I'm sure I have in my collection of old books one from the earliest decades of the 20th century explaining how to thaw fire hydrants using I^2R. There is also a detailed description of how to dry out flooded xfmr and motor windings by the same method.
Of course, you do hazard the unpredictable effects of stray currents this way. Some of these same publications recommend using one's tongue to test the polarity of DC circuits, or dangling a candle at the end of a length of solid #12 to explore hollow walls...
We have learned a great deal about safety since then.
Now, the closed-loop hot water deal, that's clever. It makes me so glad I live in central Texas where I don't have to be that clever!
