Case Studies

Apartment Complex Combines Heat and Hot Water

Publish Date: 04/2004
Products and Technologies

Six Benchmark units serve Central Towers’ heating and domestic hot water needs.
"In all the time the AERCO units have been in operation, we've yet to tap into our redundancy reserves." - Chuck Gressler, Building Superintendent

“One day last winter, the temperature hit minus 10°F,” said Chuck Gressler, building superintendent at Central Towers Apartment Building. “On that day, we heated this entire 2.5 million sq. ft. apartment complex on just four AERCO boilers. That’s impressive.”

The original 32.0 million BTU/hr. heating system at the Central Towers Apartment Building, located in Albany, New York, consisted of two huge, steam-fired boilers. In September 2002, the old worn-out heating system was dramatically overhauled, with the old units replaced by only six 2.0 million BTU/hr. Benchmark boilers – a 63% reduction in plant capacity.

“Our existing heating plant had been greatly oversized to compensate for the inefficient performance of conventional equipment and the greater need for emergency backup with only two boilers,” said Gressler. “We knew that modular boilers were the logical replacement, but it was the energy savings derived from the Benchmark’s high-efficiency design that made us decide to go with AERCO. The fact that AERCO’s multiple unit controller fit right into our building management system was an added bonus.”

Four of the six Benchmark units are used for space heating. The remaining two are dedicated to the building’s domestic hot water load, although they are never used in tandem. Rather, they are employed on an alternating basis so that one of the two units is always available to provide redundant support for the space heating plant. All six units are connected to AERCO’s Boiler Management System (BMS) to maximize the performance of the plant as a whole, modulating output to precisely match changing demand on the heating system throughout the day and year.

“The AERCO BMS plugged easily into our own building management system,” added Gressler. “The BMS hooks the boilers into a heat recovery system, which is located on the roof of the building, and adds to the overall efficiency of the system.”
The Bottom Line
18% Savings on Energy Bill

Energy costs at Central Towers have decreased since the AERCO system was installed. When comparing gas consumption from September to December of 2001 to the same months in 2002 (after the building was converted to AERCO), usage decreased by more than 9%.

“Our total gas bill decreased by more than 18%. And on that cold, minus 10° day, the four boilers ran at 95% capacity,” said Gressler. “In all the time the AERCO units have been in operation, we’ve yet to tap into our redundancy reserves. Albany can have some cold winter days, but with the units usually running at 45%–50%, our heating system is more than an efficient, cost-effective match.”

Comparison of Gas Usage and Expenses for
September–December Period
  Gas Used (Therms CCF) Gas Bill
2001 Original System 39,952 39,170 $5,272.09
2002 AERCO System 36,072 35,550 $4,346.83
Difference 3,880 3,620 $925.26
Savings 9% 18%

Comparison of Average Daily Temperatures for
September – December Period
  2001 2002
September 61°F 63°F
October 50°F 46°F
November 43°F 37°F
December 33°F 26°F