NEW YORK - Rooftop manufacturers brought big changes to rooftop units this year at the 2008 International Air-Conditioning, Heating, Refrigerating Exposition (AHR Expo).

Highlighting green technology and new branding efforts, they also considered maintenance ease and building footprints when creating their new additions to their rooftop families.


Carrier Corp.( introduced Novation™ heat exchanger technology on its Centurion™ rooftop units. This heat exchanger technology, widely used in the automotive industry, is now standard with a three-year coil warranty on all Centurion rooftop units 18-25 tons. According to the company, this new technology makes its rooftops smaller, lighter, and requiring less refrigerant.

“Using the Novation coil technology allows us to reduce the size of the rooftop by 10 percent and the amount of refrigerant by 57 percent,” said Chris Nelson, vice president and general manager, Commercial Unitary Systems. “It also aids the LEED certification process.”

The technology has reduced braze joints and refrigerant tubing. This helps improve product reliability, said the company.

Johnson Controls’ newly branded rooftop unit made its debut, also featuring the new Light Commercial Control System that is displayed on top.

Johnson Controls Inc.( launched its branding effort, displaying a rooftop unit with the name and logo of Johnson Controls on the side. This 7.5-ton rooftop unit has a standard cabinet and uses R-410A. It offers two-stage heating and two-stage cooling as well as multiple factory-installed options. It can be specified for cooling only, cooling with electric heat, and cooling with gas heat.

The unit is convertible for side or down airflow discharge with single enthalpy economizers used in either application. Each unit comes charged, wired, and pipe tested. It provides for tool-free maintenance with hinged doors for all access panels, a slide-out blower and blower motor tray, and a self-tensioning blower belt.

Along with the unit is the new Light Commercial Control System. This system employs self-discovery and self-configuration, and a color touch screen is user friendly for nontechnical staff. The system supports single-zone units, pressure-dependent VAV systems, and pressure-independent VAV systems.

“We will continue to be a diversified multi-industrial company, dedicated to improving comfort, safety, and sustainability with innovative products and services,” said Stephen Roell, CEO, Johnson Controls. “Each of our businesses plays an enormously important role in making life better and easier in the places where people spend most of their time.”

Carrier’s Novation™ heat exchanger technology is now a standard feature on the company’s Centurion™ rooftop unit line.

Lennox International Inc.( showcased its new Strategos™ rooftop unit, a 2008 AHR Expo Innovation Award winner, concentrating on its easy maintenance and high efficiency.

According to Larry Wei, product manager, Commercial Rooftop Units, Lennox, “There is no better option than Strategos rooftop units for light commercial building owners looking to upgrade to industry-leading efficiency.”

The unit has efficiency ratings up to 14.3 EER, 16.1 SEER, and 16.4 IPLV. It also has new multistage air volume (MSAV™) supply fan technology, which allows the unit to conserve energy during partial cooling operation while meeting comfort requirements, said the company.

With four compressors, the unit provides four stages of cooling. Its Integrated Modular Controller has over 200 codes for system setup and troubleshooting. Other features include an independent motor mount, full-perimeter base rail, a slab coil, a corrosion-resistant cabinet, an isolated compressor compartment, a slide-out blower deck, hinged toolless access panels, and a swing-out economizer air hood.

“Strategos units are up to 66-percent more efficient than the most stringent requirements of the U.S. Department of Energy and ASHRAE,” noted Wei. “That translates into real dollar savings for our customers.”

Available in 3- to 20-ton models, all units are preset from the factory and should assist building owners in obtaining LEED® certification.

Publication Date:02/18/2008