A gas boiler uses natural gas as its fuel source to heat water, similar to other boiler styles. Gas boilers can provide significant savings compared to other fuels like oil or coal. High efficiency condensing gas boilers employ additional heat exchangers to make use of extra heat from exhaust gases. Gas boilers can provide immediate hot water and controllable heating without needing to store or order fuel. They typically cost less than one thousand pounds and are compact with high energy efficiency. Common types of gas boilers include regular boilers for homes with low water pressure, combi boilers for space-saving designs, and system boilers that integrate efficiently and provide hot water on demand without a storage cylinder.