Granted Patent
Utility
US 6,672,371 · App. 09/237,754
Earth heat exchange system
Inventors:
Thomas R. Amerman, Howard E. Johnson, Jr.
Patented Case
View Patent ↗
Granted: Jan 6, 2004
Filed: Jan 26, 1999
Inventors
Thomas R. Amerman
Howard E. Johnson, Jr.
Assignee (at issue)
Enlink Geoenergy Services, Inc.
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.