The probe showed there is 10°C - 30°C difference between the upper and lower parts of the retort.
The thermocouple LCD's were re-housed in a cabinet recycled from an old PC chassis.
Preheating of the feedstock was by 230v recycled water-heater which was targeting 100°C. Several feedstock pumping speeds were tested. These were obtained by changing the motor pulley sizing.
Boil-over episodes continue to frustrate the distillation process so yet another rethink is underway to solve this issue. The feedstock appears to be a factor causing the boil over and this why the yield was down to 150 liters produced.
One remarkable thing realized was that ambient temperature has a significant effect on the amount of heat that needs to be applied. Midwinter with the chill factor after dark really showed this phenomena up.