Rack Issues Need Help

How long is the total length of flexwatt? The longer it is, the more of a temperature variance you will have from one end to the other.

Are you using the black flukers digital thermometer? that one is good for measuring ambient air temperature but not surface temperature. Try sticking a probe right on the plastic where the flexwatt is and see if that gives you a more consistent reading.

The shelves will vary in temperature by a couple degrees. The top shelf is usually hotter then the bottom shelf, not the other way around.