Ducts operating at temperatures above what limit need sufficient thermal insulation to limit surface temperature?

When evaluating the need for thermal insulation on ducts, it's important to consider the temperature at which the surface of the duct can become a safety hazard or lead to energy loss through conduction. Ducts operating above 120°F typically require sufficient thermal insulation to ensure that their surface temperature does not exceed safe limits. Insulating ducts at this temperature helps to prevent heat loss, improves system efficiency, and minimizes the risk of burns or heat-related damage to surrounding materials or individuals.

In HVAC systems, excess heat escaping from high-temperature ducts can diminish the system's overall efficiency and increase energy costs. Therefore, maintaining a surface temperature below this threshold through proper insulation is key to both safety and operational effectiveness.