David,

I'd be interested in replies also. From experience heating and bending Schedule 40 PVC conduit up to 5" (with a 0.188" wall) it takes a constant and consistent heat. For the big stuff we use an electric blanket of sorts. Could possibly use an electric space heater? The real trick would be NOT burning one side to get the 1/2" thickness soft enough to bend. Maybe two heaters (with fans) set close together heating both inside and out at once?