After my propane supplier refused to came and check my long time, ongoing low pressure problem inside, I hooked up a gauge right at the valve behind the range and got 7.5 WC. They checked the regulator at the house and it checked out ok, years ago when they did check inside it showed low pressure. For many years the hot water heater sounds like a jet engine when it first starts and for a few seconds (it ruined the old one), the old furnace needed the jets to be rodded out with a paper clip every so often and the top burners on the range would soot up, also the broiler would not work properly and needed the stove to be on high for a while to even light. Where do I start? The tech said that I might have a restriction in the 1/2" piping, is that possible?