Every heat source should have its own thermostat channel. Let's say you have a divided enclosure. You have 1 strip of flexwatt and 2 RHPs with the same wattage. Could you run both the RHPs on one channel? Sure, you just have to make sure you're monitoring temps in case things go wrong. The better thing is to make sure each heat source has its own thermostat channel. 3 heat sources means 3 thermostat channels. You can either run each one on its own thermostat, or you can buy one unit to run them all, like a Herpstat 4.