Vaillant Connection Tube Complete is located within the heat exchanger section. There are two different types of heat exchangers that can be present; they are the primary heat exchanger and the secondary heat exchanger. The primary is present in almost all boilers and uses heat from the burner to raise the temperature of water within the system. The secondary heat exchanger only appears on combination boilers and allows the heat to be transferred between two closed systems.

Brand Name	Vaillant