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Gold medal. Model L Rooftop Units.
Model L Rooftop Units

The Gold award in the HVAC Light Commercial Equipment category goes to the Lennox Model L™ Ultra-High Efficiency Rooftop Unit. The 3- to 25-ton Model L ultra-high-efficiency rooftop units offer ratings up to 22.5 SEER, 23.3 IEER, and 15EER and were designed to deliver the lowest total cost of ownership through variable-speed technology and intelligent operation.

“The Model L rooftops feature the revolutionary Lennox CORE unit controller and advanced variable-speed technology to maximize energy savings,” said Eddie Chavez, director of commercial product management at Lennox. “But that’s just the beginning. Premium diagnostic features reduce installation, service, and maintenance expenses to provide the lowest total cost of ownership in the industry.”

The Model L rooftop units and the Lennox CORE Control System utilize optional wireless sensors, a mobile service app, and a built-in wireless gateway to help deliver the lowest cost of ownership. The Lennox CORE Service App replaces a traditional built-in user interface on the CORE unit controller and provides guided setup menus for install, test and balance, and network integration. The app also facilitates seamless commissioning of wireless sensors and sensor networks compatible with the CORE Control System.

Each Model L unit comes with four thermistors per stage that allow the CORE unit controller to make smart decisions and relay relevant information to technicians, which will allow them to get on and off the roof more quickly while providing the correct service. The diagnostic and sensor system allows for the CORE controller to communicate superheat and subcooling without having to hook up gauges to the unit’s refrigeration system.

Johnny Leach, president of Central Lighting and Energy LLC in Boerne, Texas, has been installing Lennox rooftops for over 10 years, but he noted that the new Model L controller with Bluetooth is exceptional. He said that programming and servicing the units is so much easier than previous versions, as he and his crew can simply set up the appropriate parameters and download them to all units in a matter of minutes.

“Typically, we install 16 to 24 units per job, and in the past, it would take us about 20 minutes per unit to program,” he said. “This programming time has been reduced to around two to three minutes per unit, which saves hours of programming on each project. Obviously, this shows up on the bottom line of our projects.”

Chavez noted that each Model L unit comes standard with BACnet IP, as well as MS/TP and premium options such as Humiditrol, a new modulating dehumidification system. Standard toolless filter access, isolated compressor compartment, and an accessible gas compartment reduce service time.

“Each of these features allow technicians to quickly perform service and maintenance on every Model L rooftop unit,” he said.

Designing the Model L product line took more than three years of research, development, and execution. The first phase consisted of upfront technology evaluation to find the optimal efficiency versus cost point while maintaining a cohesive, service-friendly product line. The next phase was spent finalizing specifications and design for the features and functionality of the unit controller, mobile service app, and unit itself to provide the best possible commissioning and service experience product.

“We also held focus groups throughout development with HVAC technicians from some of our National Account customers and contractors to gather a diverse voice of customer needs,” said Chavez. “We conducted jobsite surveys and shadowed technicians as they installed and commissioned our equipment to see what they spend the most time on and how we could improve the process.”

Chavez added that early research and years of development have led to an overwhelming positive response from National Accounts and the engineering community.

WeatherExpert Variable-Speed Series.
WeatherExpert Variable-Speed Series with EcoBlue Technology

The Silver award in the HVAC Light Commercial Equipment category goes to the WeatherExpert® Variable Speed Series – with EcoBlue™ Technology by Carrier. These compact, ultra-high efficiency, single packaged RTUs are cost effective and provide a low cost of ownership and reliable comfort heating, cooling, and ventilation for a wide range of building applications.

This new single-package rooftop design includes all the cooling, heating, ventilation, and IAQ needs from one device for zone comfort control. Fresh air with CO2 control and free cooling is provided through the unit’s internal economizer design and can be integrated with Demand Control Ventilation and Fault Detection and Diagnostic controls. The unit footprint is the actual same size as those from the late 1980s to ensure that replacement opportunities do not require expensive adapter curbs or a total roof curb replacement.

The RTUs were designed over the course of three years through a partnership between an internal Carrier cross-functional team of engineers, manufacturing, quality, sales, controls, and applications experts and customers including contractors, installers, engineers, and controls and service companies. Carrier also utilized its modeling capabilities to help testing and design processes, and 3-D printing for prototypes for product reviews.

Carrier plans to further expand the WeatherExpert RTU offering and get ready for the new DOE efficiency levels in 2023 along with supporting the phasedown of HFC refrigerants.

LS25 Separated Combustion Unit Heaters.
LS25 Separated Combustion Unit Heaters

The Bronze award in the HVAC Light Commercial Equipment category goes to the LS25 Separated Combustion Unit Heaters by Lennox. These separated combustion unit heaters are designed to provide heating in applications where it is necessary to use outside air for combustion to protect the heating system or to avoid negative pressure within the building. Applications include greenhouses, automotive repair shops, garages, and manufacturing facilities.

The LS25 comes with factory-installed seals that improve the integrity and reliability of the product for every installation and allow for a quicker, cleaner install for the contractor. Removeable terminal blocks for both line voltage and thermostat wires allow technicians to remove the plugs from the board, quickly wire the connections, and re-attach the plug, which saves times and prevents the installer from having to reach inside the unit to wire up to each terminal.

As part of the two-year design process for the unit heaters, Lennox interviewed its sales team to understand the needs of the market, as well as what specific items installers struggle with on the company’s older TUA models. Feedback was also gathered from Lennox national

account service technicians who install the equipment on a regular basis.

In the future, Lennox plans to expand the heating sizes of the separated combustion unit heaters down to 30 kBtuh so that it can be used in both residential and commercial applications.