In, indirect fired hot air generator discharge complete within the chamber. Hot gases, after full release, are passed through a tube heat exchanger comprising the second and third passes. A statically and dynamically balanced blower feeds fresh air from the atmosphere onto the surface of the combustion chamber. The air continues to pass through the outer surface of the heat exchanger, gaining heat and collecting at the other end of the hot air generator. The generation of hot air is within minutes of its start.