daestrom wrote:

For your climate, with very warm inlet water temperatures, it's a
double-edged sword. Yes, it makes these sorts of heat-exchangers less
efficient overall, and they recover less energy from the greywater.

Dr. V says the (Canadian) NRC tested the GFX during the summer and
the Power Pipe during the winter without correcting for the water
temperature difference, which made the Power Pipe look better.

And FSEC biased their tests by evaluating the GFX as an alternative vs
a helpful addition to solar water heating, and didn't test it with
water heating panels that were reoriented for more winter sun,
which would have improved the results.

And the GFX still doesn't have an US Energy Star rating. Then again,
neither do water heaters nor clothes dryers.

There seems to be a lot of jiggery-pokery here.

Nick