Abstract: A burner apparatus having a burner tube in which is disposed a premixing tube having air communication with the air inlet end of the burner tube. An air diffuser bridges between the premixing tube and the burner tube. A baffle plate is supported by and seals across one end of the premixing tube and a plurality of gas/air mixture injection holes are dispersed in the premixing tube between the air diffuser plate and the baffle plate. A gas tube extends into the premixing tube and a plurality of gas holes are disposed along the gas tube in proximity to the discharge end of the gas tube so that air is premixed with gas and discharged from the gas holes to form a gas/air mixture which is passed from the gas/air mixture injection holes radially between the baffle plate and an air diffuser plate.