A friend of mine has been having trouble with his propane fired boiler. The flame is signifigantly higher than it should be. I checked the incoming gas pressure at the boiler - 11" w.c. before the valve, with about 8"w.c. after the valve. Pressure should be 3-4"w.c. after the valve. He called his gas supplier. They sent a service guy out who checked everything and said he couldn't find anything wrong. Then my friend told the service guy that I had checked the valve, and told him what I had found. So the service guy checks and says, "yeah, the valve is bad." So, they replace the valve. ($200.00) Now the flame is not nearly as high, but still higher than it should be. Then Mr. Service Man tells him that his gas lines are worn out, and they can replace them for "around $800.00." Thing is, everything else in the house works fine; gas dryer, gas water heater, and gas range/oven. The gas lines are 3/4" soft copper. Now, I'm a refrigeration mechanic by trade, and I don't have alot of experience working with gas units, but I think I smell a rat. I have seen copper get eroded from the inside out by chlorine water, but am unaware of this problem with propane. Is this possible? Does propane erode gas lines? And if it does, why would everything else in the house work as it should? I have heard story after story about this particular gas supplier and their service guys milking major bucks out of unsuspecting homeowners.