jamesgang wrote:

I believe he said "reduce summer time costs". And it does do that
since ground water and city water are usually a lot cooler than
summer air temps.

You are correct. He wrote,

"Having a second tank that's unpowered, uninsulated, and plumbed in series
so
that cold water passes through it first will reduce summertime AC and water
heating costs by naturally warming the inlet water up to room temp."

I didn't catch that part - that he meant in the summertime with the AC on
etc.