![]() | |||||
0811 High Efficiency Furnaces and Duct Sizes - Heating - Condensing Furnaces - Image Text: Conventional gas furnace > 70 degrees Fahrenheit > air flow > heat exchanger > exhaust gases > 140 degrees Fahrenheit to 170 degrees Fahrenheit > air flow > supply plenum > High efficiency gas furnace > take temperature reading here (beyond Standards) > 70 degrees Fahrenheit > air flow > heat exchanger > heat exchanger is designed for 40 degrees Fahrenheit to 70 degrees Fahrenheit temperature rise > small and/or inefficient ducting can reduce airflow over the heat exchanger - causing overheating and stressing the thin-walled exchanger > exhaust vent > 110 degrees Fahrenheit to 140 degrees Fahrenheit > air flow > supply plenum > take temperature reading here |