http://blog.heatspring.com/geothermal-performance-case-study-closed-loop-vs-dx-vs-kelix-thermocouple/?utm_source=HeatSpring+List&utm_campaign=0260a33247-June_2012_Newsletter&utm_medium=email

Heatspring story about a new vertical ground heat exchanger. Seeking comments and thoughts.

It may be a viable alternative to HDPE where as the article states cost per foot is in the 18.00 range. IMHO that 18.00 per foot to drill number is rarely occuring. If they can squeeze more tonnage out of a shorter loop it may also have an application in space constricted areas where you just can not fit enough hdpe holes and the cost to go monster deep is to high. Just a few random thoughts.
Eric

The main item that struck me after I published the post is the few nasty emails I received.

Oh no, they are using double u-tubes, high performance grout and terms like "cross talk". "Geo pros" tell me these things are "voodoo".

More seriously, better heat exchange can certainly shorten loops but what is the long term effect of drawing from a smaller volume of soil, especially where ground water flow isn't involved?

The author is surprised by the push back from the community.

When they make claims like

"20-50% BETTER HEAT TRANSFER"

some body needs to call them on it.

Here was my comment:

"Having about 15 or our systems on the Web Energy Logger, I looked with interest at the data presented here.
I cherish any kind of objective study conducted, but I also stress caution since a lot of facts are unknown, especially the methods used.
At first some initial questions come to mind.

If this is used for comparison between Kelix and conventional U-Tubes, why were differently performing grout used? This fact itself makes a direct comparison between those different loop systems impossible.

The deep ground temperature in the MA location appears to be 59F. While the actual building is unknown, the graph "Kelix/Thermocouple cooling analysis" indicates that putting a cooling load onto the loop (heat rejection) on march 13, 2010 for a period of 5 hours raises the loop temperature (EWT) from mid 50s to low 90s. To have that high of a raise in the mid march at mid 50 ground temp indicates a short loop or underperforming loop situation, as also indicated by the quickly dropping EER.

The graph "Cooling – heat rejection analysis, three different outside heat exchanger fields" indicates an about 15 degrees F higher loop temperature and a raise in temperature of the Kelix loop compared to the u-bend during the month of July 2011, again, suggesting an lesser performing loop for the A/C load. This is in contrast to the u-bend loop which is running 10-12 F cooler and actually decreasing in temperature, indicating and overperforming or oversized loop. The gross difference in the total amount of BTUs rejected into the loop suggest a very different load, not a different performing loop.

In summary, the data presented here suggests a short/underperforming Kelix loop, and an oversized/overperforming u-bend loop for the load they carry, but also very different loads rejected into the loops."

It is allways the same story, skewed data. Or making the data say what you want how you want. The push back by proffesionals is due to long time usage and dependable results with the exchangers they currently use. Claims that you can decrease and gain 50% are allways goint to be met with skeptisism.

Long term data by those chooseing to embrace new advances will allways ring true. The pro's are allways going to be leary as we allways trade on reputation and satisfied customers first, not claims by factory or product reps.

Eric

If only the earth would cooperate by moving btu's faster, lots of things would move btus better than our current loop designs.

I am interested in the "Bit of learning curve" needed for installing these systems.
Seems like its another idea that may work in some cases, but not going to change the industry at all.