If you are going to wire flexwatt into your rack, each 1 foot section of 11 inch flexwatt requires 20 watts and the Helix DBS1000 has a 500 watt maximum. You could theorhetically run 25 feet of 11 inch flexwatt off one thermostat without the power module you described. However I would not want to max out my expensive thermostat. I would put around 22 feet on one thermostat.
Each 1 foot section of 4 inch flexwatt is 8 watts. You could run somewhere around 60 feet of 4 inch flexwatt on one thermostat.
Each 1 foot section of 3 inch flexwatt is 10 watts (more than the 4 inch). You can run 45-50 feet of 3 inch flexwatt on one thermostat.
Each 1 foot section of 17 inch flexwatt requires 10 watts (less than the 11 inch flexwatt). You can run 45-50 feet of 17 inch flexwatt on one thermostat.
I think these numbers are correct. Someone correct me please if I am wrong as I have never wired up this many feet on one thermostat
Brad Ratliff