Forced air heating is a type of space heating that uses fans and ducts to circulate warm air throughout a building. In homes, forced air heating systems typically consist of an outdoor compressor unit, indoor fan coils, and vents. Here's how it works: hot air from the compressor unit is drawn into the indoor fan coil through ductwork, where it warms the surrounding air. The warmed air is then blown into the home via vents, where it can be distributed throughout the space. However, forced air heating performance can be affected by humidity levels in the air. High humidity reduces the effectiveness of forced air heating by increasing the amount of moisture that needs to be removed from the warm air before it can be felt comfortable. This is because our bodies release heat through evaporation, making us feel cooler than we actually are when surrounded by high humidity. As a result, forced air heating systems may need to work harder to achieve the same level of comfort in humid environments. Conversely, low humidity allows the warmed air to dry more quickly, making it feel warmer and more comfortable. This is why many forced air heating systems come with built-in humidistats that can adjust the system's performance based on humidity levels.