I moved into an all electric house 1976 in a low cost electric area and had one year's heating costs before I installed a wood stove. Figured that it would take at least 5 years to recover all the capital costs. It turned out that I recovered all capital costs--stove cost, installation costs, chainsaw, etc. in 3.5 years. I didn't dig them out but as I remember capital costs were around $900 and a cord of free firewood cost me an average of about $25 for gathering it. After the first 3.5 years my costs were about $75 per year (3 cords) for heat. Took the stove out about 5 years ago because of my wife's asthma and changed to gas. My December heating bill is now above previous all year heating cost.
I wouldn't plan on recovery of capital costs in
3.5 years now, recovery in a 5-7 year period is easily possible if one does all the installation and buys modestly priced equipment and gets free wood.