What does the term 'reheat' refer to in HVAC systems?

• A. The process of removing heat from air to cool a space.
• B. The process of mixing return air with outside air.
• C. The process of adding heat to air to maintain desired temperature.
• D. The process of increasing humidity in air.

Answer: (C)

Reheat means adding heat to air to bring it back up to the desired room temperature after it has been cooled. In many HVAC designs, air is cooled and dehumidified at the central air handler, then, to satisfy zones that need warmth, a reheat device (such as electric coils or hot-water/steam coils) heats that cooled supply air before it enters the space. This lets you dehumidify and control temperature efficiently in the central system while still delivering comfortable temperatures to individual zones without overcooling elsewhere.

This term is not about removing heat, mixing air, or increasing humidity. It specifically refers to the heating step applied to cooled supply air to reach the target setpoint.