At a university in northern California, a centralized system that supplied steam to heat exchangers for space and indirect domestic-water heating was operating at only 50- to 60-percent efficiency, largely because the university’s plant had to operate continuously to meet year-round domestic-hot-water demands. The result was high energy bills school administrators knew they had to lower.
Efficient, As-needed System
An outside engineering firm was retained to revamp the system. Clyde Equipment Company Inc. was hired by the project leader, and the two concurred the system needed to be replaced with a much more efficient, as-needed solution.
For the domestic load, two Innovation 1060 tankless water heaters from AERCO International Inc., which have 20:1 turndown, were installed. To handle dormitory heating requirements, two Benchmark 3000 hydronic boilers with 15:1 turndown, also from AERCO International, were designed into the system. Combined, the solutions provide 96-percent efficiency.
In addition to the high turndown, the tight ±4°F temperature control of the Innovation 1060, achieved in part by the unit’s advanced control system, which incorporates dynamic feed-forward sensing, helps to lower the university’s energy bills. Meanwhile, the tankless design of the Innovation units allows the system to operate at setpoints of 120°F or less.
With a wide operating range of 200,000 Btuh to full-fire input capacity of 3 million Btuh, the Benchmark 3000 not only meets the heating demands of the dormitories, it improves operating efficiency by precisely matching the fluctuating loads common in living quarters. At the lowest firing rates, the Benchmark 3000’s heat exchanger becomes greatly oversized in proportion to the load, allowing much greater thermal transfer to take place. The result is lower energy use during part-load operation, which characterizes the majority of the university’s heating season, for improved operating efficiency and seasonal fuel savings.
As with nearly all retrofits, space was a major consideration. The Innovation 1060 and Benchmark 3000 met the university’s needs with their small footprints and low mass. The tankless design of the Innovation 1060 saves space. Measuring only 78 in. high by 28 in. wide by 56 in. deep, the Benchmark 3000 is extremely compact. Both units fit easily through a standard doorway and have a variety of venting options, attributes that helped to make installation in the pre-existing space much easier.
The installation went smoothly, and the new system was fully operational in time for the start of the school year. The Innovation 1060 water heaters and Benchmark 3000 boilers exceeded all expectations. In the first year of the units’ operation, the school saved $48,000 compared with the previous year. At that rate of efficiency, the units will pay for themselves in only three years. Because of the initial project success, the university administration contracted to have two additional dormitories upgraded with three Innovation units.