What type of AHU does not have a heating coil?

• A. Thermal reheat
• B. VAV AHU
• C. Packaged AHU
• D. Dual-duct AHU

Answer: (A)

Understanding where heating happens in AHU systems helps answer this. In a thermal reheat setup, the air is cooled first and then reheated by a heating coil inside the AHU, so the AHU clearly includes a heating coil. In a packaged AHU, heating and cooling coils are built into the unit as well, so it also has a heating coil. A dual-duct AHU delivers two separate air streams and typically provides heating in the hot duct, either within the AHU or in associated equipment, so it also includes heating capability. A VAV AHU mainly supplies air through a cooling coil, and any temperature control to zones is achieved by reheat in the VAV boxes rather than in the central AHU, so the central AHU often does not carry a heating coil. Because of that, the AHU type that does not have a heating coil is the VAV AHU.