I have a question on gas piping. I have 2 packaged AC units(Comfortmakers). The gas piping to both of them, which are on the roof, is 3/4 inch, then there is a 3/4 to 1/2 inch elbow and then the 1/2 inch shut off valveand then a 1/2 OD inch flex pipe which is 3/8 ID. Is this to small for a 100,000 & 60,000 BTU furnaces in the Packaged systems? I did not measure the distance to the systems, the 60000 BTU furnace is approximatley 100 feet, the 100,000 btu furnace is approximatly 50 feet away from the main gas line. It just seems that a 3/8 ID pipe may be small. Can anyone give any input?