Category I appliances run with a flue gas loss of no less than what percentage?

Category I appliances are defined by their ability to vent flue gases through a system that does not require positive pressure in the venting system. For these appliances, it's understood that they typically operate with a minimum flue gas loss of 17%. This percentage is significant because it indicates the efficiency and performance of the appliance.

The flue gas loss refers to the amount of energy from the combustion process that escapes into the atmosphere rather than being converted into usable energy in the system. A flue gas loss of 17% or more demonstrates the threshold where these appliances are categorized, allowing for safe venting practices while ensuring that a certain level of efficiency is not sacrificed. Understanding these parameters is crucial for HVAC professionals as they design, install, and maintain heating systems.