: This is not a "type" like the ones above, but rather a feature. Modern boilers are required to be condensing , meaning they capture and reuse heat that would otherwise escape through the flue, significantly lowering energy bills. Fuel Types : Gas : The most common and typically the cheapest to run.

: Ideal for homes without access to a gas line or for very small spaces.

: These are the most popular choice for modern homes because they act as both a high-efficiency water heater and a central heating boiler in one compact unit. They heat water directly from the mains when you turn on a tap, so you don't need a bulky hot water cylinder or a cold water storage tank.