What type of warm-air furnaces utilizes a fan for air distribution?

Forced warm-air furnaces are specifically designed to use a fan or blower to distribute heated air throughout a space. This method of air distribution is efficient because it allows for better control over temperature and improved circulation of warm air, making it more effective in heating larger areas quickly compared to other types of furnaces.

In contrast, gravity warm-air furnaces rely on the natural rise of warm air without mechanical assistance, which can lead to less efficient air distribution. Natural warm-air furnaces typically refer to types that function passively and do not utilize a fan system, making them less effective in areas with varying temperature needs. Electric warm-air furnaces may produce heat through electric coils, but they can still fall under different distribution methods that do not necessarily involve forced air circulation. Therefore, the defining feature of forced warm-air furnaces is their integration of fans for enhanced air distribution, distinguishing them from other furnace types.