It was just a fluke. You need to include your equipment repairs into your cost regardless of how they happened. Otherwise you are not being honest with what wood is costing you. If you were selling firewood, you most certainly would include it as a means to lower your tax burden. It's not dumb at all. In fact, it would be dumb not to.

Also, you can value your time as you see fit. You can measure that however you wish: money, time away from kids, time not fishing, etc. It's your time spent. Wood is time intensive. That's the tradeoff. If you don't value your time dealing with wood, it will always be cheaper in your own mind. Put a value on it plus include costs like equipment repair and maintenance to obtain the wood and you're into the more expensive or break even area compared to using other energy sources. In my case as propane prices keep rising, that becomes less true. But it's not there yet.