I have an 18 tub 9 shelf rack hooked up to a VE‑200 T-stat. I used an adapter (converts one plug into two) I picked up at Walmart as well as two 6 plug surge protectors. I placed the probe mid on the mid level shelf. The VE-200 handles up to 700 watts. So since each three foot section of 4" flexwatt is about 18 watts I was well under the limit. No issues with higher shelves being hot compared to the lower shelves except maybe by a degree or two.