There are two types of heat exchanger that can be within your heating unit, the primary heat exchanger and the secondary heat exchanger. The primary is present in almost all boilers and it allows the transfer of heat from the burner to the water within the system. The secondary heat exchanger is only found in a combi boiler and allows the heat to be transferred between multiple closed systems. The Primary Heat exchanger is sometimes referred to as the 'main' heat exchanger or heat engine. The se

Brand Name	Worcester Bosch