stated capacity.