I have just purchased a house with a bathroom vent that exhausts into the attic. I would like to put in a gable end discharge. The roof is very steep and two stores up so that is not really an option. My question is, are there length limitations for ducting from the fan to the gable? I have read lots of posts on here and every one says you can duct to the gable with in reason, but how much is reason? Thanks.