Patents by Inventor Philip L. Drewsen

Philip L. Drewsen has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Heating system
    Patent number: 4665890
    Abstract: A heating system designed to extract more than the usual amount of heat from a given amount of fuel by controlling the route of smoke from a firebox through a smoke duct over a tortuous path and exposing the walls of the smoke duct to ambient air, thereby increasing the efficiency of the heating system.
    Type: Grant
    Filed: December 2, 1985
    Date of Patent: May 19, 1987
    Inventor: Philip L. Drewsen