Two-stage heat, one serious commitment to performance. Conventional furnaces are either off or on. But the 2-Stage Variable 90% Furnace can output heat at two different intensities, allowing it to fine-tune your comfort and your energy use in perfect balance, making your air feel great, even in the summer. It also has the power to make your home feel better during summer months. By operating at its lower speed, air spends more time in contact with the outside coil, the cooling engine of your air-conditioning unit. This helps reduce moisture levels inside your home to enhance your comfort.