The new 1,000-foot pedestrian bridge connecting students to the Utah Valley University (UVU) campus was in need of a consistent, reliable snow and ice removal solution that did not require salting or sanding surfaces or moving equipment across the structure. Aron Frailey, owner and chief mechanical engineer of Thermal Engineering, LLC, has decades of experience in hydronic radiant snow-melt systems, but he had never designed or installed a system for a 15-foot-wide (4.6-meter-wide) elevated expanse, suspended up to 35 ft (10.7 m) in the air.
To meet the challenge, Frailey needed piping solutions that would be durable enough for the harsh conditions, but also viable for his construction crew. As a longtime customer, Frailey looked to REHAU for the snow-melt loops of PEX piping embedded in the concrete pathway, selecting RAUPEX O2 barrier pipe for the job. As the main component in hydronic systems, this PEXa piping provides long-term strength, enhanced temperature capabilities and an extra layer of protection against oxygen permeability with its co-extruded ethylene-vinyl alcohol (EVOH) oxygen diffusion barrier.
“We’ve used REHAU pipe for a long time and never had any issues. It’s like second nature,” he said. “We know it. We know what to expect from it. We have had so much technical support and experience with REHAU.”
While Frailey has many years of successful projects using PEX for both radiant heating and snow and ice melting (SIM), this was Thermal Engineering’s first major project using polymer piping for distribution piping to the SIM loops, due to its vast benefits compared to working with steel pipe in this elevated application.
He collaborated with REHAU manufacturers’ rep Rocky Mountain Integrated Solutions, Inc. (RMIS) on the project design and material selection. Additionally, engineering consulting company WSP offered design expertise in consultation with the Utah Department of Transportation for the high-efficiency boiler plant and control systems serving the bridge, including NTI Fire Tube Giants (FTG) Boilers with a 2.2 million Btu capacity, Grundfos CR pumps and a Tekmar 680 control.
The design used 34,500 ft (10,516 m) of 5/8 in. REHAU RAUPEX O2 barrier PEX piping for the SIM loops. The PEX piping was fastened directly to the 6 x 6 bridge deck rebar at 6 in (16 cm) on-center spacing before being encased within concrete. The piping was connected to pre-fabricated manifolds that were installed within the bridge deck and accessible via access panels. The manifolds are supplied with a heated antifreeze solution through 1,900 ft (579 m) of 2 1/2 to 4 in (6 1/2 to 11 cm) supply and return piping.
Frailey helped design the manifolds and oversaw their modification and placement during installation. In total, Frailey fabricated seven 2 in (6 cm) custom copper manifold vaults to house distribution piping, using F1960 fittings for connections to SIM loops.