axi 760 psu installation fan grill up or down?

hi i have just got the apevia x-dreamer 4 and the axi 760 psu. the psu mounts at the bottom of the case it also has a fan grill at the bottom of the case. Now i want to know what is the recommend way to mount the psu at the bottom of the case,. does the psu mount fan grill down where the air is drawn from the bottom of the case into the psu then out the back, or does the psu mount fan grill up where it takes air from the case and expells it out the back. which is the recommend way to install the psu?

I have seen other cases which have the psu mounted at the bottom,which orientation is the psu normally installed?

I also want to install the h100i cooler but don't think I can fit it at the top as the holes don't align, I could fit radiator on the side panel which can take two 12 cm fans but it would be awkward as I would have to remove the radiator each time I remove the side panel. any thoughts?