On Mon, 16 Feb 2015 10:58:22 -0800 (PST), wrote:

Mitch, did you ever find the resolution? Found your post while doing some research. I have the same problem. I have to use a shop vac and clean out my dryer vent each week. 2.5 gallons....a week. Dryer has been SLOW to dry (3 hours a load) and now it's not heating at all. The other problem is that the vent actually runs from the dryer to the wall, underneath my home and then back up from the grass outside, and it's at least 15 feet from the laundry room to the exhaust outside. I'm terrified that we are going to have to move the vent.

You ARE going to have to move the vent. Drier vents should only go up
directly outof the drier - from there only level or down, and never
more than about 10 feet. The shorter and more direct the better. As
the exhaust coole, moisture condenses out, and it will run back to the
low point.

Whoever designed and installed that vent was totally clueless