Thanks- I'll be having raised beds with irrigation and thought the irrigation water could/t hurt efficiency.
My rule is at least 12" below what the local JHA wants for a footer. The loops if as deep as I think is good should not give tender shoots cold roots. In spring the dirst warms from both directions. This is all just solar heating. Very long term, but still solar. Tjames: Just got home from a spending frenzy and am not yet hitting on all 8 yet. I would direct you to the December issue of Plumbing and Mechanical that crossed my desk today. It contains an essay by Siggy on what we have been typing about. Mark