I dont know if I am the only one with this problem, but I have both types of the RBI racks and I have a johnsons thermostat. When I put the thermostat on the MCS rack I kept the temp in the rack on the hot spot around 90 degrees. I now have two tubs that have holes in the bottom of them. So we replaced the heat tape and tried again and the same thing happen. With the sweater box rack I have a temp difference of 8 degrees between the top and the bottom tubs on the rack.