What are typical flue gas temperatures of a category 3 gas furnace?

Typical flue gas temperatures for a Category 3 gas furnace generally range from 300°F to 400°F (about 150°C to 200°C). These furnaces are designed to operate with a positive vent pressure and typically vent through a stainless steel or other corrosion-resistant material. The elevated temperatures are a result of the combustion process and the efficient design of the furnace, which allows for condensing flue gases. Proper venting is crucial to ensure safety and efficiency.