A bathroom exhaust fan should produce 4 air exchanges per hour. Your bathroom is 7 x 7 which is 49sq.ft Assuming an 8' ceiling the total volume would be 49 x 8 = 392cu.ft We want four complete air exchanges per hour so that would be 392cu.ft x 4 = 1568cu.ft per hour. There are 60 minutes in an hour so we divide 1568 by 60min and it equals 26.13cfm. You currently have a 50cfm fan, which is twice the size you really require yet your having problems with the mirror fogging up. I suspect your problem is not the fan. Nature abhors a vacuum therefore a fan cannot push air out of a room unless there is provision for an equal amount of air to enter the room. You can test the theory by running the shower and leaving the bathroom door slightly ajar to allow more air to enter the room. Generally they make a slightly higer gap under the bottom of a bathroom door to allow more space for makeup air to enter the room but in some circumstances that does not provide enough makeup air. The solution then is to install a duct through the wall to an adjacent room and put a grille on either side. That will allow the additional air.

i've posted in the bathroom forum under "what a disaster" and i thought i'd bounce it in this lighting forum. i have a small bathroom that was just re-done. the shower doors are really high (78" - kinda a mistake on my part) and between the (beautiful) crown molding, the fan over the shower and the top of the shower doors all gathering on the ceiling (or close to it) i dont think i could go with a ceiling light. i really wanted a ceiling fixture, for that layered lighting effect and the electric is already on the other side of the sheetrock, ready for a fixture. i do have a 3 fixture light over the vanity and honestly it provides adequate lighting for the room. i looked on the internet and saw some flushmount ceiling fixtures... not the ones that are bowl shaped, only because i think the depth is too big...but the ones that look kinda flat. should i just chuck the idea of having a ceiling light or do you think a real low profile fixture would be worth it? like i mentioned, the electric is all ready to go...(like a road to nowhere?)

That's plenty of room for a ceiling unit. If you're going to spray in foam, just box the unit in with the clearances suggested by the manufacturer. It's possible, since it includes a heater, that there should be clearance not only on the sides, but the top as well. If there's no foam on top of the unit or if the foam is less than 6" there, that's no big deal for such a small area.

You will never see a bathroom exhaust fan installed 2ft off the floor , due to inefficiency . I am afraid you will have to provide the necessary depth , by lowering the ceiling , or create more depth in the wall to accomodate the fan's installation at the appropriate location . I would definitely go with ceiling location . A wall location -- as close as possible to the ceiling -- would be considered only as a last resort .