What category is assigned to an appliance that has positive vent pressure and experiences condensation?

An appliance that has positive vent pressure and experiences condensation falls into Category 4. This classification is used specifically for appliances that vent products of combustion with a positive pressure and typically use sealed venting systems, which can be either direct vent or sealed combustion.

In this category, the venting system is designed to handle the condensation that occurs as a result of the combustion process. This is significant because the positive pressure helps to effectively expel any condensation out of the system, enhancing the efficiency and safety of the appliance.

Other categories differ in their pressure characteristics and handling of condensate. For example, Category 2 and Category 3 appliances operate under different vent pressures and do not necessarily accommodate condensation in the same way, while Category 5 appliances are typically designed for special conditions that are not related to positive pressure and condensation handling. Understanding these distinctions helps ensure that the appropriate venting methods and materials are employed for different types of appliances, ultimately promoting safety and efficiency.