What is necessary for equipment and devices to be allowed in ducts or plenum chambers?

For equipment and devices to be permitted in ducts or plenum chambers, the requirement that they must have direct action on the contained air is essential. This principle is rooted in safety and functionality, ensuring that any devices or equipment placed in those areas effectively interact with the airflow. Plenum spaces, which facilitate the movement of air for heating, ventilation, and air conditioning (HVAC) systems, require that any equipment included in these spaces directly affects the air being circulated. This interaction can involve heating, cooling, or ventilating the air as it travels through these areas.

Equipment that does not engage with the airflow in a meaningful way may not belong in plenum spaces, as it could pose risks or impact the efficiency of the HVAC system. By ensuring that devices in these areas have a direct action on contained air, the integrity and safety of the plenum space’s operation are maintained, preventing potential hazards associated with improper equipment installation.