California wastewater agency wins with radiant technology
When most people think of radiant heat or hydronic snow melt, the usual applications come to mind: warm floors, heated sidewalks and snow-free driveways. But occasionally, Viega Radiant Design Services in Nashua, NH, receive requests for assistance with some out-of-the-box projects.
The Big Bear Area Regional Wastewater Agency (BBARWA pronounced bar-wa) in Big Bear, CA, contacted Viega Radiant Design Services with a project that needed an innovative solution.
A byproduct of the water treatment process is sludge, which is composed of 25% solids and 75% water. Since the sludge must be hauled by truck to an off-site disposal area, BBARWA had been looking for a way to reduce the water content and weight of the sludge, making it less expensive to haul. BBARWA had tried several different methods to dry the sludge with only marginal success, so they decided to devise a new system that would be more effective, more efficient, and would reduce the odor complaints.
Based on the idea of an enclosed building with a heated slab, a new concept began to take shape. BBARWA Plant Manager Fred Uhler contacted a Viega Radiant Sales Manager and District Manager to discuss the viability of the concept his team devised − an enclosed, ventilated building with a heated slab for the sludge to dry on.
Since the facility produces its own electricity using three natural gas generators, the water flowing through the slab would be heated with a heat exchanger in one of the generator's exhaust, making it an efficient co-generation system. Within the first year alone, the new system saved approximately $200,000 in transportation and fuel costs.
Viega Radiant Design Services worked on the specifics of the slab heating system design, focusing on what would be required to generate enough heat from the slab to meet the sludge-drying objectives. Viega design engineers used finite element analysis (FEA) to determine the optimum tubing size, spacing and install-depth in the slab based on the water temperature supplied from the diesel generator's exhaust.
Due to the shape and size of the heated slab – 315-foot-by-60-foot − it was clear that this project was an excellent application for Viega's revolutionary Viega Climate Mat system, best for applications over 10,000 square feet. Viega also recommended using fans to move moisture from the building, in addition to the heated slab.
Installation of the Viega Climate Mat and distribution manifolds was completed in less than one day. Typical radiant heating and cooling installs call for 2,500 square feet of radiant tubing to be laid in one day, but with the Viega Climate Mat, contractors can plan on laying 25,000 square feet a day with the labor of three men in both cases. BBARWA called for 18,900 square feet and it was installed in one day. Uhler estimates that he saved three weeks of labor installing the Viega Climate Mat.