I split the fan & heat circuits too, but I have a router speed control for managing heat. Roasting is more or less a dialed-in process now; preheat with full power, then flip to variable power.
How many amps is your router speed control? I want to split the fan and heater circuits on my TO if I can figure out how to do it. Maybe I'll add the router speed control while I'm at it.
when I opened my TO it was pretty clear what wires went to the fan and what wires to the temp controller/heat elements.. I just wired the fan wires to a new cord now the fan is on if the plug is plugged in.. the heat can be controlled with the built in dial or by lifting the handle on the TO with no effect on the fan..
is the router controller more accurate than the heat control knob that came on the TO from the factory??
The TO's thermostat was the biggest obstacle to using the dial - its dead band was too wide. So when I rewired my TO I did away with the thermostat and wired the element directly to line-in power . I tried using the handle to control heat, but it's either 100% on or 100% off - that's not enough control for someone like me.
With the router speed control you're managing the temp by varying the percentage of power being applied. For example: Say I'm running the TO at 85% to 300, then maybe 90% to 375, then back down to 85% to 1st crack, then ... (These are hypothetical settings, not necessarily the ones I use).
By putting a Kill-A-Watt between the router speed control and the TO, I can measure the wattage applied to achieve a given temperature. Which means I'm now profiling my roasts so I can get some degree of repeatability for future roasts.
It also means I don't have to babysit my roaster as much - I can multitask without having to worry about pooching a roast.