When a natural gas furnace has flames that are more yellow than blue, what corrective action should be taken?

When a natural gas furnace exhibits flames that are more yellow than blue, it typically indicates that the gas combustion process is not receiving enough air to burn efficiently. A yellow flame suggests incomplete combustion, which can lead to the production of carbon monoxide and other harmful byproducts.

Opening the primary air ports allows for an increase in the amount of air mixed with the gas. This ensures that the combustion process becomes more complete, resulting in a more blue flame, which signifies that the furnace is burning fuel more efficiently and safely. Adjusting the air intake helps achieve the correct air-to-fuel ratio necessary for optimal combustion.

The other corrective actions do not directly address the immediate issue of flame color due to insufficient air supply. Replacing the burner assembly might not be necessary if the issue can be resolved by adjusting the air intake. Increasing gas pressure could exacerbate the incomplete combustion, leading to more yellow flames. Cleaning the blower fan is crucial for overall system efficiency but does not directly impact the combustion air supply or flame characteristics.