AC,
After doing some more research, I am finding out that the thermal conductivity of the pipe vs the ground is actually not that different. My assumption was that the dirt was far less conductive, but that's not really the case. In most cases the plastic is *less* conductive than the dirt which matches what the IGSHPA general recommendations are....turbulent = good!
If you can get the heat from the water to the pipe, it will flow through the dirt as fast or faster. So any extra heat transfer you can get due to turbulence will be utilized easily. This would also explain why pretty much every residential installations have GPMs that are firmly in the turbulent range, NOT laminar. Note: One could get the same heat transfer with a much larger loop field & run in laminar mode, and this would result in a more efficient system....However, the installation cost of the larger field would most likely outweigh the small increase in efficiency over the life of the system. If you have your own backhoe and time, it *might* be worth it.
Len
|