I added a 95% efficient propane furnace to my existing system this summer giving me a 3 fuel heating system to burn whatever I decide to use. The existing early 80's vintage Charmaster wood/oil combo forced air furnace was still running strong, but I wanted to gain the true backup convenience of a high efficiency propane furnace. So far this year, I have never fired the oil burner. The propane has only been run 2 days, the day after Thanksgiving and today, so I could let the wood fire in the Charmaster totally burn down so I could remove and clean the flue pipes. I've been burning wood strictly from my property since mid September. The new propane company even gave me a nice courtesy call the other day to see if I needed gas, they were concerned that I had not called to order any and suggested I should check my tank level. At this rate that first fillup last August could last years!