GTS Comtherm PMB series Premix Gas Tunnel Burners consist of a specially designed burner nozzle orifice and refractory burner block, which provides reliable flame retention at various mixture pressures with higher heat release. These burners are more efficient than atmospheric burners as greater control is available over the air and gas mix, a hotter flame is produced. Our Premix tunnel burners have a shorter flame length and the air/gas ratio is easier to control and the burner overall is generally easier to set up.