The Charles Machine Works Inc. (CMW), based in Perry, Okla., is known worldwide for its Ditch Witch® construction equipment. True to its longstanding reputation for innovating cutting-edge utility/construction solutions, CMW has recently developed horizontal directional drilling (HDD) equipment that is being used in the growing geothermal industry.

The company is not only innovative in its product development, but has exhibited an ongoing commitment to incorporating the latest construction technologies and methods into the design of its expanding Perry headquarters. This has included three geothermal projects over the past 21 years — a 45-ton system for its 14,000-square-foot training center, a 160-ton system for its 30,000-square-foot electronics building, and, most recently, a 150-ton system for its 28,800-square-foot product development center.

Seeking Efficiency

“As a company, we’ve made a living out of serving the underground construction industry, and to stay on top of the latest trends and understand the newest innovations, we figure there isn’t a better way than to install them at our own facilities,” said Tony Guinn, plant engineer for CMW.

According to Guinn, he and others at the company initially familiarized themselves with geothermal system concepts via relationships with nearby Oklahoma State University, where the International Ground Source Heat Pump Association (IGSHPA) is headquartered.

“IGSHPA is leading the charge in creating a global awareness of geothermal’s benefits, and the organization was a great resource for us in learning how and why to incorporate these systems into our building projects and upgrades on the campus,” Guinn said.

Working with Stolhand Heating & Air Conditioning, Ponca City, Okla., and manufacturer’s representative Air Products Supply, Oklahoma City, CMW designed its latest geothermal project, a retrofit system for its existing product development center, with new simultaneous heating and cooling heat pump units from ClimaCool Corp. The three 50-ton ClimaCool SHC onDEMAND® modular chiller units were specified to replace an antiquated reciprocating chiller-driven HVAC system installed during the building’s 1978 construction. The existing chilled water system had a capacity of 1,853 thousands of Btu per hour (MBH) for cooling and a natural gas-fired boiler with a capacity of 1,853 MBH for heating.

“As part of an overall assessment of how we could make our product development center more energy efficient, and ultimately shave a considerable amount of operating costs, we knew some significant HVAC upgrades would be in order,” said Guinn. “We were doing a lot of work to improve the building envelope performance, including replacing the floor-to-ceiling window walls, which make up the entire south-facing side of the building, with low-E glass.”

Blending Energy

Darrell Stolhand, owner, Stolhand Heating & Air Conditioning, was keen on specifying the new SHC onDEMAND units from ClimaCool.

“I’d been to training with Air Products Supply and was highly impressed with the unit’s ability to generate heating and cooling simultaneously,” Stolhand said. “The goal was to save money, and a system like this that can blend energy versus just blast heat or cold seemed like the way to get that job done. Also, the comfort level of this type of system is exceptional, especially when considering the design of the building, which includes two levels of an open floor plan and a south-facing wall made entirely of windows.”

According to Stolhand, the SHC onDEMAND units’ ability to allow any module to be indexed for heating or cooling regardless of its position in the bank — providing optimum module/compressor runtime equalization — was also viewed as a significant benefit.

Each of the three, six-pipe ClimaCool SHC onDEMAND units also feature a modular design with built-in redundancy with separate module electrical feeds and dual independent refrigeration circuits, allowing for the unit to maintain operation while individual modules are being serviced.

Stolhand explained that this provides a significant advantage for CMW, “as it means there’s no downtime in the facility when maintenance or other system adjustments are necessary.”

Darrin Beller, president of Air Products Supply, said the heat pump unit reduces energy consumption. “Features such as the CoolLogic Control System and integral motorized valves for variable pumping can result in cooling efficiencies up to 25 EER and heating efficiencies up to 5 COP,” he said.


The SHC onDEMAND unit was specified as part of a new 150-ton system at CMW’s product development center that also incorporated two existing air handlers with replacement Wilo brushless dc motorized pumps for load demand sensing. The controls system and fresh air vents with an economizer, considered state-of-the art when originally installed in 1978, were also replaced with a Web-based building automation system (BAS).

“The new BAS provides much more control than the previous system, and really brought mechanical operations to a whole new level in the building,” said Mark Furgason, sales and service manager at Automated Building Systems, which designed and installed the BAS.

According to Furgason, the system includes a graphical floor plan of the building that shows all zones and readings from their associated temperature sensors. It allows Guinn and others at CMW to monitor temperature in real time, as well as easily make any necessary adjustments.

“The system allows you to adjust operations either onsite or remotely from any Web-based device, including a computer or smartphone, and can also send alerts about system operation changes or problems directly via email or text,” Furgason explained. 

Geothermal Construction

Initial geothermal field drilling for the project began in September 2011, simultaneous to digging for new French drains on the north side of the product development center building. “This was our first vertical-loop geothermal project on the campus,” said Guinn.

In all, the field includes 168 400-foot-deep boreholes with high-density polyethylene (HDPE) double U-bend pipe installed throughout.

The drilling was conducted in tandem with the construction of a separate foam-insulated 20-by-24-foot mechanical building that houses the new ClimaCool units and ancillary HVAC system equipment.

“With our original HVAC system, the chiller was external to the building, and the boiler, which we removed, had been installed in the shop,” Guinn said. “We really needed a separate space for the new equipment, and also had a goal of making it a showplace of sorts, to use as a model for how this innovative system looks and operates.”

According to Guinn, the building’s dual steel-wall construction was designed to be highly energy efficient, as well as provide a clean, finished look for those visiting the space.

In addition, an underground vault made of waterproof polyethylene was constructed to house the geothermal ground-loop manifolding system.

Upon the March 2012 completion of the loop field, the ClimaCool unit was installed and initial flow testing was conducted.

“After the commissioning phase, the ClimaCool system has performed very well,” Guinn said. “We locked the thermostats at 73˚F to eliminate user fluctuations during last summer’s heat wave, and the system kept the building very cool and comfortable at that temperature.”

Guinn additionally shared, “We’ve been operating on only half of the complete borehole field to date, as Ditch Witch is using part of the field for performance testing. When the testing is complete, we plan to use the full capacity of the field.”

Guinn continued, “We are still waiting to see what happens when the system’s been operating longer-term, but we expect that we’ll be seeing about a $50,000 savings in annual operating costs.”

Information courtesy of Automated Energy Inc., an Oklahoma City-based consulting firm dedicated to empowering energy customers with the information they need to make smart energy decisions. For more information, visit

Publication date: 11/18/2013 

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