I'm surprised this isn't standard on all pellet stoves these days. Having to fiddle around with the damper to get/guess at the right air fuel mixture just can't be efficient. I have a Bosch wide band O2 sensor and a controller which heats it up and does the conversion. It also has a mappable 0 to 5.0 v analog output. I'd like to weld an exhaust bung on the appliance adapter and use the output of the O2 controller into a general purpose pid controller which would in turn control a stepper motor attached to the damper rod. Are there any stoves out there that have closed loop air fuel combustion like cars have had since the previous millenium?