Which of the following is typically formed in concentric cones or pyramids?

The correct answer is that diffusers are typically formed in concentric cones or pyramids. Diffusers are designed to distribute air evenly throughout a space and are often constructed in these geometric shapes to facilitate optimal air flow and coverage. The design of concentric cones or pyramids allows the diffusers to direct the airflow in a methodical manner, effectively spreading conditioned air across a larger area without creating hot or cold spots.

The construction of these diffusers with layered or tiered shapes helps in managing the velocity and direction of the air, important factors for ensuring comfort in indoor environments. In HVAC systems, effective air distribution is critical to achieving energy efficiency and maintaining desired temperature levels.

Other options such as vents, chimneys, and filters serve different purposes within residential or commercial systems. Vents typically grant access for airflow but are not structured in the same way as diffusers. Chimneys serve the function of venting combustion gases from fireplaces or heating appliances and are generally cylindrical or rectangular rather than conical. Filters are designed to capture particles from the air but do not employ geometric formations like cones or pyramids in their design.