What is UL 673?

UL 673, also known as "Underwriters Laboratories Standard 673," is a technical standard that outlines the requirements for air distribution testing and evaluation in heating, ventilation, and air conditioning (HVAC) systems. This standard ensures that HVAC equipment complies with specific performance criteria related to air leakage and thermal properties. In this article, we will explore UL 673 in detail, discussing its significance, key requirements, and the testing process.

Significance of UL 673

The purpose of UL 673 is to establish a uniform evaluation method for HVAC air distribution products. It ensures that these products meet the necessary performance standards and are safe for use. By complying with UL 673, manufacturers demonstrate their commitment to delivering high-quality products that provide efficient air distribution, minimize energy loss, and enhance indoor air quality.

Key Requirements of UL 673

UL 673 specifies several important requirements that HVAC products must meet to be considered compliant. These requirements include:

Air leakage rating: The standard sets limits for air leakage in different components such as ducts, grilles, and registers. Products should undergo testing to determine their air leakage rate, expressed in cubic feet per minute per square foot of surface area (CFM/sq.ft).

Thermal conductivity: UL 673 provides guidelines for the thermal insulation used in HVAC systems. It specifies the maximum thermal conductivity allowed for insulation material, ensuring energy efficiency and preventing heat transfer.

Fire resistance: The standard establishes fire resistance classifications for various HVAC components, such as ducts and dampers. Products need to undergo tests to evaluate their fire resistance properties and prevent the spread of fire.

Testing Process for UL 673 Compliance

Before HVAC products can be UL 673 certified, they must undergo rigorous testing by qualified laboratories. The testing process involves various assessments, including:

Air leakage testing: Products are subjected to controlled air pressure and airflow measurements to determine their leakage rate.

Thermal conductivity testing: Insulation materials are tested to measure their ability to resist heat transfer.

Fire resistance testing: HVAC components are exposed to flame or extreme temperatures to assess their fire resistance capabilities.

Products that meet all the requirements outlined in the UL 673 standard receive a certification mark indicating their compliance.

In conclusion, UL 673 plays a crucial role in ensuring the quality and safety of HVAC air distribution products. By following this standard, manufacturers can deliver efficient, reliable, and compliant systems to consumers. Compliance with UL 673 not only benefits the HVAC industry but also contributes to energy conservation and improved indoor air quality in buildings.