What happens when there is an insufficient flow of secondary air?

When there is an insufficient flow of secondary air, a yellow flame may develop. In combustion systems, the proper mixing of fuel and air is crucial for achieving an optimal flame condition. Secondary air is responsible for providing additional oxygen for the complete combustion of the fuel. Without enough secondary air, the combustion process becomes incomplete, leading to the production of soot and other unburned fuel particles, which manifest as a yellow flame.

A yellow flame indicates that the combustion is not efficient, which often suggests that there is a problem in the air-fuel mixture. In contrast, a blue flame indicates proper combustion with adequate air. The presence of a yellow flame is not only a sign of inefficiency but also indicates potential safety hazards, as incomplete combustion can produce hazardous by-products, such as carbon monoxide.

Therefore, recognizing a yellow flame is critical for operators and maintenance personnel to ensure the appliance is functioning correctly and safely.