Where should return air grilles not be located?

Return air grilles should not be located in bathrooms primarily due to the potential for high humidity levels commonly found in these areas. Bathrooms often contain sources of moisture, such as showers or baths, which can lead to condensation when air is circulated through ductwork. This moisture can ultimately promote the growth of mold and mildew within the HVAC system and ductwork, adversely affecting indoor air quality and potentially leading to costly repairs and maintenance.

In contrast, placing return air grilles in areas like living rooms, kitchens, and hallways is generally acceptable and can contribute to the overall efficiency and performance of the HVAC system. In these spaces, the return air grilles help ensure that there is balanced airflow throughout the home, efficiently circulating conditioned air, and preventing temperature imbalances.