My roof has two DX11VSR ventilation fans that were installed about a year ago.
I have had repeated issues where rainwater gets into the ventilation ducts attached to these fans and then leaks through the ceiling. I have been able to confirm that it is the fans that are leaking by running a hose pipe with sprinkler attachment over the top of the fan covers at a vertical angle. This reproduces the leak in the exact spot that I see the leak during heavy rain, but despite all my efforts I can’t work out how the water is actually getting into the vents. The subcontractor who installed them made several ineffective attempts to fix leaks and has now stopped operating.
I checked the manual for this fan and in the troubleshooting section it says that if the fan is leaking then the drain spout could be clogged. However there is no indication where the drain spout should be!
Can anyone provide any guidance on further troubleshooting this leak and things I can try to resolve it?
Edit: I have added side views of the fan. It does have a curb. The curb is metal, but the screws on the fan base visible in the south and north views are going into wood - I think there is some wood piece on top of the curb. One of the "fixes" the contractor attempted was to cover the join between the base of the fan and the curb with mastic. There is no pooling of water around the join between the curb and the roof.
Also here is a video showing the leak from inside the house and then showing how the water was falling on the fan.