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propane gas line restricted, what came out?
In a seasonal cabin , replaced an antique direct vent wall furnace (never even turned old one on, customer just wanted to upgrade) with a similar type wall furnace. Cabin has propane tank with combination 2 stage regulator on tank, copper line buried underground apx. 20' then exposed below structure and into furnace. On startup, incoming gas pressure was 10" (same at regulator outlet at tank) yet when firing incoming gas pressure lowered to 3"and same for manifold, yet had 10" at regulator outlet. Determined there was some blockage? Checked for obvious kinks on exposed piping (found none). I disconnected copper line from both regulator outlet and furnace, used air compressor to blow line out. Could "feel" the air also was restricted blowing through, until it let loose. Once clear,reconnected and leak tested, supply and manifold pressure perfect . What came out is the question I have: the debris color was shiny emerald green, hard like stones yet crushed up with force. I first thought it was emerald ash borer beetles shells but that would be impossible because the tank and line have been in place for 40+ years (regulator was replaced by propane company a few years ago, but not left open to atmosphere at any point). Unfortunately, I did not take any pictures of the debris, unfortunately. Any one seen hard emerald green deposits build up and restrict copper propane line? I hope I described it well enough.
Thank you, Pat