What is a primary cause of lifting flames?

Lifting flames are primarily caused by overrating, which occurs when a burner is operated at a higher input than it is designed for, leading to an excessive fuel-to-air ratio. This condition results in flames that do not adhere to the appliance's burner surface and can create a lifting effect, where the flames appear to be detached or rising above the burner.

Inadequate ventilation, high humidity, and incorrect fuel type can affect combustion efficiency and flame behavior, but they do not lead directly to the phenomenon of lifting flames in the same manner as overrating does. Overrating essentially disrupts the intended balance of fuel and air, which is critical to achieving stable and properly contained flames.