hi do you know when you know you read something in your book, then later on you need this info you go back and can't remember under what topic was it? dryer vent is maxed to a certain lenth in ducting hose and with elbow reduction if it's 45 or 90 degree elbow the max span on duct changes to a lesser lenght. 1. any info on that? 2. what is the standard for the hight of the outside dryervent , the one I have is against the floor. witch would make it even with the back of the dryer vent exit. can't tell if the hose going up the cieling and at the out side wall going down to the floor and out of the house, if that the case is that ok.