Which type of heating system uses a network of ducts to distribute warm air?

Forced air heating systems utilize a network of ducts to distribute warm air throughout a building. In this system, air is heated in a furnace and then distributed via a series of ducts and vents. This method allows for effective and efficient heating of multiple rooms or areas, as the warm air can be directed where needed. The forced air aspect refers to the fans in the system that push the heated air through the ducts, ensuring a consistent and controlled temperature throughout the space.

In contrast, radiant heating systems work by emitting heat directly from a heated surface, such as floors or walls, without the need for air distribution. Geothermal heat pumps utilize the earth's constant temperature to heat or cool a building, and while they can also be paired with duct systems for air distribution, their primary function differs from that of a forced air heating system. Hydronic heating systems rely on water movement through pipes to heat spaces, again lacking a duct network for warm air distribution. Thus, the characteristic reliance on ducts for air circulation clearly identifies forced air heating systems as the correct answer.