Electric combi boilers work in a similar fashion to gas combi boilers, only they run directly on electricity as opposed to natural gas. Consequently, electric boilers are becoming increasingly popular for new build flats or smaller properties that do not have a mains gas supply. As well as being exceptionally reliable, they are highly efficient with rates around 99% compared to 89-95% for most gas boilers. With no moving parts, electric combi storage boilers are incredibly quiet and do not require annual servicing, keeping maintenance at a minimum. Despite being larger than a standard electric flow boiler, the electric storage boiler makes use of an additional built-in tank, that is both space saving and provides powerful mains pressure for showering and bathing.