 Is it as big an issue for a near horizontal run through a wall (which seem very common) as it is for a run on an angle? B bholler Chimney sweep Staff member Jan 00, 0000 00,000 central pa Jul 00, 0000 #0 chhamilton said: Is it as big an issue for a near horizontal run through a wall (which seem very common) as it is for a run on an angle? 