Is it true or false that air that is exhausted must not be recirculated?

The assertion that air that is exhausted must not be recirculated is false. In many HVAC systems, especially within mechanical ventilation systems, it is possible to recirculate air under certain conditions. For instance, in systems equipped with appropriate air filtration and purification measures, exhausted air can be treated and then mixed with fresh air before being re-introduced back into the living or working space.

Recirculating air can be efficient in reducing energy costs as it minimizes the amount of conditioning required for fresh air. However, it is essential to ensure that the recirculated air does not contain pollutants or contaminants that could affect indoor air quality. Systems often incorporate filters and sensors to monitor air quality, which allows for the safe recirculation of air when necessary.

In summary, while there are valid reasons and conditions under which air should not be recirculated, stating that it must never be recirculated does not reflect the practices used in many HVAC systems today.