Granted Patent
Utility
US 6,167,715 · App. 09/167,429
Direct refrigerant geothermal heat exchange or multiple source subcool/postheat/precool system therefor
Inventor:
Thomas H. Hebert
Patented Case
View Patent ↗
Granted: Jan 2, 2001
Filed: Oct 6, 1998
Inventor
Thomas H. Hebert
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.