I'm assuming a wafer thermostat is what is in the Hovabator 1602- flat metal disks. They are threaded to the end of a metal post that sticks up through the styrofoam. To adjust warmer I turn it so that the disks get closer to the top of the incubator. To adjust cooler I turn it so that the disks move towards the bottom of the incubator. Why? How does this make it warmer or cooler?