Granted Patent
Utility
US 4,621,686 · App. 06/655,448
Water vapor-condensing secondary heat exchanger
Inventor:
Hongsik Ahn
Patented Case
View Patent ↗
Granted: Nov 11, 1986
Filed: Sep 28, 1984
Inventor
Hongsik Ahn
Assignee (at issue)
Intertherm 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.