DeHart AC & Mechanical helps Metro Tech earn LEED Gold

OKLAHOMA CITY, OKLA. — DeHart Air Conditioning and Mechanical, headquartered in Chickasha, Okla., is a fourth-generation success story. “My granddad started the company in 1920 as a sheet metal contractor,” said Mark DeHart, company GM. “After my dad got out of the war he got a mechanical engineering degree and then started in the heating and air business.”

Mark DeHart joined the company after he graduated from Oklahoma State University — the entire family went to OSU — and now works alongside both his sons. The 25-employee company serves a 150-mile radius, and offers a full range of capabilities to its customers. On the residential side they do custom homes and replacement, as well as all the service. On the commercial side they do light and heavy industrial work, with some specialty assignments. They design most of their jobs in-house, but will gladly work to spec.

And the work has been plentiful, in spite of the down economy. “We’ve had our best years the last five years in a row,” DeHart said. “Part of our success is in our employees and in the quality of work we’re known for. People start seeking out those kind of firms that can do a job right, and we must be one of them because we haven’t had any unproductive time in quite some time.”

Part of their success is also due to the company’s willingness to explore new types of work. In the same way his grandfather went back to school to add air conditioning and heating to his repertoire, Mark DeHart has tried to bring the latest innovations in his industry to his customers.

“We’ve been involved in geothermal technology for over 32 years,” DeHart said. “When OSU started their research into the application of geothermal, we were right there at the start of it.” DeHart AC and Mechanical used to see only from two to 10 geothermal system jobs a year, but over the last four years geothermal applications have seen a huge increase.

That experience made them a natural for the Metro Tech job. The Metro Technology Centers are a five-campus career and technology education district serving the greater Oklahoma City area. The latest addition to the campus is the Metro Career Academy, a 54,000-sq.ft. facility that offers vocational training for at-risk high school students.

The new facility was designed to incorporate the latest in eco-friendly and energy-saving technology, including a green roof, a cistern-driven rainwater reclamation system, sustainable landscape design, and an integrated 223-ton geothermal heat pump system.

Combined, the efficient building design and sustainable building methods helped the Academy become the first LEED Gold-certified building in the state. DeHart AC & Mechanical served not just as lead mechanical contractor, but also as LEED commissioning liaison for all the project’s mechanicals.

Mark DeHart said that most of the geothermal work he’s seen has been on the institutional side, since most of the time it’s municipal organizations able to put up a bond that can afford the initial outlay.

“With the combined long-term energy savings and lower service costs over the lifetime of the equipment — as well as the tax rebates that are available now — it’s created a top-of-the-line deal for a lot of these people,” he said.

For the geothermal system, DeHart AC & Mechanical contracted B&H Mechanical out of Washington, Okla., to drill 121, 300-ft. deep wells, including a 610-ft. vertical loop and approximately 80,000-ft. of 1-, 1¼-, 1½-, 2-, 3-, 4- and 6-in. high-density polyethylene (HDPE) pipe buried at 48-in. depth. Overall, the well field was designed to accommodate the 175-ton capacity of the building’s HVAC system, as well as 17-tons of hot water heating.

“We had some scheduling to do to get our geothermal wells drilled,” DeHart said. “They were under the parking areas, and getting the drilling coordinated with the lightpole drilling afterwards was a chore. We had to get that done first since the slab was lower than the parking lot. It created some accessibility issues.”

To house the majority of the connecting pipes, DeHart and B&H created “The Vault,” a custom-built 15- x 10- x 15-ft. area constructed from approximately 15 yards of concrete and 1,500-ft. of steel rebar. “It has a manhole, so you can go in and isolate any of the loops for service if there’s a problem… there were 133 loops, and more than 8,000-ft. of horizontal line looping everything to the header plates,” DeHart explains.

The interior HVAC system is tied to the vault via two 6-in. polybutylene supply and return pipes which feed into the heating and air conditioning units via a VFD pump. The pump automatically recognizes the required number of supply gallons required for the current operating tonnage and can adjust supply as units come on line or go off line — a real boost to system efficiency.

DeHart AC & Mechanical then installed 49 ClimateMaster units, including Tranquility Rooftop (TRE) package units, Tranquility 20 Horizontal (TSH) units, and Tranquility Modular Water-to-Water (TMW) units, all of which use the environmentally friendly EarthPure HFC-410A refrigerant. The water-to-water units supply all domestic hot water to the kitchens and bathrooms.

A factory-installed DDC control system from ClimateMaster allows building operations and management staff to monitor the functionality of each and every unit, including remotely from any laptop or hand-held device with an Internet connection. DeHart AC & Mechanical’s work began at the start of 2010, and finished in July of 2011. The overall total mechanical was a little over $2 million. “We had a few change orders along the way, but not many,” DeHart said. A few balancing issues needed to be resolved, as is common with any large building. The Academy is now LEED Gold certified, and projected to be the most energy-efficient building on the Metro Tech campus.

The job has become a showpiece for the company, and an opportunity to show how their best work can deliver value to their customers. “We’ve been recognized for the quality of work and the craftsmanship we put into the job,” Mark DeHart said. “A lot of people have called to ask us to come bid their job, which is always better than having to scrounge for it. We’ve been very rewarded and pleased we took the job on.”