I have an existing IXL (Heat, light and Fan) setup in a small bathroom (12.14 meters cubed). The air exchange rating of the fan meets the spec required for the room, it works and doesn't look that old. I have held a piece of toilet paper up to the fan (with the lamps taken out) and it seems to get sucked so it suggests the fan is sucking air. I took it out of the ceiling to look around for obstructions but nothing seems in the way between the outlet vent of the fan and the roof vent which is situated above the fan (it's a flat roof, so no attic space.
My question is does there need to be ducting between the fan and the roof vent ? The amount of space where the outlet vent feeds to is only a basketball or two in space (before there is insulation), however there is a path for the air to then go up the roof vent (though the path is not direct).
Also, just in terms of safety, whilst up there the cover to where the wires all fit in came off when lowering the fan - I have just put them back without putting the cover back on as this was getting too difficult and awkward to do. does anyone know if this is reason to be concerned?