Final summary:
- Hot air oven out of the Box
electrical safety is absolutely noneexistent whole case was not grounded, just one screw 
stinky tape which will smell horible if not removed
sucks for my understanding what I expect from a good product
gets leaded stuff done with enough heat
but can cook or leave stuff unmolten
- new Firmware and cold junction compensation
better, but the real board temperature is way off what is measured from the sensos between the IR tubes
option to calibrate the temperature probes
still measuring air temperature on a IR oven is total wrong aproach
- Probes moved to some dummy boards
while the temperature looked good measuring the air temperature now the truth is measured, pretty disappointing
- hot air circulation fails
now it shows its waekness, 800-900W heating power is not enough not even the claimed 1500W
does not work anywhere close the heating profile when hot air is on
tried to have hot air fan on from beginning, but heat up was slow so turned it off
hot air fan on during soak and peak temperature on, manually heated longer than in profile overriding heat tubes
- IR tubes replaced with 2kW tubes, bigger fan and taped the fans airflow airtight
now its working like expected, air circulation during whole reflow
I can run the hot air fan all the time
