Humidity often needs to be added to the conditioned air in the __________ mode.

Humidity often needs to be added to the conditioned air in the heating mode because heating air without adding moisture can lead to excessively dry indoor environments. When the air is heated, its capacity to hold moisture increases, which can result in lower relative humidity levels in the space.

In situations where the air is heated, such as during winter months, there is a greater likelihood of the air feeling dry, causing discomfort and potential health issues like dry skin or respiratory problems. Therefore, it is beneficial to introduce humidity to maintain a comfortable and healthy indoor environment.

In contrast, during cooling or dehumidifying modes, the goal is often to remove moisture from the air, whereas in ventilating mode, air exchange with the outdoors does not inherently involve adding humidity. Thus, the need for adding humidity is most pertinent during the heating mode.