Granted Patent
Utility
US 4,517,807 · App. 06/640,891
Heat pump water heater with supplemental heat supply
Inventor:
James R. Harnish
Patented Case
View Patent ↗
Granted: May 21, 1985
Filed: Aug 14, 1984
Inventor
James R. Harnish
Assignee (at issue)
BorgWarner 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.