What indicates that a gas-fired burner is burning fuel correctly?

A gas-fired burner that is burning fuel correctly should ideally produce a flame that is characterized by a blue color with yellow tips, indicating proper combustion. A long bright yellow flame suggests incomplete combustion, which can lead to unsafe conditions, such as the production of carbon monoxide and the potential for soot buildup.

The presence of minimal flame turbulence is typically an indication of efficient combustion and stable operation. A well-burning gas flame would not exhibit excessive turbulence, as this can also lead to inefficiencies in burning.

Complete darkness around the flame could suggest that the burner is not producing enough light or heat, which might indicate inadequate combustion too.

Finally, visible pulsation of the furnace is often a sign of operational instability, which may indicate that the burner is not functioning properly.

Thus, the presence of a long bright yellow flame does not indicate correct combustion but rather suggests issues that could ultimately harm efficiency and safety in a gas-fired burner system.