What is the block in a gas boiler?

The block in a gas boiler typically refers to the heat exchanger, where the combustion gases from the burner transfer heat to the water circulating through the system. This component is crucial for efficiently heating water, which is then used for space heating or domestic hot water. The block may also include safety features and controls to ensure efficient operation and prevent overheating or gas leaks. Regular maintenance of the block is essential for optimal performance and safety.