Where are filter pads located in a forced warm-air unit?

In a forced warm-air unit, filter pads are primarily located inside the duct system. This location is crucial for maintaining good air quality and ensuring the efficiency of the heating system. The filter pads serve to capture dust, allergens, and other particles from the air before it is circulated throughout the living space, preventing these contaminants from entering the home environment.

By placing the filters within the duct system, they can effectively clean the air as it moves through the ducts. This also allows for a more even distribution of filtered air into various rooms, resulting in a healthier indoor environment. Additionally, regularly maintaining and replacing these filter pads is essential for optimal airflow and energy efficiency, as clogged or dirty filters can restrict airflow and lead to system inefficiencies.

The other options do not accurately reflect typical filter pad placement in a forced warm-air system. For instance, while the plenum is part of the heating system, it usually acts as a distribution point rather than containing the filters themselves. Similarly, filters are not located at the bottom of the unit or outside the house, as these locations would not effectively capture contaminants before the air is heated and distributed.