Abstract: The pressure head needed to drive combustion air into the combustion region (46) of a heat gun (930) is imparted to the air by a compressor blades (36) driven by a turbine whose blades (32) are interposed in the fuel conduit that leads to the combustion region (46). The expansion of the gaseous fuel, which is obtained from a pressurized source, provides the power to impose the necessary pressure head. The turbine-compressor combination is efficient enough that it can extract from the fuel flow enough power to maintain the necessary pressure head not only on the combustion gas (A.sub.1), which flows through vents (44) in a manifold (43), but also on a larger volume of air (A.sub.2) delivered downstream of the combustion region (46) to dilute the combustion products and thereby cool them to the desired heat-gun output temperature.

Abstract: The pressure head needed to drive combustion air into the combustion region (46) of a heat gun 930) is imparted to the air by a compressor blades (36) driven by a turbine whose blades (32) are interposed in the fuel conduit that leads to the combustion region (46). The expansion of the gaseous fuel, which is obtained from a pressurized source, provides the power to impose the necessary pressure head. The turbine-compressor combination is efficient enough that it can extract from the fuel flow enough power to maintain the necessary pressure head not only on the combustion gas (A.sub.1), which flows through vents (44) in a manifold (43), but also on a larger volume of air (A.sub.2) delivered downstream of the combustion region (46) to dilute the combustion products and thereby cool them to the desired heat-gun output temperature.