Types of residential gas burners include atmospheric injection, yellow (luminous) flame, and power burner units. Their classification is determined by the firing method used. Gas burners can also be divided into two broad classifications based on whether they are specifically designed as integral parts of gas-fired heating equipment, as in Figure 2-4, or are used to convert a furnace or boiler from one fuel to another. The latter are called conversion burners and, at least outwardly, resemble the gun-type burners used in oilfired appliances. Gas conversion burners are commonly designed and manufactured with integral controls so that they can be installed as a unit in the existing furnace or boiler.
The burner(s) producing the heat in a gas-fired appliance is sometimes called the main gas burner. Do not confuse the main gas burner with the pilot gas burner.The function of the latter (where it is used) is to light the gas flowing to the main gas burner.
Gas burners may also be classified as inshot and upshot types, depending on the design of the burner tube. The burner tube of an inshot gas burner is commonly a straight, adjustable venturi that extends horizontally from the unit (see Figure 2-5). An upshot gas burner is characterized by a burner tube that extends horizontally from the unit and then bends to assume a vertical position (see Figure 2-6).