- The project design called for two zones for each apartment and one zone for each common area per floor
- Thermal Engineering installed two HTP Elite high efficiency 399,000 Btuh dual condensing boilers
- Thermal Engineering installed two HTP SuperStor Ultra indirect storage tanks to supply domestic hot water
- The boilers are piped primary/secondary with two Grundfos Magna3 variable speed pumps on the secondary loop
- A reverse return distribution system of 1½-in., 1¼-in., 5/8-in. and ½-in. Rehau RauPEX PEX piping runs to three Viega manifolds for each side of the project
- To control the entire mechanical system, tekmar controls with remote sensors were installed
PARK CITY, UTAH — The area is home to some of the most popular ski resorts in the country — Canyons Resort, Deer Valley Resort and Park City Mountain Resort — and plays host to the United States Ski Team and is the main location of the Sundance Film Festival. At its peak season — from November to March — Park City’s tourist population far exceeds the permanent resident population.
Instead of trying to locate housing for its temporary labor force, the municipality of Park City decided it would be beneficial and more cost effective to house its own various transit department employees with the construction of the Park City Transit project, a 7,600-sq.ft. apartment complex, which includes 13 studio apartments — six second floor, six third floor and one ADA ground floor — a first-floor common garage and common foyers, all independently zoned for hydronic baseboard heating.
“The facility has several studio apartments, and the design requirements called for an efficient structure to house the increased labor force as needed. Additionally, the units had to have their own heating ability,” says Aron Frailey, owner and manager, Thermal Engineering, a mechanical engineering firm and contracting company dedicated to the design and installation of hydronic heating and cooling systems located in nearby Draper, Utah.
Frailey has an impressive background with years of hands-on construction experience, including an emphasis on radiant heating systems. A graduate of Utah State University, Frailey has a Bachelor of Science degree in Mechanical Engineering and a Master’s in Business Administration. The engineering services Frailey provides are enhanced by his experience with hand-on installations. He holds an active boiler installer contractor license and has worked on a variety of projects, many of them receiving national recognition in both simplicity and design innovation. Aron also works with his business partner and brother Coy Frailey on many projects.
Inside the studios
The small per square footage area of the rooms, coupled with the number of units, makes for a dynamic heating load. The project design called for two zones for each apartment — the bathroom and the living area — and one zone for each common area per floor, which, in total, equaled 13 zones per floor.
At any given time, several rooms could be calling for heat all at once or just a few at a time. Therefore, the mechanical system needed to be capable of a wide range of operation.
For the heating system, Frailey and his crew installed two HTP Elite high efficiency 399,000 Btuh dual condensing boilers, which feature up to 96% thermal efficiency and a combustion turndown ratio up to 5:1.
For domestic hot water use, Thermal Engineering installed two HTP SuperStor Ultra indirect storage tanks to supply domestic hot water to the structure, which was later piped by Yeagle & Sons Construction, Salt Lake City, the plumbing contractor on the project. The SuperStor Ultras draw energy from the boiler and hot water flows through the internal heat exchanger in the tank, heating domestic water. The installation also uses a Spirotherm air scrubber with an expansion tank and glycol fill tanks.
The boilers are piped primary/secondary with two Grundfos Magna3 variable speed pumps on the secondary loop. Grundfos’ Magna3 is an energy-optimized, variable-speed wet rotor circulator with adaptive intelligence that will cut power consumption by up to 85% when compared with conventional circulators.
“We used dual condensing boilers and variable speed pumping with zone valves to each room to scale to the load as needed,” says Frailey. “If only a small load is present, the pumps will run at a minimal speed. Under heavy load conditions, the pumps and boilers can deliver the needed flow requirements.”
Satisfied with the ability of variable speed pumping technology, “the Magna3’s ability to develop an optimal pump capacity over time by learning the systems is very appealing,” says Frailey. “What sold us on the Magna3 selection was that the pump is very efficient in its power usage and its ability to run at a wide range of flow rates.”
Frailey also lauds the fact that the Magna3 provides an abundance of information that can be supplied to the building management system. “When considering the engineered specified pumps compared to the Magna3, the owner will easily realize a return on the initial cost investment,” notes Frailey.
Frailey ran a reverse return distribution system of 1½-in., 1¼-in., 5/8-in. and ½-in. Rehau RauPEX PEX piping to three Viega manifolds for each side of the project. Using the manifolds with flow and balancing, Frailey ran a single distribution line from the manifold to the zoned Runtal radiators, which are hung low on the wall in each apartment, bathroom and common space.
The manifold had all the flow control and thermal actuators to individually control each zone. “Think of the project as split in half,” says Frailey. “The installation consisted of three levels on the north side of the building and three levels on the south side.”
Controlling dedicated spaces
To control the entire mechanical system, tekmar controls with remote sensors were installed. Since each apartment was individually zoned, the system needed to be secure. Each room has a dedicated tekmar wall sensor — which is flush mounted with the wall’s sheet rock — to read the temperature of the dedicated space.
The tekmar controls send 0-10V signals to the two boilers and modulate the water temperature based upon outdoor reset and indoor feedback. However, the thermostats are located in the ground floor mechanical room, so tenants can’t compromise the system. As needed, the rooms can be adjusted by the building management system.
Keller Construction, Salt Lake City, the GC on the Park City Transit apartment complex, reports that the city is content with the project.
Since its inception in 1945, Grundfos has flourished from one small factory in Bjerringbro, Denmark to a global corporation comprising more than 80 companies and over 18,000 employees. This year, the company celebrates its 40th anniversary in the United States. In North America, Grundfos employs more than 1,600 people – 1,300 in the U.S. alone. In addition to pumps, Grundfos produces standard and submersible motors as well as electronics for monitoring and controlling pumps.
High on the company’s agenda is an active commitment to improving the environment. Grundfos contributes to global sustainability by pioneering technologies that improve quality of life for people and care for the planet. For more information, visit www.grundfos.us.