Thanks JBA for you your reply. Your comment was right on track as it turned out. Wish that I had gotten back to checking for replies to my post sooner than I did because I concluded that I have indeed been chasing a ghost and that ghost had a lot to do with the "attached piping and equipment...
Chasing a ghost perhaps but in the process of pressure testing a simple propane furnace installation I installed a water Column pressure gauge. Over a period of 11 hours the pressure gauge reading will go from 10" WC to 0" WC. In the course of trying to understand this I installed a manometer...