BobsYourUncle wrote:
Virtually every place I fill my tanks at has a flat rate whether it's empty or half full.
That's because you're here in Canada as I am where portable propane tank fill is regulated by weight rather than volume so with a 20 lb tank you'd pay for 20 lbs of propane regardless of whether that much was actually put into the tank, in which case you would obviously prefer to show up with a completely empty tank. In the US propane tank fill is generally by volume. Of all the propane suppliers around here Costco by far seems to have the best price on propane tank fill, IIRC ~ $10 Cdn for a 20 lb fill.