ATLANTIC CITY, NJ — At the International Air-Conditioning, Heating, Refrigerating Exposition (AHR Expo), Lennox Industries Inc. (Carrollton, TX) announced some significant new enhancements to its L Series® line of commercial packaged rooftop units, including improvements in efficiency and dehumidification.

According to the company, the L Series was designed to lower energy bills, reduce the cost of installation, and minimize maintenance costs. The result is a line of heating and cooling systems with some of the latest technological advances and one of the lowest lifecycle costs in the industry, available in 3 to 30 tons gas/electric, electric/electric only, and heat pump models.

Through the L Connection Network, the Network Control Panel (NCP) interconnects up to 31 members of the network.


Improvements to the L Series rooftop units include higher efficiencies on its standard efficiency models to comply with ASHRAE Standard 90.1-1999, “Energy Standard for Buildings Except Low-Rise Residential Buildings.” The L Series rooftop unit has some of the highest energy-efficiency ratings (12.0 EER and 13.4 IPLV) in the industry to reduce energy costs.

The Humiditrol® dehumidification system, offered as a factory-installed option, is now available on the 13-, 15-, 17.5-, 20-, and 25-ton models. Previously, the option was only available in the 3- to 12.5-ton rooftop units.

“Humiditrol removes 800% more moisture than the leading competitor’s product and increases indoor air quality by providing dehumidification on demand without overcooling the room,” said John Whinery, director, commercial marketing.

“In addition, this is the only product that can stage its multiple compressor circuits to optimize its energy use for humidity control. With the Humiditrol option, Lennox provides the design engineer a better product solution for controlling humidity levels in the room, while still meeting the ASHRAE 62-1999 fresh air guidelines.”

The Humiditrol option reduces the potential for mold and bacteria growth by lowering humidity levels in the room. It operates conventionally as an air conditioner when there is a demand for cooling. If the thermostat is satisfied, but humidity levels are too high, a dehumidification cycle is initiated. Using the evaporator to cool and dehumidify the air, and a hot-gas condenser reheat coil to minimize the sensible cooling of the evaporator, the unit is able to reduce humidity levels without overcooling. The unit shuts off when both the temperature and humidity levels in the room are at their desired set points.

The Lennox L Series rooftop unit has some of the highest energy-efficiency ratings in the industry.


Installing the L Series units is said to be efficient and cost-effective with factory-installed and

-tested options and fully insulated bases. Access doors requiring no tools, color-coded and numbered wiring, and temperature sensors are standard features, simplifying L Series unit maintenance. Fourteen cooling capacities ranging from 3 to 30 tons are available in five different footprints to reduce the number of roof and adapter curbs.

“It’s easy to walk up to the L Series rooftop unit, turn the handle to open the door, and change the filter,” said Whinery. “Other manufacturers’ rooftop units require unscrewing panels to get into the unit.”

The Integrated Modular Control (IMC) system, another standard feature, is a combination rooftop controller and direct digital controller that has a built-in test mode designed to make start-up simple. Extensive diagnostics help identify the location of any problem with easy-to-read diagnostic codes, instead of blinking lights.

“The IMC is a smart, cost-effective way to control the unit’s performance so customers and employees are kept comfortable and rooftop units operate efficiently,” said Whinery.


Several sister products to the IMC enhance its capabilities, providing a sophisticated light commercial control. These include:
  • Network Control Panel (NCP) — The NCP connects up to 31 members of the L Connection Network. It features time-of-day scheduling, zone temperature and humidity control, and date-and-time-stamped IMC alarm codes.
  • Building Controller — This device allows you to make the building a member of the L Connection Network. With this product, you can control multiple building functions such as parking lights, lawn sprinkler systems, signs, and vent hoods.
  • Network Thermostat Control — This control ties non-L Series units, such as the 16 Series, split systems, or even other brand-name units to the L Connection Network.
  • User Interface Software Pack-ages — The software packages are Windows-based PC programs that serve as an interface between the user and one of the L Connection Network hardware devices.
  • LN-1 Notifact™ Transmitter — The LN-1 allows you to monitor the operation of your rooftop units no matter where you are. This wireless communicator transmits the IMC diagnostic codes via cell phone, fax, e-mail, or pager. One LN-1 transmitter can connect up to 10 L Series rooftop units.
“The NCP and the software allow contractors to access and troubleshoot the hvac system off-site,” said Whinery. “This not only saves time, it also saves money. The remote-access capability turns a potential 90-minute service call into a 30-minute service call.”

Publication date: 02/18/2002