CountryBoyJohn, I knew there was probably a formula out there but I guess I never thought to ask anyone. As I was writing that post last night it was making me kind of sick thinking how much I'd be spending on propane. Yet, it was making me quite relieved at having that boiler out there. Never thought to mention this last night, but the man who I got the $2.89/gal from, told me that the supplier's cost was $1.70. While that markup may seem ridiculous, I don't hold that against a supplier. There is a lot of money involved in transports, storage, delivery, fuel, employees, etc., etc., and you can't expect them to do it for free. It sure does make me feel good that those dollars aren't coming out of my pocket though. One more thing, last Saturday, I talked to one of the local company's transport drivers. He told me that they had already moved more propane as of last week than the total sold the previous winter. I told him I was going to hug my boiler when I got home, lol.