It does not necessarily apply to HVAC system design, at least not for McGrath Refrigeration, Knox, Ind. Company owner J.D. McGrath knows that some things, like the laws of physics, are what they are, but he also knows that other things can grow from unexpected sources, opening up new possibilities.
For instance, McGrath met Dr. Byron M. Holm, a family practitioner to the Plymouth community, and his wife, Mary (a registered physical therapist), when the doctor called the contractor to design a residential geothermal system for his daughter’s home. As the discussion evolved to efficiencies and comfort control, McGrath wound up suggesting that a ductless mini-split system would be a better solution.
Well, this doctor has a mechanical aptitude. He got it, and he liked it. “The doctor is a highbred,” said McGrath. “He is a mechanically inclined and a very intelligent person.” (Editor’s note: Aren’t these the best doctors to have, really?)
“He’s a hard worker and very energy-efficiency consciousness. He wanted us to put a price on the geothermal project for the home. He then asked me to meet him and his daughter for breakfast one morning. The four-pipe system on the table “isn’t the most efficient but it would do to the job,” said McGrath. “I told him to check out what Mitsubishi had to offer.”
The good doctor also had dreamed for 32 years of a one-stop wellness, health care, and medical fitness center - a “LifePlex” - for wellness promotion, state-of-the-art diagnostics, and rehab that is not a hospital. This dream came to fruition with the 2007 grand opening of the center, which encompasses 143,000 square feet on two floors and includes the Holm Medical Clinic, Fitness Forum, centers for specialty orthopedics, nephrology (kidney dialysis and treatment), cardiac rehabilitation, screening and diagnostic X-ray, speech therapy, diabetes counseling, and nutritional services. It also houses leased office and retail space, a café, pharmacy, and a daycare center.
Guess who got the job for the LifePlex’s mechanical system. And guess what he installed there, after much design upfront.
“J.D. and I had just got back from a Mitsubishi training class in Atlanta,” said Paul Quigley, then at Excelsior Mfg. & Supply Corp., now with Goodman Manufacturing as the Midwest regional director.
“J.D. found himself talking to the doctor about HVAC applications. The doctor said, ‘Could you look at my project,’ which was originally designed with boilers and chillers. It just evolved from there.”
According to Quigley, the entire facility was a work in progress from the onset. “When the center was built, the tenants were not all secured. We had no idea who would be occupying the space and what their ultimate needs would be, since so many of the areas were originally designed for construction skin load only.”
The ductless system “provided us with an extreme amount of flexibility for add-ons, equipment changes and relocations, walls moving, etc.,” he said. “One of our larger skin load designs ended up as a nephrology care center that needed variable-temperature capabilities. Once the design for that was finalized, we had less than 20 days to finalize the design and completely install the system, which wasn’t a problem.”
DETAILS IN DESIGN“The real work is in the design, 100 percent,” said McGrath. “Having multiple people working on the design is the way to go, absolutely.” Some of the ideas he and his cohort had came from spending nights burning the midnight oil, scouring the LifePlex blueprints.
“Paul and I came up with phenomenal designs and layouts, working early in the morning to late at night. We really enjoyed the opportunity. We never expected any publicity,” he added. “We just wanted to be able to walk up one day and say, ‘I did this.’”
The first part handed to them was the gymnasium. “This is very simple stuff, very basic to the HVAC industry,” he said. “It’s full-size, college NCAA size; the Chargers play there. We designed the airflow velocity. There is literally less than 1° difference from the wooden floor to steel ceiling, 30 feet. Walking from one corner of the gym to the other, we were so impressed.” Their manufacturer consultants were also impressed. “This worked? You guys really did this?”
The gymnasium is a modified, open-concept, two-story complex with a complete running track elevated on the circumference of the second story. The McGrath/Quigley team designed a system that absorbed the stratified heat on the second level and shifted it to lower-level units, calling for heat on the first level via energy recovery through the refrigerant in each R2-Series system. Outdoor air was introduced via four 1,200-cfm Lossnay® energy recovery ventilators (ERVs), which were tied into the building’s comfort control system.
Other areas, including the aerobics center, the racquetball courts, the fitness center and several offices, were treated with a combination of one-way and four-way concealed-recessed cassette indoor units, ductless wall-mounted indoor units, and various ducted indoor units. The center also was designed with a combination of indoor units integrated with Lossnay ERVs for ventilation air. All 243 tons are controlled by Mitsubishi’s TG2000 Integrated System Software.
“For a system of this magnitude, I can’t say it worked flawlessly,” McGrath continued. “But really, the installation side of it was really simple, once you know what you’re doing. The overall project is not time-consuming like a large boiler system. My lead tech does all the high-end stuff; he loves to learn the new technology himself. We’re still working out some computer bugs, problems with exactly the way we want things to work.”
There never is a perfect path. “I’ve learned a lot, through Mitsubishi’s help, our own time spent, and the doctor’s help. One time he stayed at the facility all night.”
Some design changes were necessary, not because the original computations were wrong, but because the facility became more popular than the owner had anticipated. A room for an exercise class called spinning (think exercycles on speed), for instance, was anticipated to have class sizes of eight to 10; in actuality, they’ve been spinning with 13-15 in the class.
“At first we thought the system was underperforming,” said McGrath. “Then we double-checked the numbers.” Classes were also being held closer together, so the system didn’t have as much time to recover. “We beefed the system up.”
Aerobics had the same thing happen. “They underestimated the interest.” The entire facility started out with 1,500 clients before the doors even opened; there were 3,700 within a year of opening.
The dialysis/nephrology area design is another example of how the system evolved with input from others. The problem that needed to be solved there was that the patients, whose blood was essentially being cleaned, were colder than the nurses, who were moving around a lot.
“When we first designed the project, we had really individualized zone areas. Each couple of patients had a zone,” McGrath said. Then economics forced them to scale it back a bit. “In one large, 3,000- to 4000-square-foot area, we keep all the cooling on the nurses, and keep low air movement in the patient area. It is zoned four times in that area.”
“We put air handlers in the same room, cooling and heating simultaneously,” said Quigly. “If one area’s calling for cooling, we move the superheated air to the section calling for heating. It’s unique to this certain application. Most will reject unwanted heat to the outdoors. This one transfers energy from the refrigerant. The BC controller is the brains behind it,” he added. “All of the units are tied into the BC controller.”
SPECIAL SYSTEMSEven though the Mitsubishi system is a heat pump, there is no backup heat in the whole facility. Local codes do not require it. “There have been some concerns in nephrology: What if the system failed? They’ve hinted around for some type of auxiliary system. We’ve only got one condenser that takes care of this area,” said McGrath. For emergency purposes (not a temperature-initiated backup), they may install electric resistance heat via inline duct heaters.
The pool rooms, or natatoriums, are the only areas that do not use the mini-split design, and that was due to the corrosive environment. “We wished we could have used it,” said McGrath. “There would have been so much free heat.”
The mini-split system’s inverter technology varies the speed of the compressor in the outdoor unit to meet changing load requirements in each of the indoor zones. The City Multi system is able to distribute capacity, simultaneously cool and heat (R2-Series only) over two pipes, and provide temperature control in every conditioned space.
The system is actually oversized in order to meet the geographic area’s winter climate, but this does not affect its ability to cool effectively. “There is no additional dehumidification for gyms,” said Quigly. “We were able to take care of all the latent loads real easily. In northern Indiana, it’s almost unheard of - it was designed for cooling real easily, but had to be designed to run in winter entirely off the heat pump.
“We were able to significantly oversize for heating,” he continued. In summer, “we’re running compressors down to 16-20 percent of their capacity. We’re running 20-ton systems at only 7 tons of usage. The amount of condensation we get out of these is amazing. Once they achieve that setting, they run at such a gentle flow, it pulls out gallons a day.”
The natatorium, of course, does not work through the same system, but the rest of the building adjoining it reaps the benefits of removing that latent load. The aquatic center uses a standard dehumidification system from Dehumidifier Corp. of America.
LONG-TERM CAREMaintenance for the facility is being done by a person hired at the facility. In addition to the equipment (condensate drain pans, filters), he also runs the cleaning crews, takes care of lighting, heating, “everything in the facility,” said McGrath. “Nephrology is privately owned. They maintain their indoor filtration systems. The LifePlex team takes care of outdoor condensing units.”
The system’s G-50A centralized controllers provided access to every indoor unit in the entire facility from a single centralized location. In addition, some occupants were given simplified controls in their areas for fine-tuning, and other occupants were given access on their desktop computers to control the comfort in their environment.
By using this technology, Holm was able to obtain a sizeable tax credit and discounted utility rates. In addition, the G-50A centralized controllers allowed Holm to use tenant billing, which monitors energy usage for each zone being conditioned by City Multi systems. This capability, in conjunction with Watt-hour Meters (WHMs), generates a monthly statement so Holm can bill each tenant a usage based upon apportioned energy consumption.
The cost of the total project was estimated as high as $18 million-20 million, McGrath said. “It’s an overwhelming facility. We’re now calculating the utility bills.”
According to Quigley, when the City Multi systems at LifePlex were recently monitored, outdoor temperature reached 96°F and the building was at full occupancy. Reports show the systems were running at a cost well below the industry standard.
“Mary and I are convinced the role of traditional medicine must change,” Dr. Holm said. “This new wave must focus on prevention and early detection, and there you have the perfect description of our LifePlex - a medical component on one side, a wellness and fitness constituent on the other. Supporting this vision, the City Multi solution has become an ideal complement and partner.
“When you are in an exercise class, you want to feel the air move. The ERVs do that extremely well, and we have had nothing but happy customers who enjoy the comfortable exercise environment the systems provide. The equipment is already paying dividends, not only in discounted electric rates and energy savings, but in the happiness (wellness) quotient from everyone in our new facility,” Holm concluded.