When might an LP gas furnace exhibit yellow flames instead of blue?

An LP gas furnace exhibiting yellow flames instead of blue typically indicates an improper air-to-gas ratio. In a properly functioning LP gas furnace, the flame should be a crisp blue, which signifies complete combustion of the gas due to the right mixture of fuel and air. When there is insufficient air in the mix, or too much gas relative to the air, it causes incomplete combustion. This incomplete combustion results in the formation of carbon particles, which glow yellow when heated, leading to the appearance of yellow flames. This is not only a sign of inefficiency but also a potential safety hazard, as it may indicate an increase in carbon monoxide production. The appearance of yellow flames serves as a visual cue that maintenance or adjustment is needed to correct the air-to-gas ratio and restore proper combustion within the furnace.