My bathroom fan was getting old and noisy like they tend to do, so I decided to look into replacing it. Another issue is where it is vented is not exactly the smartest. I have a split level home so it was venting in the soffit that meets the lower roof. No wonder I had 2 foot icicles and the gutters literally filled with ice! So I had to vent it somewhere else.
I looked into going through the roof, but was told by a roofer this is a bad idea, and it was actually something I was suspicious about. You have cold air sitting inside a pipe (no matter how well insulated it is, some will get in over time) then you turn the fan on, and hot and possibly moist (shower) air is rushed through this cold pipe. What happens? You got tons of condensation and eventually dripping water inside the pipe. So I decided to look at venting it through the soffit, but on the other wall (washroom is in a corner). Another problem: Due to the roof slope, it is impossible to actually reach that spot without cutting a hole in the roof. This would make maintenance of the fan unit very difficult.
Conveniently, the hot water tank chimney chase is very close to that area... So I decided to vent it through the basement wall by running a pipe through that chase. This is probably very uncommon, as I had trouble finding any info online on other people doing this.
The full setup for this involves a vent intake in the bathroom, some insulated flex pipe that goes from the vent to a ABS pipe (in the attic) that goes down the chase, then back to some flex, the fan unit, then flex then metal ducting to go outside like a dryer vent. The reason for the flex near the fan is to give it some play, and make it fairly easy to maintain. I'm sure these get full of dust as much as any other fan. I looked into the option of adding some kind of filter but it would have been way custom, and look bad. I like the look of the basic rounded vent.
I'm not quite done yet, need to run the metal pipe to vent outside then I need to fix a leak in the attic where it connects to the ABS. Can't wait to be done in the attic, hard to get in/out of there and overall painful to work. Very crouched space and only being able to crawl on the joists makes this quite the workout. Lastly, I have to patch the hole where the old fan was. Debating on putting some kind of access panel there, as there is a junction box. It's technically to code, but realistically, it's not really accessible from the attic unless you're a midget.
Anyway, enough yapping, and some pics: