I'd like to check in here to affirm that I understand what this is saying (noting the correction too that this is for a 4 ton system):

I have clay soil, I'm in a cooling dominated climate (not building though), have an 8 ton bore hole field (2400' bore length total), and my holes are spaced about 20' apart.  Does this indeed say:
 
* I'll probably experience some amount of ground Delta T heating over the years?

* In my case, noting the bore length I have and the 20' spacing I have, my ground Delta T heating over the years will be negligible?

Many thanks!

Best regards,

Bill

Bill,

I doubt that your clay soil is dry. So assuming that your soil is at least damp, I think you can rest assured that your Ground Delta will be negligible.

Dewayne, thanks.  I agree - I'm probably higher up on your soil characteristics chart.

It's interesting to see that all clay compositions are in some kind of 'rare' category.  I didn't realize my Texas clay soil wasn't as common as I thought.

To stay out of a 'rare' or 'extremely rare' category, my guess is I have Damp Silt/Clay or Saturated Silt/Clay.  And based on the amount of water that came out when my holes were drilled I'll guess I have Saturated Silt/Clay.

This is an interesting subject.

Many non-geo HVAC contractors in my area include this 'fact' (heats up the soil, grass won't grow so well, etc.) to pursuade potential customers to install conventional or air-to-air heat pump equipment.

I think I'll contemplate how I could use my WEL instrumentation system data to eventually prove with fact that indeed there's no ground heating effect.  While I don't have a ground temp probe, my guess is EWT shown in some manner would suffice (i.e., rolling 12 month average EWT over a 10 year period - 108 data points).

Thanks!

Best regards,

Bill

If heat keeps grass from growing, how come you still have to edge an asphalt driveway? Don't they get a little warm in the sun?