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Your guide to single-zone VAV regulation

As new commercial building codes and regulations continue to shape the HVAC product landscape, customers depend on engineers and contractors to help them keep up with changing requirements and standards.

The newest codes to affect the HVAC industry include ASHRAE 90.1-2010 and California Title 24, which require all constant volume direct expansion cooling units, which serve a single zone and are equal to or greater than 110,000 British thermal units (Btu), to have supply fans controlled by two-speed motors or variable speed drives.

While this new regulation for single-zone systems focuses specifically on saving energy during the cooling mode, several HVAC manufacturers have answered the call with staged air volume systems that can help save energy in more than one operation mode.

Lennox achieves this goal through its patented MSAV® (multi-stage air volume) supply fan technology, created to offer customers year-round comfort and savings while helping systems achieve or even exceed new supply fan requirements. By providing up to 75% supply fan power savings and improving indoor comfort with up to 29% better dehumidification at a reduced airflow operation, this new technology can help customers dramatically reduce energy consumption in HVAC units. Performance is also significantly enhanced with an advanced variable frequency drive.

Additional benefits of Lennox' MSAV supply fan technology include:

  • Quick and easy unit start-up
  • Part-load IEER efficiency improvements up to 27%*, depending on model
  • Code compliance on supply fan requirements for ASHRAE 90.1-2010 and California Title 24
  • Utility rebate eligibility

Lennox' MSAV supply fan is available as a factory-installed option for Energence® 3- to 25-ton models, Strategos® 10- to 20-ton models and Landmark® 7.5- to 25-ton models and as a field-installed option for T-Class™ large split systems.

When installed in Lennox' Energence rooftop units, MSAV technology offers customers energy-saving configurability, with up to seven programmable speeds featuring full adjustment capability and four modes of operational savings that include part-load cooling, heating, ventilation and smoke. A patent-pending VFD automatic bypass option, located in an isolated compressor compartment to protect against moisture, maintains comfort while decreasing potential for downtime. Three outdoor air damper positions optimize air intake, reducing energy costs associated with over-ventilation. Finally, MSAV technology offers customers improved dehumidification performance when combined with Lennox' Humiditrol® dehumidification system for rooftop units.

*At 67% airflow when compared to full load.

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