1. On a fall in relative humidity in the return air plenum, the return air transmitter will send an appropriate signal to its controller which will provide an output signal to the signal selector.

2. The discharge air transmitter will supply a signal to its controller with a decreasing signal as the relative humidity in the discharge plenum approaches 85% RH. The discharge air controller will supply an appropriate output signal to the signal selector.

3. The signal selector will select the lowest input signal between the return air and discharge air controllers and will supply this signal to the modulating valve on the Control Section.

4. If the system employs a multi-manifold staged output system, the control logic will provide two or more staged, modulating signals to the Control Sections.

5. An air flow switch will shut down the system automatically if there is no movement of air in the plenum.

6. If so desired, the Herrmidicool system will be interlocked to preclude simultaneous operation of mechanical cooling and evaporative cooling and shall also provide inputs for a freeze stat and a remote on/off switch.