There's been a lot of discussion on this topic, and I've been something of a skeptic. I finally got off the couch, put down the beer, and did the calculations. During my first season, I ran a short season without storage. Second season, I had storage. Here's the bottom line: 2005-2006, no storage: 3.2 cords, 4350 degree days - .74 cords per 1000 degree days 2006-2007, with storage: 4.5 cords, 6177 degree days - .73 cords per 1000 degree days A whopping 1% reduction in wood consumption! The WAF was way better with storage, though. The house temperature was even and warm all the time, and we never ran out of hot water. We also have far fewer situations when we have to build a fire at an inconvenient time. In my world, WAF outranks efficiency any day.