AAON RZ Series Rooftop Units are designed to be selectable with all the features needed for a job, making it a simple, turnkey piece of equipment designed to minimize installation time and reduce labor costs.
It was these features, and more, that led the contest's panel of engineering judges to select the RZ Series Rooftop Units as the 2021 Commercial Comfort Product of the Year in the Rooftop category.
The units, available from 45-261 ton with air-cooled or evaporative condensers, feature variable-speed compressors that operate together to maintain an even, full-face cooling capacity across the evaporator coil. This allows for precise and efficient control of the supply air conditions.
The RZ Series rooftop unit offers up to 4,500 MBH of gas heat, with 50:1 modulating turndown on the largest size, and a 25-year warranty on the heat exchanger.
RZ Series Rooftop Units are highly customizable and can be adapted to provide a solution to nearly any application.
“It can be selected as an air-cooled DX; evaporative condensed DX; a water-source heat pump; or a hydronic air handling unit with gas, electric, hot water, and steam heating options,” said Eric Taylor, marketing manager, AAON Inc. “Economizer and energy recovery wheel options are available to enhance IAQ along with high-efficiency and HEPA filters, UV lights, bipolar ionization, humidity control, and airflow monitoring.”
Variable-speed compressors, variable-speed supply fans, variable-speed head pressure control, and modulating heating options allow for variable air volume control. AAON’s modulating hot gas reheat control, modulating cooling and heating capacity control, and the unit’s ability to handle 100% outside air allow for dedicated outdoor air system (DOAS) applications.
Research & Development
The product was in research and development for more than five years before hitting the market. Computational fluid dynamics (CFD) analysis was key in designing the air-cooled condenser coil banks for ideal airflow, and state-of-the-art computer simulations and laboratory testing were utilized to design motor mount frames with minimal vibration and sound. New damper and fan design prototypes were 3D printed in-house to optimize component design and performance.
“AAON has the only lab chamber in the world that can measure capacity and sound simultaneously at large tonnages,” Taylor said. “The NAIC [Norman Asbjornson Innovation Center] sound and psychrometric chamber has an indoor cooling capacity of 300 ton that can test full- and part-load capacities, airflow, sound, efficiency, vibration, cabinet leakage, and controls integration.
“Additionally, component performance testing in the AAON NAIC laboratory helps to determine the best parts to go into AAON equipment and the best way to optimize and control them,” Taylor continued. “This allowed AAON to design down to 11% turndown using two or four variable-speed compressors that run together to keep the full-face area of the evaporator evenly controlled.”
Almost every aspect of the RZ Series Rooftop Units can be optimized for the specific needs of the project. There are several different coil size options for each tonnage; draw through or blow through supply fans; openings for the supply and return can be either top, bottom, left, or right; up to 12 supply fans and redundancy is available; filters can be pleated, cartridge, or bag; gas heat, electric heat, hot water coil, steam coil, and energy recovery wheel options exist; and several maintenance accessories are also available. Finally, additional option boxes can be selected to add space for field installed items.
The Votes Are In
One judge was impressed how the unit achieves such high levels of energy efficiency through multiple technologies.
“The unit is extremely efficient from all possible perspectives, plus the evaporative condenser will improve the efficiency in appropriate climates,” she said. “This unit could be a best fit for large facilities, such as pharmaceutical plants or hospitals, enhanced by its semi-customized ‘turnkey’ design.”
For another judge, it was the breadth of customization that pushed the RZ Series into the winner’s circle.
“With air-cooled DX, evaporative condensed DX, water-source heat pump, and hydronic options available on the cooling side — in addition to gas, electric, hot water, and steam heating options — it is hard to think of an application where this unit couldn’t be a potential solution,” he said. “Additional options, such as a fully modulating economizer and energy recovery wheel, offer improvements to efficiency, while HEPA filters, UV lights, bipolar ionization, humidity control, and airflow monitoring are available to manage IAQ.”
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