What is the typical flue gas temperature at the exit of an older warm air furnace?

The typical flue gas temperature at the exit of an older warm air furnace generally measures around 230°C (450°F). This temperature is considered standard for older models due to their design and operational efficiencies.

Older warm air furnaces often don't operate at the same efficiency levels as modern units, which means they tend to have higher flue gas temperatures as a result of more heat being lost through the exhaust. The temperature of 230°C indicates that while some heat is transferred to the air being circulated inside the building, a significant amount is also vented out.

In comparison, lower temperatures (like 150°C or 200°C) would typically be associated with more efficient, modern heating systems, while values like 250°C may suggest issues with the combustion process or insufficient heat transfer, making them less common for standard operation. Understanding these temperature ranges helps identify operational characteristics and performance standards of heating systems.