Just bought my first house with propane (LP) heat and hot water. What a learning experience. I have a 500 gallon buried tank (didn't realize it was owned by one propane provider and I was locked into that dealer unless I bought the tank) with a guage that reads in percentage. After I signed up for the "keep full" option (thereby saving a dime per gallon), the dealer came out when my tank was reading 59%. I wasn't home when it was filled.
The little gauge on my tank (yes, my tank. I bought it.) moved from 59% to
85%. Subtracting 59 from 85 and multiplying by 500 led me to believe they had pumped in ~130 gallons.
The dealer's printed ticket showed 183 gallons.
Logic tells me that Boyle figured out the relationship to volume and pressure in the 17th Century, and that as the volume of gas (in the void above the liquid) increases, the pressure is reduced and the gauge is a simple pressure gauge.
Dealer said maybe the gauge was sticking. Could be, but, as a newbie to propane, I checked that gauge almost every day and saw it drop incrementally. It took from December 2nd at 70% (move in day) to January
3rd to drop to 59%, and it was, as I said, quite incremental. It didn't just suddenly go from 64 to 61. In fact, you couldn't see the movement except over several days. And, it had not bottomed out and stayed at 59% for a week. Does that sound like a sticker?
For comparison purposes, this is in central North Carolina. Prices I was quoted for propane ranged from $2.249/gallon (price I paid at closing), $2.049 from the fluke who owned the tank, $1.999 from a competitor for "on call" if they "took over" the tank, $1.899 for autofill if they took over and $1.699 for autofill if I owned the tank.
So, does anybody know how a propane gauge operates, and am I the only person who thinks I should be able to use the delta percentages to derive approximate delivery gallons?
Oh, to add insult to the injury, not only does North Carolina have the highest motor fuel tax in the southeast, and one of the higher income tax structures, there is a 3% sales tax on electricity and natural gas, but fuel oil and propane buyers pay the full 7%. That's another rant, though.
Thanks for your replies