The mechanical rooms in five of the school district's facilities were equipped with new Lochinvar® high-efficiency boilers. The heating and cooling systems were upgraded at Collins Elementary (built in 1957; 50,985 sq ft), Northern Hills Middle School (built in 1975; 112,012 sq ft), Central High School (built in 1986; 259,356 sq ft), the administration building (built in 1957; 23,258 sq ft), and the community aquatic center (built in 1990; 37,900 sq ft). The previous boiler systems, comprising multiple units with varying capacities, were 15 to 35 years old.

When size matters

The most challenging part of the new boiler system design was the overall size of the units, which was a critical factor in each of the installations. The Central High School mechanical room was originally designed with 13 units that have now been replaced with six Lochinvar Power-Fin® boilers. Collins Elementary School installed two Power-Fin boilers; Northern Hills Middle School was renovated with three Power-Fin boilers; the administration building was retrofitted with two Copper-Fin II® boilers; and the community aquatic center installed two Copper-Fin II boilers.

"The compact size of the Lochinvar boilers definitely aided in the installation, especially the Power-Fin boilers at Collins Elementary School and Central High School," explained Robert Gengelbach, P.E., senior mechanical engineer with URS Corp. Because of its vertical chassis design, the Lochinvar Power-Fin boiler fits in less than six sq ft of floor space.

Operating efficiency was another key factor in choosing the products. The Power-Fin models operate at an 87% thermal efficiency rating, which means 87 cents out of every fuel dollar are used to create heat. The Copper-Fin II models operate at an 84% thermal efficiency rating.

Recognizing the importance of installing an energy-efficient system, Lochinvar sales representative Paul Hedlund recommended using the Harmony™ Sequencer on the Power-Fin boilers and Heat-Timer® controls on the Copper-Fin II units. The sequencer precisely matches the infinitely proportional firing rate of the Power-Fin with the fluctuating demand of the system, optimizing system efficiency and reducing boiler cycling thus saving product life and fuel dollars.

At the time of the boiler system upgrade, the Forrest Hills district also made several system upgrades that have contributed to the increased energy savings. Enhancements include unit ventilators in each classroom, new windows, a lighting system upgrade from T12 to T8, enhanced EMS, and controls upgrades utilizing night setback and zone control.

23% decrease in fuel consumption

Winter 2002-03 was the first heating season for the new boiler systems, and even with the building expansions, Langerak has seen significant energy savings compared to last year. "We've had a cold winter this year and have considerably increased the amount of fresh air [15% to 20%] introduced to the building each morning," said Langerak. "With the additional load, the Lochinvar boilers have easily kept up."

The administration building has seen a 13% decrease in fuel consumption since last year. The aquatic center has seen a 23% decrease in fuel consumption since last year. This equates to an 18% savings between these two buildings strictly from the boiler installations.

"The boilers have performed just as they should," said Langerak. "Our goal was to install an energy-efficient heating system that would be able to accommodate our growing student population and building expansions. The new Lochinvar boilers, operating with advanced control systems, provided the needed heat and cost savings we are striving to achieve."ES