What is the primary benefit of using enthalpy control in humidification?

• A. It favors air streams with lower enthalpy, even if they are warmer.
• B. It increases the total moisture added.
• C. It stabilizes outdoor air temperature.
• D. It reduces energy use.

Answer: (B)

Enthalpy control uses the air’s energy content, which combines its temperature and moisture, as the signal for humidification. When the air’s enthalpy is below the setpoint, moisture is added to raise that enthalpy toward the target. Because enthalpy reflects both heat and moisture, this approach often allows more moisture to be added to reach the desired humidity condition, especially when outdoor air is dry or when the space needs more latent heat to achieve comfort. That focus on achieving the target enthalpy tends to increase the total moisture introduced compared with controls that rely only on temperature or relative humidity.

Other methods that aim to limit moisture or keep temperature steady don’t inherently push more moisture into the air; they’re more about preventing over-humidification or energy swings, whereas enthalpy control directly drives the system to deliver the necessary moisture content to reach the enthalpy target.