Burners: The GAS burners are especially studied for wall hang boilers and instant water heaters with gas of the first, second and third family. This burners offer the possibility to have a modulation until 20% of the nominal power. They are part of the partially premix burners, and their combustion is realized with primary and secondary air.The burner is composed by the burner body, plate, spacer and collector. In order to satisfy the various application needs, it is possible to choose the burners bodies with different forms and geometric styles and the heads with a variety of designs in the sheared part.The solutions are particularly adapted to: Applications for instant water heater exchangers Applications for wall hang boiler exchangers Applications with the request of a major primary air quantity Applications with city gas (small quantity of primary air) Another important characteristic is the noiselessness.