Disclosed are apparatus and methodology for controlling humidity (i.e., moisture) within and/or adjacent a coverlet associated with a multi-layer air mattress. Humidity sensors may be incorporated at selected locations within the coverlet and coupled to a controller that is configured to provide a closed-loop control signal to vary air flow rate through the coverlet to control the rate of moisture adjustment, such as removal. In part, present subject matter may include a combination of a Low-Air-Loss (LAL) topper, having a pair of humidity sensors, one of which is at an inlet to the LAL topper and the other of which is at a selected one of existing outlets of the LAL topper. Air flow through the LAL topper is kept constant, in accordance with its basic operation, while the two humidity sensors are part of a closed-loop feedback control system, which adjusts the humidity of the air being input at the inlet. Additionally portions of a closed-loop feedback control system may depend on the sensed rate of change of moisture, to facilitate more rapid response to changing moisture conditions. Separately, and not as part of the control feedback loop, a temperature sensor may be provided for simply indicating the temperature of the air relative to the LAL topper.
