Heat exchangers are devices designed to transfer thermal energy between two or more fluids or gases without mixing them together. They facilitate efficient heat transfer for heating, cooling, or temperature regulation in various industrial, residential, and commercial applications.

Boilers typically include a main heat exchanger, where energy is transformed from burning gas or oil to a primary water circuit.

Combination boilers usually include a secondary water to water heat exchanger where heat energy is transferred from the primary water circuit to the secondary domestic hot water circuit.