California Plant Saves Money and Drying Time With Radiant Heating

A ventilated building with a heated slab helps a California regional agency improve biosolids drying and reduce transportation costs.
California Plant Saves Money and Drying Time With Radiant Heating
After the hydronic heat tubing system was laid, the system was pressurized, the slab was poured, and construction of the metal building began.

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When thinking of radiant heat or hydronic snowmelt, most people envision warm floors, heated sidewalks and ice-free driveways. The Big Bear Area (California) Regional Wastewater Agency (BBARWA) had something altogether different in mind.

The agency had been looking to reduce the water content and weight of its biosolids, making the material less expensive to haul to an offsite facility. After trying several drying methods with marginal success, BBARWA (pronounced BAR-wa) decided to devise a new system that would be more effective and more efficient, and reduce odor complaints.

The agency worked with Viega Radiant Design Services to construct a ventilated drying building with a heated concrete slab floor. Viega Radiant Design Services completed the facility, which BBARWA personnel say has performed above expectations. In the first year alone, it saved some $200,000 in transportation and fuel costs.

Different twist

Viega had designed and quoted thousands of traditional radiant or hydronic heating projects, but none quite like what Big Bear planned. Fred Uhler, BBARWA plant manager, approached Viega’s radiant sales manager and district manager to discuss the concept’s viability. “I met the Viega representative; he thought outside the box and was able to get what I needed in an easy and economical way,” says Uhler. “Viega answered our call for this unique project.”

Since the wastewater treatment facility produces its own electricity using three natural-gas-fueled generators, the water flowing through the slab is warmed by the generators’ exhaust by way of a heat exchanger. Viega worked on the specifics of the slab heating system, focusing on how to generate enough heat from the slab to meet the biosolids drying objectives. Engineers used finite element analysis to determine the optimum tubing size, spacing and install depth in the slab, based on the water temperature supplied from the generator exhaust. The shape and size of the slab — 315 by 60 feet — made the project well suited for the Viega Climate Mat system, designed for applications larger than 10,000 square feet.

Simple install

Arriving on the job site in a preassembled roll, the mat came complete with temporary supply-and-return headers and tubing. Installation involved simply unrolling and securing. There was no concern about proper laying or spacing of individual lines. The mat system was pre-pressurized and numbered for accurate placement. The drying building also includes three fans (Big Ass Fans) to move moisture out of the building.

The 18,900-square-foot mat and distribution manifold installation was completed in less than one day with the labor of three workers. Uhler estimates that he saved three weeks of labor as opposed to installing conventional radiant heat tubing. “The representative was right there on the job site, working hand in hand with my guys,” says Uhler. “That’s how we like to work — we do things ourselves.”

With the mat and manifolds installed, the system was pressurized and the slab was poured; construction of the metal building began the next week. The system went into operation June 2014.

Unique solution

While many clean-water agencies use covered drying beds, BBARWA’s use of a heated slab is unique. Within a few months, it became clear that its application of radiant heating was successful. In 2015, Uhler reported that the system was performing beyond expectations and even better in the low-humidity winter months.

“This system is self-operational and I’ve had zero maintenance issues with the Viega product,” Uhler says. “It couldn’t be any better.” He reports that a number of other agencies are interested in the project, which received a California Water Association Desert Mountain Award for Innovation.

Uhler appreciated the support Viega provided: “Anything they said they could do, they did it. They were top-notch guys, from the sales staff to the design support. They were excited about the project. It’s great to work with people like that.”


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