While I do not have an OWB, my woodstove saves me big $ on fuel oil.
They just came to fill my tank, I am on automatic delivery based on DD. My 275 gallon tank only took 90 gallons.
I'm loving it..
If you consider that they will schedule a delivery based on DD at somewhere around when they figure you should have used 200-240 gallons of fuel.. then based on that system I figure I should have saved about 120 to 140 gallons of oil in the last 2 months. At the cost of oil here that works out to about $293.00 I saved on that one delivery, or 146.50 a month during the winter.
If you figure my wood splitter, the investment in chainsaws, (although, if you get good equipment you can pass them on to your kids) the chains, gas for chainsaws, oil, etc... the savings comes down some, but based on the life expectancy of my equipment that cost is low.
And, when you figure back in the fact I get exercise, have tons of fun using my 361.. my splitter.. and breathing clean cool air in the spring and fall, now that is PRICELESS!
I am lucky to have enough wood lot and trees, that I do not pay for my wood, other than labor, and I have enough here to last the rest of my lifetime and then my sons lifetime.
And the cherry on top is every time I split a round I smile knowing I just took a couple bucks away from OPEC!