NATE Gas Heating Practice Exam

High-efficiency furnaces operate with flue gas temperatures between which ranges?

1. 275 and 360 degrees

2. 200 and 500 degrees

3. 100 and 275 degrees

4. 80 and 100 degrees

The correct answer is: 100 and 275 degrees

High-efficiency furnaces are designed to maximize energy utilization by capturing more heat from the combustion process. They typically operate with flue gas temperatures in the range of 100 to 275 degrees Fahrenheit. This lower range is achievable due to the use of condensing technology, which allows the furnace to extract heat from the exhaust gases effectively. The condensing process captures latent heat by cooling the flue gases to the point where water vapor condenses, thus converting more thermal energy into usable heat for the home. Operating within this temperature range not only improves the efficiency of the furnace, resulting in lower energy costs, but also minimizes heat loss compared to traditional furnaces that may release hot gases at much higher temperatures. By functioning effectively at these lower temperatures, high-efficiency furnaces promote better heat recovery and contribute to overall energy savings and environmental benefits.