Sycamore guy -- I'm sure the project would be over my head. As I said, the bathroom is on the first floor with no access to the outside. This duplex is a twin... there's another one right on the other side of the wall, so really the only option would be straight up through the roof, or else I'd have to somehow run a duct out the bathroom, through the bedroom on the surface (because of the fire wall between the two buildings), and then out the rear wall of the bedroom. As far as the roof goes, first of all that would require (I'm sure) chopping out the newly re-finished second floor bathroom wall, plus I don't do ladders higher than 6' stepladders so roof access is out of the question. There's no attic. Housekeeping -- I wasn't here when the ___?___ was removed. I never saw it. I don't understand the newspaper reference, though. The newspaper was just used as filler in the wall so that the wall could be plastered up, and yes, it's now all removed. Whether or not is was a dehu is an interesting question. I've never actually seen or used a wall mount dehu. Would it be "big and bulky", and possibly screw onto the threads of a 2" pipe that go up to the roof? If so, I'd be willing to guess that's what it was, and that's what it has to be replaced with. Thanks all for the quick responses!

brickeyee-a remote mounted fan appears to be what I'm looking for. Do you know of any nice ones? Our kitchen is not very big (11' x 12'), so a modest size vent fan would do, something very quiet to draw out smoke, etc. It gets cold here in the winter, so we need an exterior vent that would prevent back draft. oldhousegal-those laurelhurst fans are beautiful, but we already have an antique grill.

there are two separate issues that need to each be addressed entirely on their own. in all of this, remember that your fan duct is a chimney and reacts accordingly. you usually have warm air flow and waste even when not "using" it. if you have condensation and it's all in cold weather, insulate the thing. Not with that trendy gimmicky thin plastic junk but with a whole lot of plain old fiberglass. a lot of it. reseal any seams first, perhaps with brush on goop and fiberglass mesh. the water damage is a separate deal and I would not be any way qualified to suggest anything concrete without eyes-on. both issues do seem to be from poor installs. the s-trap is funny, though.

As for fan-lights in the shower, it seems ineffective to try to remove water vapor laden air from the shower since most of it will condense on the walls before that can happen anyway. My goal is to remove humid air from the vanity area and allow fresh air drawn from the door undercut to reduce fogging of the mirror and window glass. The entire bathroom will eventually dry out if you use a fan with a built in timer and/or constant low speed feature like Panosonic's WhisperGreen series. I have yet to find a fan-light combination that performs as well as separate units. Here are my criteria: no CFL or LED lamps (LED inappropriate in a bathroom; CFL inappropriate in a house) Max sound rating .8 sone max grille size 13x13 flush with ceiling variable speed fan with timer Panasonic makes a recessed spotlight-fan combination (FV08VRL1) but it uses a CFL. I suppose a halogen PAR lamp could be substituted because the CFL is probably only needed to get an EnergyStar rating but I am not comfortable recommending it. To reduce fan noise it is important to reduce back-pressure by using larger metal ducts.