Propane regulator and an empty tank

[JeffCross]

Had an unusual problem. I usually open both of my tank valves so that my propane will continuously flow and the valve will switch between tanks automatically. This is the first time that I actually "drained" a tank. The hot water heater sputtered a couple of time and the indicator went from green to red and I just switched the valve.

The strange thing is that my propane monitoring system (Mopeka) said I had 20% left in the tank. (It was 70 degrees or so at 9000 ft). My initial guess is that the indicator was bad. Today when I went to the local ACE for a fill up, there clearly was 20% left in the tank.

Had I closed the full tank and forced the appliances to try and really empty the low tank, would that have worked? I didn't want the fridge and potentially the furnace or fridge to sputter, so i switched. Is this common for a tank not to completely empty? Was altitude a potential issue?

Not earth shattering...... just curious.

[SSquared]

I have never noticed any appliance sputtering due to low propane or the change-over happening. I have camped as high as 10,000 feet. I'm sure I have had change-overs happen while camped in the Colorado mountains but I don't specifically remember anything about those changeovers.



Having it leave 20% in the tank at change-over time is not normal. When I have a tank filled after a change-over, the fill amount is usually within 0.1 or 0.2 pounds of the expected amount.