I checked the amount of air discharged from the conveyor and appears to be similar to the previous version. Unfortunately I do not know how to calculate the return pressure but from experiments made using a lighter and smoke, the air leaving the flame goes out immediately already at 7-8 cm of distance. The return pressure is probably only for the top of the fan but I don't think that creates problems. Unfortunately I did not find other solutions to prevent the conveyor touches the top of the printer cover when the Z axis is more than 10 cm in height .. If you have a new Idea to position the FAN I can implements my project.