“For more than 25 years, we relied upon two huge cast-iron boilers to get us through the harsh New England winters,” said Gary Persechetti, supervisor of Building and Grounds for Chelmsford High School. “When they gave out, it would have cost more to repair them than to replace them. A contractor from one of our construction projects introduced us to AERCO, who demonstrated the benefits of a modulating and condensing boiler.”

Persechetti was impressed by the demonstration and in 2000 ordered five gas-fired Benchmark units from AERCO to support the school. Not only did the 10.0 million BTU/hr. boiler plant occupy less space than just one of the cast iron boilers, AERCO’s condensing design made it possible to eliminate all secondary pumps and associated controls, wiring, piping and valves, which streamlined the school’s overall heating system.

By extracting latent energy from water vapors created during combustion, AERCO’s condensing design proved to be significantly more energy efficient than the conventional equipment. AERCO’s Boiler Management System (BMS) coordinates the operation of the five Benchmark units. It provides each unit with firing instructions that ensure the plant’s maximum efficiency as it deals with fluctuating loads throughout the day. The plant operates on the simple principle that it requires less energy for a group of modulating boilers, each firing at “part load” to heat a building, than a single boiler operating at “full fire” to carry the entire workload. The ability to operate the AERCO boilers at lower water temperatures allowed Chelmsford High School to implement an indoor/outdoor temperature reset schedule to further enhance the system’s efficiency.

Energy costs at the high school have decreased significantly since the AERCO system was implemented. During the first year of operation, 2000–2001, Chelmsford reduced fuel consumption by 33% from the previous year.

“Our lower fuel consumption saved us $81,000,” said Persechetti. “Because of the results that AERCO showed in their first year at Chelmsford High School, we’ve installed Benchmarks at three additional schools. They’re everything you want in a boiler – efficient and self-reliant.”