UL-103HT is a widely recognized standard for factory-built chimneys and venting systems used in residential and low-heat applications. It sets forth the requirements for construction, installation, and performance of these chimneys. Chimneys and components that comply with UL 103 have undergone rigorous testing to ensure they meet the safety and quality standards established by Underwriters Laboratories. The standard covers various aspects such as clearance to combustibles, insulation, materials, and joint integrity. UL 103-certified chimneys provide assurance that they have been manufactured and designed to meet the specific requirements for safe and efficient venting of flue gases. It is important to choose UL 103-compliant products when installing a chimney to ensure compliance with relevant regulations and codes and to ensure the safety of your residential or low-heat application.