Kelix is a very unique sytem that should provide more consistent results than PEX tubes. www.kelix.com

References?

Data?

Lots of sizzle at that website, but I need steak

I sent them an email...it came back with this:

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The Kelix system is rather new but after reading a number of test reports and applying sound engineering principles I was sold that their system made much more sense than two pex tube pushed down a hole. Additionally, in reviewing numerous typical PEX geo systems I found some got good results and some got horrible results. If you watch two pex tubes with u bend pushed down a hole I wonder how much mud is being pushed off the walls of the well. I wonder if the the two pex tubes are twisting around each other. Are they wedged in the hole and the remaining tubes just being slinkying on top of them. When the grout finally sets up in the hole, how do I know I have a consistent and solid bed between tube and well wall. Tons of variables. With a Kelix system you have a 3.5" thin wall rigid fiberglas pipe pushed into the hole with an end cap on it. It goes down about 300'. You then use a grout, preferably Supergrout, in the annulus area between pipe and well wall. This annulus distance is 1.75". Inside the 3.5" pipe goes another pipe that has twisted flutes on the outside of it. Imagine a twizzler. During cooling or heating, water from the heat pump goes down the center pipe and then returns up the area between inner and outer pipes. The flutes on the exterior of the inner pipe cause the water to spin outward against the outer pipe. This would be similar to a scraped surface heat exchanger. Flowrates run up to 18 gpm. This yields velocties that run in the turbulent range. Consequently, heat transfer is significantly improved under turbulent conditions. As you can see, much less opportunity for variability. I am installing a couple of these systems. I am a mechanical engineer, PE and did Masters Work on Boundary Flow.

Please let us know how they perform. I am skeptical of a system that claims to get so much heat from so little bore hole. The TC of the ground would be a big limiting factor.

The inventor claims that one can get 5 tons of heat or cooling from one 6" dia. hole x 300' deep. I too, am a bit skeptical because my soil in Savannah, GA may not be as good as his in Oklahoma at transferring heat. With 2 ea. 1" dia. pex tubes you can only transfer so much heat through the perimeter of the tubes. That would be ~ 6" for the two tubes. But, are you transfering heat from one tube to the next. But, with a 3.5" tube, you have 11" of surface. Right there you have nearly 2x the opportunity for heat transfer. Additionally, now run at turbulent flow levels and the h factor for convective heat transfer goes way up.

Having said all that, the test verified test data where the hole was hammered for 48 hours continuously showed a 3 ton relief of heat to the earth, but both inlet and outlet temperatures continually increased. This is not a realistic real world test. I have a 6 ton load and was going to need 2 wells whether I believed 5 tons or 3 tons per hole. I will monitor flow rates, and delta T's.

I have learned that one must be much more careful about the installation and grouting than one does with PEX. But, if I can only drill one hole for Kelix instead of 5 Pex holes I will be a very happy guy.

Savannah is close enough for me to make a road trip to check it out.

Boreholes are a huge expense relative to the rest of the system, and on some beachfront lots we are very space constrained, so anything that reduces the number of bores is attractive

Waiting on a grout for another hole I need to drill before tieing all systems together. I will let you know when it is ready.

I'd like to see it when it is done.

And then I'd like to see how it is doing in mid to late August this year after the cooling season has been going for 4 months.

The thing about cooling is that there is no such animal as an "auxiliary cooling strip" to bail you out during extreme weather.

Then I'll want to know the incremental cost in drilling a 6" borehole for Kelix vs 3" needed for conventional U-tubes.

3-4" wells are common residential sizes. 6" is commercial / industrial, so there's a big difference.

Bound to be interesting.

What type engineer are you and for how long?

BSEE, degreed in 1988, registered in 1992.

Nearing 22 years in the care and feeding of industrial process control systems with an emphasis on continuous processes. Have been involved with Steam systems to 600 MW and chilled water systems to 10k tons.

I'm unsure of the relevance of your questions on this site - do tell.

Well, BS/MS ME here. Degreed in 77, PE in 81. Registered in SC/GA. Background is continuous process operations in chemicals and food processing. Operated and installed steam, cogen, and chw systems. One site operating had 15000 tons of chilled water. Installed 2 coal fired boiler systems.

I am sure you are quite competent as a EE and I am quite competent as ME. Honestly, my weakness is process control because I have always had great control engineers that took care of that. But, I was the one that was on the line for the size of the boiler, chiller, cooling tower, heat exchanger, cooker, piping, plus all the structural work that goes with those things.

Consequently, I consider this geothermal stuff to be just basic mechanical engineering involving fluids, thermodynamics, and heat transfer.

I have contacted them via phone and will wait and see what shakes out. My concerns are claims that you can get "up to five tons per hole" to me the skeptic this sounds like a math extension of a limited test result if everything is perfect. Second concern is cost, and time to install. All of these things need to come into play to make it market attractive.

While not trying to be offensive, your statement above about basic mechanical engineering involving fluids and heat transfer is very true at face value. I find myself defending the position that it takes "boots on the ground in conjunction with engineering" to have a happy outcome to a project. It has been my experience that when you try to get to cute with a "borehole" trouble is coming. Spacers on the lop to hold them apart, and two loops in one borehole, come to mind.

Eric,
I fully understand your viewpoint too. I am not affiliated with Kelix in anyway other than mailing them checks for equipment. My experience with Kelix is that I have two holes in the ground and two more to drill. Well driller screwed up one hole very badly and is no longer on the job. 40 years of well drilling did not make him an expert. The guy just would not listen and decided he would do it his way. A Kelix system is not for ole Bubba to just slap in a hole. It takes paying attention to detail and following directions. There are many geo holes with PEX and software written that models those installations. The PEX installations are pretty simple when compared to Kelix. Once the hole is drilled, it takes about 90 minutes to install the outer pipe. Grouting if done with Supergrout is a bag of Supergrout and 5 gallons of water. - very simple. Grout is consistency of, and looks like, choc. milk. Pumps easily with 3/4 trim tube. You have to remove the trim tube as you grout or the positive displacement pump for the grout can build too much pressure and rupture the thin wall outer pipe. The outer pipe is in 20' sections that are screwed and epoxied together. My experience is that all materials and labor ran about $9K per hole. I think you can figure your trade off if the hole delivers 3 tons, 4 tons, or 5 tons vs. the typical PEX hole.

I would be interested in seeing your comparison.

Someone may but I don't know anyone using pex in vertical installations. Perhaps you mean HDPE.
The ground is always the limiting factor to a loop's capacity. We get about 1 ton out of a 150'/ 3/4" vertical u tube in MI due to presence and flow of ground water (this design comes from a local geo loop designer trained by Doctor Bose at IGSHPA). You would get about 40% more with a double u tube (3/4" by the way) according to the Engineers at Climatemaster (based on their sizing chart). The only way to know loop field capacity for sure in vertical applications is to have a testing outfit core bore the soil and design it for you.
You can have all the degrees you want, but without knowing exactly what you are drilling into, you are shooting in the dark. That and the use of an unknown product.......
Doesn't sound very scientific.  
However, I am always glad to acquire data at someone else's expense and I truly wish you well. Please keep us posted.
Joe

I agree you can have all the degrees you want and a degree does not make one smart. I come from a very blue collar family where I grew up working for a mechanic/electrician. I run a huge maintenance department as part of my organization. I clearly know the benefits of both education and hands-on experience. That last driller I had that would not pull his grout tube out of the hole until he had 100' of grout in the hole despite my insistence paid me back about $9000 for his screwup.

Thank you for the opportunity to quote you a cost commparison. I sell 5 tons at a rate of 1,500.00 per ton that includes 200' of active pipe per ton, all manifolding, flushing and charging with 20% methanol, installation of the pump pack, and the connection of the loop field to the unit, and the subsequent flushing and purging of the unit. Bore holes are grouted from the bottom to the top with groutwell df at a ratio of 50# of grout to 20 gallons of make up water. Time to construct and loop and grout one 200' bore hole on average 35 minutes. To me that is quite a savings in time and certainly money.

Whoa, are you telling me that you can set a rig, load pipe, bore 200', pull all pipe, land all pipe in carosell or rack, mix grout, make up u bend, fill hole with grout and put hdpe pipe in hole and do this in 35 minutes. This is hard to believe.

I can get a 4" diameter geothermal well drilled around here for $5/ft. Assuming I go down 180' with one 3/4" U tube per ton of capacity, that's $900 for one hole drilled. Assuming $.50/ft for 3/4" HDPE 160 psi pipe, that's ~$200 for the U-tube heat exchanger down that hole. Assuming $500 for the grout material cost and the cost to pump it and install the pipe for one 180' hole. That's a total of $1650 for one bore hole heat exchanger for one ton of capacity. For 3 tons of capacity, I'm looking at around $5000 for the vertical heat exchanger for my 3 ton geo system.

You are correct sir.  35 minutes is average for above.
Most of what we do is proprietary information, however what I am willing to show and share is in the galllery at our website.  I will say that the equiptment we have has been heavily modified for the sole purpose of installing geo loops.  We have been at it since 1988.  Practice makes perfect and perfect makes production that drives the cost of install down based on production rate.
  We do commercial as well as residential and llife is good. 
Eric