Case Studies in Commercial Ductless Applications: Mitsubishi VRF Meets Diverse Comfort Requirements

A five-building facility with so many spaces, with each space dedicated to occupant experience, required an HVAC system with advanced controls.

In the early 2000s, the Oklahoma River was dammed up as part of the MAPS1 community improvement initiative. The project not only accomplished its goal, but set the stage for a vibrant riverside filled with attractions and stunning architecture. The Oklahoma City (OKC) Boathouse District is central to that vibrancy, with six buildings offering athletic training facilities, event spaces, activities for children and adults, and more. For such a wide range of cooling and heating needs across its six buildings, the five newest Boathouse District buildings now use Variable Refrigerant Flow (VRF) from Mitsubishi Electric Cooling & Heating.

John Riggs, senior director of operations, OKC Boathouse Foundation, assists with all construction projects on campus and oversees the maintenance of the facilities and grounds. He described the Devon Boathouse — the first building completed with Mitsubishi Electric VRF — as a “stunning, high-performance facility, and a designated U.S. Olympic & Paralympic Training Site. There’s a little bit of everything across its 33,000 square feet: a dynamic rowing tank; a gym with a free-weight area, kayak ergometers and treadmills; locker rooms; an event room that holds 200 people seated; an endless pool; a high-altitude chamber; and multiple boat bays.”

A facility with so many spaces, and with each space dedicated to occupant experience, required an HVAC system with advanced controls.

“This is about access – the ability to remote in and change things on the fly. A high level of access and control means you can manage energy costs and customers’ comfort. VRF offers that kind of access,” said Riggs.

VRF was also extremely flexible and discreet in its design. The Devon Boathouse features glass and polycarbonate walls to create an open feel.

To match that aesthetic, the HVAC system’s indoor and outdoor units both needed to be unobtrusive. Riggs said, “We couldn’t have anything on the roof – that’s just how it is on the whole campus. Nothing on the roofs. Everything’s gotta be straight lines. And all of the buildings on campus are triangles, so they have this crisp, clean look. We needed a system that could match that.”

Damon McClure serves as the project manager for the Boathouse District’s mechanical contractor, Harrison-Orr Air Conditioning, LLC, Oklahoma City. “Most of the HVAC selection at Devon was definitely about achieving a discreet look. Trying to hide everything with a four-pipe system with a boiler, for example, would have been very hard. At the same time, energy efficiency was important.

There are event rooms that need to be heated, and also training rooms that need to be kept at 66 degrees all the time – receiving cooling even in the winter. Devon needed a system that would make economical use of consumed energy. Heat pumps with heat recovery offered the ability to zone properly given the diversity of the space.

With VRF identified as the preferred technology, the team then decided on Mitsubishi Electric for “the support. They’re always doing upgrades. They won’t leave you behind,” said Riggs. McClure added. Mitsubishi Electric products are great. We’ve done almost 3,000 tons of Mitsubishi Electric; I believe in them so much I have them in my home.”

Riggs described the installation process for Mitsubishi Electric VRF as “pretty quick. The condenser units go in good and clean, and the flexibility of the indoor units has let us do some unique things, like taking out soffits and putting units in there.” McClure has also been impressed with Mitsubishi Electric’s training offerings: “We sent several of our guys to training class in Texas a few months before doing the Devon Boathouse. The hands-on training is invaluable when working with VRF.”

For Riggs as an end-user, no specific training was needed.

“The system was simple to learn, in terms of using the controls. And the controls have been effective,” Riggs said.
The campus went on to use Mitsubishi Electric VRF on other projects. The second was for the Chesapeake Finish Line Tower, described by McClure as “a unique, cantilevered building — unique in terms of look and structure. It’s shaped like a triangle with five floors and a basement, and each floor is cantilevered off of the main structure. It has castellated beams, so we worked with the engineer to find a path for the ductwork through the beams’ holes. We also concealed the indoor units above the ceiling.”

The tower’s outdoor units also required a creative solution, as the architect did not want the outdoor units to be visible. They were placed in the basement, where they pull in natural outside air ventilation. In winter, they reject heat into the basement. In summer months, they reject heat to the outdoors. These practices keep the units running at peak efficiency.
Another project was the CHKI-Central Boathouse. It features a performing arts venue, art gallery and workout center. Similar to the Devon Boathouse, the CHKI-Central Boathouse created the HVAC challenge of having a big variety of heating loads and unique spaces.

“A range like that can only be done with this kind of system. So we used four Mitsubishi Electric VRF Systems for this boathouse,” explained McClure.

“One is a straight heat pump, with no heat recovery. That’s for the performing arts venue. The load in that space varies quite a bit, so we needed a system that could ramp up when there were lots of people and then ramp down when there was no performance going on. That space also had to be acoustically sound.”

Following the second boathouse project, the team began a new project, at the SandRidge Youth Pavilion. See the sidebar on this page for a complete listing of projects and systems used.

Mitsubishi Electric Equipment Installed In All Buildings:
RIVERSPORT RAPIDS:
8 PURY R2-Series Outdoor Units, 25 PEFY Ceiling-concealed Ducted Indoor Units, 3 PFFY Floor-standing Exposed Indoor Units, 1 PLFY 4-Way Ceiling-recessed Cassette Indoor Unit, 2 PVFY Concealed Vertical Ducted Indoor Units
SANDRIDGE YOUTH PAVILION:
1 PURY R2-Series Outdoor Unit, 6 PEFY Ceiling-concealed Ducted Indoor Units, 1 PLFY 4-Way Ceiling-recessed Cassette Indoor Unit, 2 LGH Lossnay Energy Recovery Ventilators
CHK | CENTRAL BOATHOUSE:
4 PURY R2-Series Outdoor Units, 3 PUHY Y-Series Outdoor Units, 15 PEFY Ceiling-concealed Ducted Indoor Units, 5 PLFY 4-Way Ceiling-recessed Cassette Indoor Units, 9 PVFY Concealed Vertical Ducted Indoor Units
CHESAPEAKE FINISH LINE TOWER:
6 PURY R2-Series Outdoor Units, 29 PEFY Ceiling-concealed Ducted Indoor Units, 2 PKFY Wall-mounted Indoor Units, 2 PMFY 1-Way Ceiling-recessed Cassette Indoor Units
DEVON BOATHOUSE:
8 PURY R2-Series Outdoor Units, 21 PEFY Ceiling-concealed Ducted Indoor Units, 1 PKFY Wall-mounted Indoor Unit, 33 PLFY Ceiling-recessed Indoor Units, 15 LGH Lossnay Energy Recovery Ventilators

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