Vaillant has two kinds of heat exchangers that can be within the heating unit, the primary heat exchanger and the secondary heat exchanger. The primary is present in almost all boilers and it allows the heat to be transferred from the burner to the water within the system. The secondary heat exchanger is only required in a combi boiler and allows the heat to be transferred between one closed system and another.

• 13 plates
• Screws and O-rings included