The Manufactured Housing Forums

Somebody gave me a miller M1m gas furnace. when I received the furnace it did not have the combustion motor or the air vent pipe with it. I purchased a blower and used a straight piece of vent pipe to connect it in with a nipple insert in to hook the pressure switch up. I am getting a code (2 flashes) for open pressure switch. Can anyone tell me if the pipe that I replaced is just a straight thru pipe or is there something else inside. I need to know what the inside of the vent pipe looks like