Adding Fantech inline exhaust system to existing bathroom
We are having moisture issues in the master bathroom because the existing fan is not moving enough air. We like to take long hot showers, and recently have notices condensation running down the walls. The existing fan is rated at 50 cfm, but is a real POS, and looking back at the pictures from construction it appears the duct may not be properly installed. We are beyond our 1 year home warranty, plus I have no desire to ever deal with the builder again. Rather than replacing the existing fan with a higher volume unit, I would rather start fresh and run all the ducting myself (or hire a knowledgeable contractor) so I can ensure the work is done properly.
After reading a bunch of posts and reviews online I would like to install a Fantech system as it sees they are well regarded. To mitigate the moisture from the shower I would like to add a new exhaust port above the shower, replace the existing fan with a Fantech exhaust port, couple both together with a Y-duct and vent through the roof. Our bathroom is roughly 10'x12' (not including the shower) and a 5'x4' shower off to the side. My first question is: should I place the exhaust port over the shower stall or just outside the shower stall? Is it worth adding an additional exhaust port or should I just stick with the one I have now and replace with a more powerful unit?
Now for the installation. We have access to the area above the bathroom as it is an unfinished bedroom that we plan to turn into a guest bedroom down the road. Since we plan to use it as a bedroom I want to route the ductwork so that it will not interfere later when we plan to finish out the room. I pasted a link below to some pictures I put on Picasa. In the pictures I drew up some rough sketches of where I would like to run the ducts, how I plan to couple the new exhaust port with the existing, blower location, and layout of the framing. I came up with two ideas:
1) Run the duct about 5' back between the floor joists and then penetrate the floor and run up along the wall of the bedroom closet. Run a duct down to the existing fan location. Above the closet couple two ducts together with y-joint, run to blower, and then out through the roof. I sketched this option in Blue in the pics.
2) Run the new duct through the webbing of the existing floor joists, couple up with the existing fan, and then out through the roof. I sketched this option on green in the pics.
I'm not too keen on the second idea as it would require me to cut a ~7" hole through the I-Beam webbing, which will reduce structural integrity of the beam. The benefit to this option is that I don't have to climb as far up on the roof to install the outflow vent, and the duct runs are much shorter.
What kind of ducting should I use? Fantech recommends the flexible insulated duct, but I found this other site were a guy used PVC piping.
I would appreciate any suggestion including ideas I have not thought of. I appreciate any help you can provide.
Here is a link that might be useful: Pictures