How do two boilers, both working at the same time, consume 28% less energy than a single boiler working by itself? The answer lies in design and precision controls.

When constructed in 1983, the facility housing the Cuyahoga County Board of Mental Retardation and Developmental Disabilities (CCBMRDD) in Maple Heights, Ohio installed a single, large flex tube boiler to handle the space heating burden. This boiler, which utilized a flexible bent water tube design to prevent thermal shock failure, achieved its mission and was a reliable cornerstone to the heating system. However, it was not very efficient, and as a result, the CCBMRDD operations department, which handles all maintenance for the building, looked to AERCO for a better solution.

“In the fall of 2000 we installed two 2.0 million BTU/hr. Benchmark boilers to replace the single flex tube unit,” said Ronald Rupert, engineering sales at C.J. Michelson Company. “Built to withstand thermal shock, the condensing and modulating units can deliver up to 98% thermal efficiency and have shaved significant costs from the bottom line. Also, because there are two of them, they provide the facility with 100% redundancy.”

The Benchmark boilers are tied together and regulated by AERCO’s Boiler Management System (BMS) to operate as a single entity. The BMS gives each unit precise firing instructions, regulating the boiler plant and taking full advantage of Benchmark’s modulating design.

“The old flex tube boiler either fired at 100% or it was off. A 2.0 million BTU/hr. Benchmark can run with as little as 100,000 BTU/hr. (just 5% input) and will gradually increase capacity – in precise 1% increments – until it’s firing at 100%,” said Rupert. “In fact, the lower the firing rate, the better the Benchmark’s efficiency, so the BMS regulates the two units to share the load. Both AERCO condensing boilers running at low fire consume less than the old, single flex tube boiler running alone. There’s very little wasted energy.”

When comparing natural gas usage figures for January, February, and March of 2000 with the same months during both 2001 and 2002, the Benchmarks show themselves to be much more energy efficient despite slightly colder winter temperatures.