Installing a new Whirlpool gas dryer. Gonna stack it on top of the new whirlpool washer. I have to run a completely new vent as I have moved the dryer from it's previous location. Is it OK to vent the dryer out the roof? I thought about venting it out the soffet but read somewhere that kind of venting is prone to putting humid air back in the attic. If I vent out the soffet the vent run will be about 25' with 3 90's. Venting out the roof about 12' and one 90. Any suggestions?