I get invited into a lot of crawl spaces. One of the lessons I have learned is that people will run dryer vents anywhere and everywhere. The lesson I want to pass on to you is: You should check out your dryer vent to help save electricity. You should also check it out to reduce the chance of fire and to speed up the drying time for each load. The longer the vent, the more bends in the vent, the older the vent, the more likely that there is going to be a problem. I have found vents that were 100% clogged with fibers. I have found vents sagging under the weight of the warm and wet fiber. I have found vents stretching across the entire crawl space.
A dryer vent should be as short as possible, but no more than 35′ long. I would say no more than 12′ long to make it easier to clean in the future. If you check out your vent and there is a clog you should clean it immediately. A dryer can easily cause a fire if not vented as designed.
