Eric, Have you ever tested or considered supergrout? With your grout mixture do you ever have it tested for thermal conductivity values?

Sounds like you are doing things very right. If one has a good bit of real estate, then the typical system you install is a great deal in my opinion, but if you have one of those 50x90 lots in the city of Chicago, then a Kelix system is one's only hope.

When you do a 5 hole bore, what is the typical size pump in gpm and horsepower are you installing. A big item overlooked is pumping power required in systems. I have seen people put their wells 2-300 feet from their house and I think how much of their savings they are giving away.

The groutwell df is a standard one sack bentonite grout. It has a conductivity of .40 I think, going on memory. In saturated soils I do not think thermaly enhanced grouts have any merit. Also reducing the number of bores based on a grouts performance on a commercial project is engineering gone bad in my opinion.
That being said I believe that it is a very usefull tool in a rock bore or unsaturated soils.
We never loop more than 100' from te machine on residential for exactly the reasons you mentioned. For a five loop 200' 3/4" project within 100" of machine, close headered on 1 1/4 hdpe for the run, I prefer the flowcenter unit bgm 136. Installed with a trottling valve on the outgoing side for fine tuning.
Eric

I too have a interest in the SuperGrout product if anyone has ever used this it, I would like to know.

I have  used Super Grout.  It  is nice to work with and pump.  I just can't justify the cost.

Hey Dewayne,
how much did you have to pay per bag? I went to their site and did not get the specific info I wanted. I did run their calculator and found it required a ass load of bags per hole. Are they 12# bags like te graphite?
Regardless of the engineering data I am skeptical to believe the claims of increased thermal performance based solely on grout. Grouting is still one of the stumbling blocks for geo drillers. If designs are based on thermal grout performance and something during grouting is not exicuted properly you have the equvilant of short looping?

Does anyone know if a study has been done running 4" or 6" HDPE pipe in a horizontal ground loop? It looks like if this Kelix system can use a 6" pipe vertically and have enough pipe to ground contact to not lower the ground temperature to much in the winter it should work horizontally also.

Right off the bat I'd expect an issue from inability to maintain turbulent flow. In addition, thinner pipe gets more loop fluid nearer more dirt

Here are some answers.

- Supergrout has a thermal conductivity of around 1.

- Each bag of Supergrout mixes with 5 gallons of water and has the viscosity and color of chocolate milk. Pumps very easily.

- Particle size of supergrout is very small. Consequently, it setups very tightly giving a better K factor.

- Please let electrical engineers do electrical engineering and mechanical engineers do mechanical engineering. Yes, turbulent flow is maintained and heat transfer is improved on a Kelix system by applying boundary layer principles in the flow.

- Before saying you use too much Supergrout, remember that one 6" Kelix hole is supposed to do 5 tons and a typical 4" HDPE hole will do 1 ton. Therefore, it will take 5 typ. holes to equal one Kelix hole. Calculating cross sectional areas and adjusting for one 300' hole, and 5 ea. , 200' holes, then the typical geo holes will require 2x as much volume to fill with grout.

Eric,

Supergrout comes in 70# bags and costs about $25 per bag plus shipping. My grout costs would go from $.12 per # to $2.25 per # if I switched to Supergrout.

I recommend getting software such as "Ground Loop Design" (trial is free) and trying different grouts, borehole configurations, pipe, etc. The results will surprise some people.

Much of this software is for non engineering folks that do not know how to properly calculate heat transfer via conductive and convective means. I do not believe any of the programs use finite element modeling to develop a suitable heat transfer coefficient but have converted the basic heat transfer calculations to software.

I paid somewhere around $22 per bag for Supergrout.

Dewayne, what are thermal conductivities for the grout you use? Someone above said that using thermally enhanced grout may not be a good idea. I strongly disagree. Limiting the thermal transfer to earth is a long term killer of geothemal. You must do all you can to move the heat from the tube to the earth. You also want a grout that setups to form the most homongenous and non void type material you can. I very much like how Supergrout takes a few days to settle, hydrate, and form a homogenous solid. Before using I even made test columns and buckets and then cut them in various directions. I was very happy to find a very homogenous material. I even sent samples to Supergrout for analyzation to assure particle size and minimal spacing of particles.

I know we all have different ideas about what is right and best. As an engineer, I appreciate the trade off between cost of materials and ultimate delivery of energy. I hate the "I think", or "My intuition", etc. without backup and I try and be as factual as possible.

I am at .17 per pound in the door for groutwell df, and .18 per pound for thermex. I could never market any product at 2.25 per pound to finish a hole.
We all have software, some shareware, some very expensive purchased. We have all "played" with the numbers and seen the different results from the estimators. What is missing in this is the field application. Many thermal grouts call for high silica sand. Is all sand high silica? Is all make up water ph balanced. Do any of te engineering firms verify grout quality? These are the aplication flaws of super grouts in a field application. These flaws are not the fault of field personal, it is about the money.
A residential customer will never bear te cost of a enhanced grout. Commercial projects get awarded to the lowest bidder, with no follow up as to standards in the specs or slump/thermal tests in the field.
Geo is still so new that the field engineers most of the time do not know any more than the new low bidder for a project.

> Supergrout .. 70# bags and costs about $25

So $.36/lb. Sounds like you need to find a closer source.

Dewayne, just for the info, but Geo Supergrout is trying to get Intermountain Drilling Supply to stock it. That would most likely remove any extra shipping. And, the cost per bag would most likely range from $22-$25.

The biggest benefits I see with the idea of geo supergrout is that it expands when it cures. In dry soils, bentonite grouts can shrink--which blows the thermal conductivity out of the water. It disconnects the loop from the earth, and then you're stuck with loops that don't perform...

I'm not a fan of geo supergrout's price, at all, but I can't say the product isn't impressive.

We mix grout and sand to get TC's between  .9 and 1.2 depending on what the design calls for.

Coastall

Are your loops completed yet? Kelix sounds interesting.I would love to hear how it works out for you. What will your loopfeild cost when its complete and how does that compare to the cost of a conventional loopfeild in your area? I have to admit I am a bit skeptical,and not about the systems ability to transfer heat better than a conventional HDPE loop, but that it wont over-cool or over-heat the ground around it. Have you talked with anyone else who has used this system? (besides its inventor)

Any progress?

ANY one else used Kelix?