If it's going full time, average winter WI weather, my wood furnace will turn a cord of wood into smoke and ash in about two weeks. At full military power in a real cold snap (High temps 0F or below), that can turn into less than 10 days. Thankfully, we only get about a week or so of that weather in the average winter.
I've been keeping good (almost scientific) track of my wood use this year, and since I lit the first fire on 9-18, I've used a half cord of pine and box elder, and not a bit of propane.
From my files:
9-18 to 10-5: .13 cords burned
10-5 to 10-17 .11
10-17 to 10-25 .07
10-25 to 10-28 .11
10-28 thru today, probably add another .1 cord, partway through a .19 cord stack.
At some point, I need to plug in the daily high/low temps and make some better information out of this data.
It'll be interesting to see exactly how much my use drops when I go EPA stove sometime before the end of the year. That's the main reason for keeping a close record.
A standard season's wood for me is about 8 cords, varies from 5 1/2 (last year) to 10, with lots of variables - wood, temp outside, temp inside, amount of time I spend away from home (propane takes over), etc.