I was just reading threw your post here and wanted to just clarify some points of difference between propane and natural gas.  First both are delivered into your house at a low pressure this is measured in inches of water column.  Essentially the pressure gets dropped down outside the house by a regulator to about a quarter of a psi.  Another difference is that propane has more potential thermal energy about 2.5 times the amount in natural gas.  So you have to use...