Mentioned in this thread http://www.hearth.com/econtent/index.php/forums/viewthread/14398/ “Some of the PAP, like Kitec has a larger id. Figure 10- 11 GPM through that tube, about the same as 1” copper tube.” master of sparks . I am not familiar with the term PAP. Does this mean that the 92,000btu I need for the house would be transferred adequately by this 1” Kitec? If so that would be a big savings compared to the planned 1 ¼” pipe I was going to use considering the 175 feet distance of run from the Garn boiler to the house.