What does Category I consist of?

Category I consists of appliances that operate with a positive vent pressure and utilize a draft hood for the safe evacuation of combustion gases. These appliances are typically designed to vent directly to the outdoors, relying on natural draft to facilitate proper airflow. The draft hood is crucial as it helps prevent backdrafts and ensures that combustion gases do not escape into the living space, thereby providing a level of safety for users.

High-efficiency appliances belong to a different category, often designed to operate without drafting requirements that necessitate a draft hood. Combination appliances and vent-free appliances also have their own classifications based on their unique properties and venting methods, deviating from the standard characteristics associated with Category I. Understanding the details and specifications associated with each category is essential for ensuring compliance with installation standards and safety protocols in HVAC applications.