Ground-source heat pumps will heat, cool entire apartment complex

Feb. 10, 2014
Throughout the building, Bosch water-to-air heat pumps are tucked away in closets, and pull water from the supply lines. Each apartment has its own heat pump. Two circulators are used per building. A Wilo Stratos handles the circulation of the indoor loop, while a Top S circulates the ground loop. All bore-holes are five-inches in diameter, with one-and-a-quarter-inch pipe.

BRIGHTON, COLO. — One of Colorado’s largest geothermal projects is soon drawing to a close. When finished, Solaire Apartments, in Brighton, Colo., will be entirely heated and cooled by ground-source heat pumps.

Solaire Apartments plans to duplicate the new geothermally-conditioned complex in other towns across Colorado.

The 252 unit, 12-building complex uses 112 wells to provide 326 tons of heating and cooling capacity.

The up-front premium associated with a ground-source system hasn’t made them popular with property owners in the rental business, but the owners at Solaire see the value, and they’re sure it’ll pay off.

 “While the first costs of installing geothermal to serve the Solaire residences was more expensive than conventional HVAC, the ability to eliminate a portion of the per-unit energy costs makes our community more affordable for residents,” said Brock Vinton, developer of Solaire. “As energy costs rise in the future, we believe that the sustainable aspects of Solaire will help us in tenant retention and overall cost competitiveness in our marketplace.” 

Vinton hopes that the Solaire project can serve as a blueprint for the development of other sustainable communities in Colorado and beyond. Key aspects that made the project feasible were the combination of power company and municipal incentives as well as partnering with reputable companies such as SMC Geothermal, the company that designed and installed the geothermal systems there.

The right dollar sign

If positive past experiences with a mechanical contractor aren’t enough to win a job, a low bid might help; especially one that comes in $2.5 million under the competition. Those were the determining factors that got SMC Geo the work at the new apartments just 20 miles north of Denver.

“I designed the geothermal system from the ground up; no pun intended,” said Conald Frank. He owns SMC Geothermal, a strictly-geothermal design and installation company. In 1998, he started the firm, naming it after what was most important to him; children Sarah, Melissa, and Christian – who at the time was still on the way.

Conald Frank, owner of SMC Geothermal, uses the Triton system to fuse a dry-fitted joint at Solaire Apartments, in Brighton, CO.

Frank’s broad construction background gives him an edge when it comes to envisioning an installation. With his complete re-design of the system; the exchange field went from one big community loop to 23 individual loops – two for each apartment building, and one for the clubhouse.

But to come in $2.5 million under the competition, it took more than a redesign. He also removed DHW production from the plan, and used a different pipe fusing method, which would save him countless hours and plenty of back pain.

The right combination

Instead of grouping each bore-hole into one massive district loop that feeds all the buildings, Frank’s approach was to bundle the holes by building, and use numerous, small pumps.

He explains that the modular approach is better for energy efficiency and reliability; efficiency because of staged pump operation according to the call, and reliability because of the ease of finding small replacement pumps as opposed to large ones.

Since there’s a mix of apartment sizes — ranging from one- to three-bedroom floor-plans — not all buildings have the same load. Each building is, however, one of three blueprints; plan A, B or C. The plan C buildings have 330-ft. deep holes. Plan A and B utilize 10 wells at 360’ and 390’, respectively. 

“There are two sets of five wells for each of the 11 apartment buildings,” explained Frank. “As the two-inch supply lines enter the building, they merge into a three-inch hydro-separator. On the other side, they split back to dual, two-inch lines once again; one set for each half of the building.”

Throughout the building, Bosch water-to-air heat pumps are tucked away in closets, and pull water from the supply lines. Each apartment has its own heat pump. 

Two circulators are used per building. A Wilo Stratos handles the circulation of the indoor loop, while a Top S circulates the ground loop. The independent loops are divided by the hydro-separator. The loop field runs when there is more a than three-degree difference between the two loops. 

All bore-holes are five-inches in diameter, with one-and-a-quarter-inch pipe. To ensure the quality of exchange field work, Frank hired a subcontractor he’s familiar with, Can-America Drilling Inc.

The right system

From the beginning, Frank knew SMC Geo was ready for the big project, but as a three-person firm, he knew they’d have their hands full fusing HDPE distribution pipe inside the building.

All the two-inch lines feeding the heat pumps needed to share space with ductwork, electrical, and plumbing lines. There’d be no shortage of cramped joist bays to deal with.

Being able to fuse pipe in tight joist bays and corners is an advantage provide by the Triton fusion system.

“After a day of socket iron-fusing two-inch pipe, my arms literally hang at my sides like Jello,” said Frank, who’s 56. “Especially with two-inch pipe, you have to push so hard, and it always takes two people. With 12 buildings to fuse, I knew we needed to try something new.”

“Wayne Arde, owner of Can-America told me about the Triton HDPE fusing system after seeing it at the International Ground Source Heat Pump Association (IGSHPA) convention last year,” Frank explained.  “It caught my attention, and I was eager to give it a fair trial.”

Steve Kroh of Shamrock Sales in Denver was on site during two days of fusing, and made several other trips to the jobsite to ensure that SMC Geo was acclimating to the new fusion method.

The Triton system is the HVAC industry’s first application of radio frequency (RF) electromagnetic technology; a method of welding plastic pipe that’s been long trusted in industrial applications. 

Radio frequency energy is emitted from the system’s portable control unit, and literally “excites” a thin strip of reactive metal that’s molded into each Triton fitting. The material heats up to the point of melting the pipe and fitting together to form a joint that’s stronger than either the pipe or fitting alone.

With standard socket iron-fusing, two pieces of pipe are individually melted, then pressed together and allowed to cure. The Triton system allows the user to dry fit the pipe and fitting together, position them as desired, then simply clamp the fuser tool around the fitting to complete the weld.  

“The Triton system not only takes a huge physical strain off of the installer, but one guy can fuse by himself,” said Frank. “Usually, it takes two people; one to hold the pipe while another holds the iron. It also eliminates the risk of burns, which is a reality for anyone fusing pipes with an iron.

The ability to dry-fit the joint before fusing makes it much easier to work in and around joist bays. In addition to the ease of use, the system also eliminates harmful fumes. 

According to Frank, Triton really shines in mechanical rooms, where the majority of the fitting are. “I’d say that the triton system saved me roughly $1,000 per mechanical room,” said Franks.  

Before being adapted for the piping industry, radio frequency fusion welding was designed for a range of plastic welding applications including industrial vessels, biomedical devices and consumer products where the integrity of the joint is critical.

More work

“We’ll be wrapping up Solaire’s Brighton project shortly after the New Year, but that is just the launching point,” said Frank.  “They’re planning to duplicate this project several more times in Colorado.”

As smoothly as the geothermal installation has gone, and with Frank being the system designer, Solaire has SMC Geo slated for the upcoming projects.  Frank’s son, Christian, just hopes the indoor fusing portion of the work takes place over the summer months.

At 15-years-old, Christian helps Dad on the job when he can. He aspires to be an architect or an engineer. In either profession, the time spent on the job will give him an edge when it comes to seeing the “bigger picture,” and how building systems integrate for efficient construction. 

And speaking of “bigger picture,” that’s just what Frank and the folks at Solaire are hoping the world sees through the use of affordable, sustainable technology applied to rental housing.

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