I have a walk-in shower, roughly 2-1/2 x 5 ft, 7ft high, with a shower-curtained opening. The mildew problem on the grout is pretty bad. I've seen some good articles here on controlling mildew, but I also want to install a fan. It'd be nice to not have to mess with the tile at all, and fortunately there is a hole in the ceiling for a 6" recessed-light can. So I'm thinking this fan would fit there nicely:
https://www.lowes.com/pd/Broan-1-5-Sone-70-CFM-White-Bathroom-Fan/1242821
It is rated for wet locations, as long as protected with GFCI. I don't think the current recessed light is GFCI protected, but I can add that easily myself. Accessing the area above the shower is going to be somewhat of a pain, but doable, though requiring some drywall repair.
My big question is about the fan exhaust: I don't want to run it to the outside, as it's going to chill the shower significantly, I fear. So I'm thinking about running it into the neighboring bathroom area instead (an area with a dual-basin sink vanity, which is open to the MBR) or maybe just into the bedroom itself. Is this a horrible idea ? I figure most of that moisture ends up in the vanity area and bedroom anyhow, so maybe not so bad. Though the fan exhaust is necessarily going to be just below the ceiling (since the shower ceiling is only 1ft lower than the other 8ft ceilings), unless I go to some heroic measures to have the vent come out lower somewhere. Though I'm in the humid south, the house interior tends to be pretty dry, with the AC running a lot in the summer and wood heating in the winter.
Or do I just need to bite the bullet and figure out how to vent the fan to the outside without chilling the shower too badly ?