New Drilling Product Makes Geothermal Drilling Easier
A leading and long-established well drilling firm in northern New Jersey found that working with a completely new ground loop heat exchanger called “Twister,” an innovative option for use in heat pump systems, required significantly less time and effort to get the job done and resulted in savings of up to about 25 percent in cost.
The project was designed to service a 3,500 square foot residence with limited yard space in an established neighborhood in New Jersey where hard rock drilling was involved. The contractor, Colaluce Well & Pump Service, was faced with the primary logistics involved in getting to the site physically, deciding how to position the large equipment, and the operation of the drill itself. Additional considerations were how to manage the drill cuttings and water as the process was taking place.
That’s one of the reasons why the specified use of the new product was going to offer such important advantages. Unlike conventional pipe, Twister’s unique design means that its required drilling amount is about 30 percent less than would normally be needed. The job specifications called for the ground loop exchanger to be able to provide the 5-ton peak load needed. This would help produce the thermal needs for the home’s 7-ton capacity, water-to-water heat pump specified for heating and cooling.
In this case, only 600 feet of drilling was required for a system that would otherwise have needed 840 feet. Not only did that cut down significantly on the time and effort involved, but it was an important advantage in managing the volume of drill cuttings produced.
In the words of company principal, Don Colaluce, “That means that for someone with a lot of work, you can get in and out and complete the job more quickly, and then just move on to your next project. As a result, you are far more productive and able to keep your customers satisfied due to your prompt management of their needs. In this case, we were able to do the drilling in about three hours per hole—that’s really quick drilling.”
“What’s more,” he added, “by reducing the drilling depth by some 240 feet, far less groundwater would be encountered. Given the limited working space on this property, and the care required to protect it, further advantages in cost and time savings were possible. A simple silt fence installation was all that was needed to keep the cuttings from being washed out onto the adjacent road surface, so containment was easily managed.”
Colaluce also found that the twisted-pipe design of Twister was a big help when pumping in the cementitious grout mix (111 Grout 9). The product features a novel design that has four -inch pipe loops spirally wound around a central 2-inch pipe used to guide the tremie pipe. This means there is more practical use of the bore capacity to achieve maximum conductivity. Further, because the pipe takes up more of the bored hole opening, it lessens the amount of grouting needed, both in terms of material and time. With a conventional one-loop system that goes down the bore and returns through the “U” bend at the bottom, generally you need a 1-inch loop for about 300 feet and a 1-inch loop for 400 feet or more because of friction losses in the pipe. Here again, the Twister four-loop approach eliminates this complication. The project was accomplished using a DrillTek 25, 64,000-pound unit, as well as a 350 psi compressor to blow the cuttings out of the hole.
“Since there can be considerably less drilling involved,” Colaluce added, “that can allow the driller and installer to get in a more competitive bid and to potentially do less yard damage since a job can be reduced to two holes instead of three. In the specific case of this residence, the drilling took place to the left side of the home, which was completely finished and landscaped. So, as far as keeping headaches and complications out of the picture, Twister helped us to really simplify things.
“Needless to say,” Colaluce concluded, “any time you’re working with a new product, there is typically a learning curve to deal with, and sometimes, uncertainties that present surprises when you least need them. That’s not what we’ve seen with Twister, especially in the way it helped us to complete this project so efficiently. It’s delivered in easily-managed coils, so they can be moved about the jobsite without any real fuss. The shallower bores mean that there is less product to deal with in terms of footage. And, the performance is better because you are putting only one loop in the hole, compared to the conventional approaches.
“Our company has been one of the first ‘early adopters’ when it comes to using this new option, and it certainly brought advantages to the table on this project.”
According to Robert Jensen, Twister inventor and president of Agreenability Inc., “Twister offers a host of benefits that are rapidly being accepted by drillers who are looking for a truly better option that doesn’t require a long list of complicated and confusing adjustments. In fact, Twister uses standard methods for installation, so there are no issues surrounding warranties, state/association approvals or learning new installation techniques. As an incentive to promote early adopters, Agreenability is seeking qualified design/installation companies to participate in its Preferred Partnering program. Those firms joining in the program will enjoy a select status, special pricing, and gain hands-on experience to help put them ahead of the competition.”
Colaluce Well & Pump Service is a team of licensed and certified well drillers in Washington, N.J. Founded in 1929, Giuseppe Colaluce started his drilling legacy for New Jersey’s own world-renowned inventor, Thomas Edison, for whom the company drilled limestone in his N.J. quarry, which was used in his cement factory. The firm is a member of the New Jersey Ground Water Association, and their drillers have master and journeyman NJDEP drilling licenses.
For use in residential and commercial geothermal heating and cooling applications, the patented Twister (Twisted Pipe) system represents a vertical bore heat exchanger technology, which allows the simultaneous installation of four loops in a single vertical bore for greater efficiency and lower cost. The product is unique because it takes greater advantage of heat transfer and heat capacity of the soil.
Twister uses -inch pipe that conforms to ASTM D3035 (sizing) and meets or exceeds material requirements of ASTM D3350 with a Cell Classification of 445574C; meeting or exceeding IGSHPA manuals requirements. The -inch pipe is spirally wound around a central 2-inch pipe used to guide the tremie pipe all that way to the bottom of the borehole. The central pipe is also perforated to allow the grout to flow freely and encase the Twister as bottom-up grouting is performed. It is delivered on reels or in coils, and factory prepared U-bend fittings mean that the Twister heat exchangers can be slipped down the hole like a conventional U-bend loop. As a result, there is no extra fieldwork to install the Twister pipe systems.