What is the typical vent stack temperature on a natural draft furnace?

The typical vent stack temperature on a natural draft furnace is generally within the range of 450°F to 550°F. This temperature range indicates that the combustion gases produced by the furnace are adequately vented to the outside, ensuring efficient operation and preventing back draft or overheating of system components.

Natural draft systems rely on the principles of buoyancy and temperature differences to create the necessary airflow for the combustion process. As the exhaust gases exit the heat exchanger, they carry heat away, and their temperature reflects the efficiency of the combustion process. A vent stack temperature within this range is crucial, as higher temperatures could indicate improper combustion or exhaust issues, while temperatures that are too low might suggest insufficient combustion or heat transfer.

Understanding this temperature range is essential for technicians and HVAC professionals, as it relates to safe and effective furnace operation, and awareness of proper maintenance and inspections can help avoid system failures or safety hazards.