Hi folks please help if you can I am going through the poured wall of my basement starting at the heater I have an adapter then a clean out T then I have 7ft of pipe then a 90 elbow then a 1ft piece to get through the wall .Because it is not 3ft off the ground Imust use another 90 to turn up and then 1 more to put the cap on . my ?? is because of the 15% loss of draft for each 90 how high vertical should I go up ?? Sorry to be so lenghthy but please help. THANKS.