When you are looking to vent a small crawl space, it is important to note that using a dryer vent is not a good idea. Although it may be very easy to install and seem like the right idea, you will find that you end up with more issues than you initially intended.
Why They are Bad
When you have a dryer vent installed into a small crawl space you will find that the ceiling may begin leaking. This is due to the fact that the dryer vent is too far away from any source of air flow and that it gets cold very easily. This is an issue because the when moist, hot air runs through the vent, condensation is going to form on the pipe. As well, you will find that the vent system fails to do its job of ventilating the space. This is because dryer vents build up lint and dust and dirty very quickly. They need constant attention and have to be cleaned out often.
Fix the Problems
In order to fix the venting, you need to make sure that the vent pipe stays warm. This is a very easy job for a drywall repairman. it does cost a bit of money, but it will save you from having to pay three times as much money to replace the water damage in your ceiling.