The same situation would apply with a header tank.

Has anybdoy circle over the airport until both tanks were near empty?
Has anybody measured the temperature of the return fuel?

I haven't measured the temp. in my sump tank, but after landing
recently I touched it and it was ambient temperature.  60 degrees F.
My sump tank is only 1 gallon with two internal fuel pumps that I run
all the time.  I only turn one off when at altitude on cross-country,
otherwise I leave them both on.  I think the fuel heating up is a
non-concern, at least as far as I can tell.  The fuel return is to
the sump tank in my plane.
--
Perry Mick
Duckt N7XR
http://www.ductedfan.com

Interesting Perry. Thanks.

Paul Lamar
 
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