When Steven Bowman came on board at Tarleton State University, a member of the Texas A&M system, one of the biggest challenges awaiting him was expanding the growing university's HVAC system. It quickly became an urgent project for the new Director of Energy and Utilities Operations, as the existing central boiler plant had to be shut down or repaired on six different occasions during Bowman's first year alone. After installing four AERCO Benchmark 3.0 Low NOx (BMK 3.0LN) boilers in January 2008, Bowman has delivered the reliability and redundancy the university urgently required. The new system has also helped the school realize an impressive 64.1% reduction in natural gas usage.

After measuring and evaluating the overall system's operating parameters, Bowman recognized that the root of the problem was the ten-year old Scotch marine-style boiler plant. "We had a condensing system without a condensing boiler. On average, the 350 hp winter boiler provided 150° F supply water, which typically returned at just 120º F. Because the equipment was not built with stainless steel materials, it was unable to handle the condensing operation and quickly became a maintenance nightmare. Plus, the 100 hp 'summer boiler' offered no real redundancy."

With no true back-up, the numerous repairs had to be made immediately - often during off-hours, which meant higher labor costs. This scenario only confirmed Bowman's opinion that the new system needed to subscribe to his N+1 philosophy.

The search for condensing boilers that could handle the system's high ΔT design naturally led Bowman to AERCO, recognized as the leader in condensing boiler technology. John Neal, Jr., AERCO's manufacturer's rep in Texas, and Bowman visited Tarrant County Community College. Bowman also spoke to representatives from Dallas-Forth Worth International Airport and Texas Tech University, both of which are Neal and Associates customers. All of these locations use AERCO Benchmark boilers and Bowman was impressed with their operations.

After a thorough evaluation, Bowman selected four BMK 3.0LN boilers, each delivering approximately 90 hp, for the central plant at Tarleton's Stephenville campus. The condensing boilers also feature 15:1 turndown - a marked improvement over the 3:1 burner turndown of the pre-existing equipment. According to Bowman, the combination of effective condensing and robust modulation has improved the system's efficiency from 48% with the old boilers to 91% with the AERCO units.

More savings can be expected if the AERCO BMS system is added, which is being considered for the project's next phase. With the integration of the multiple unit controller, the system will be able to match any load from 200,000 to 12 million BTU/hr. without wasteful cycling or temperature overshoot. In addition to providing improved efficiency, the four boilers give the new system the redundancy Bowman determined was necessary.

The Benchmark series offered flexible venting options and eliminated the need for primary/secondary piping, which simplified and expedited the installation. "We needed to move quickly because we wanted to get the new AERCO boilers installed for the 2007-2008 heating season," explained Bowman. "As of the New Year, the system was fully operational and providing heat to four buildings on campus."

The installation of the four BMK 3.0LN units was the first phase of a $15 million project that will significantly overhaul the university's HVAC infrastructure. The project is being done to improve efficiency as well as accommodate the construction of a new nursing school building on campus. Bowman plans to replace a steam heating loop on the campus and will install new chillers as well as run new piping throughout the campus. Another eight Benchmark units are scheduled to be installed by the end of the summer 2009.

The initial results have Bowman excited about the savings the university will realize when the project is completed. "Our goal was 30% improvement but our initial savings have been well above that. Once the project is complete and we fine tune everything we will probably even go above our initial numbers."

In fact, Bowman has been so impressed he is forwarding the preliminary results to other universities within the Texas A&M system. He believes high ΔT systems with condensing boilers such as the BMK 3.0LN and the benefits they bring will be of interest to fellow operations managers.