What causes flames with yellow tips?

Flames with yellow tips are typically indicative of insufficient primary air. In gas combustion, proper airflow is essential for achieving complete combustion of the fuel. When there is not enough primary air mixed with the fuel, the combustion can become incomplete, leading to a yellow flame. This yellow coloration is primarily due to the production of soot and unburned fuel particles that are produced when combustion is inefficient.

In a well-balanced combustion process, an adequate mixture of fuel and primary air allows for optimal burning, resulting in a blue flame, which signifies complete combustion. Therefore, the presence of yellow tips on flames serves as a clear indicator that the air-to-fuel ratio needs to be adjusted for better combustion efficiency.