Granted Patent
Utility
US 6,820,421 · App. 10/252,744
Low temperature geothermal system
Inventor:
Alexander I. Kalina
Patented Case
View Patent ↗
Granted: Nov 23, 2004
Filed: Sep 23, 2002
Inventor
Alexander I. Kalina
Assignee (at issue)
KALEX, LLC
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.