A relatively new invention in the field of boilers, the flow boiler produces both hot water and electricity at the same time, making it a versatile tool for both heating your water and powering various electrical appliances around the household. It qualifies as a type of combined heat and power (CHP) boiler - these have been used in commercial areas with great effect for quite a while, which goes to show that the output of CHP boilers is quite high - high enough to reliably supply a larger area with hot water. One of the biggest benefits of a flow boiler is that it can help you save money in the long-term, even if the initial cost is higher than that of a standard boiler. At the same time, you will require a separate hot water tank in order for it to function, so it's definitely not a space-saving option.