Patents by Inventor Robert D. Sheffield

Robert D. Sheffield 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).

  • Tub and shower floor heat exchanger
    Patent number: 4821793
    Abstract: A heat exchanger unit to be positioned in the floor area of a bathtub or shower stall which extracts heat from spent shower or bath water, transferring that heat to water yet to be supplied to the shower or bathtub, reducing the amount of hot water required from a water heater for comfortable bathing.
    Type: Grant
    Filed: August 6, 1987
    Date of Patent: April 18, 1989
    Inventor: Robert D. Sheffield