What does the term "two-stage" in a gas furnace refer to?

The term "two-stage" in a gas furnace specifically refers to the furnace's ability to operate at two different levels of output. This dual-output capability contributes significantly to efficiency and comfort in home heating. In the lower stage, the furnace operates at a reduced capacity to maintain the desired temperature during milder weather conditions, providing a consistent and comfortable environment while using less energy. When temperatures plummet, the furnace can switch to the higher stage to meet the increased heating demand.

This feature not only allows for better energy efficiency but also minimizes temperature fluctuations, resulting in more stable indoor comfort. Utilizing this two-stage operation means homeowners may experience lower energy bills and improved overall satisfaction with their heating system. The other options do not accurately represent the capabilities described by the "two-stage" designation.