Dewayne, interesting data.  It's easier to see why horizontal loops are dug as deeply as safely and by as much as code allows - it's almost 1 degree improvement in soil temp for every foot down.

In another thread, using various 'ball park' estimating techniques, I guessed at your temperature of the soil surrounding your tubes, at 69 degrees.  I was close - I see it's 68.9 degrees!

Looks like you're making great progress learning about fluid and thermal dynamics, using data provided by the WEL.

Best regards,

Bill