I use between 25-30 face cord per season. (October through May) As you probably know a face cord is 1/3 of a full cord if cut at 16” length. I usually cut mine between 18-20” now. Use to go a little longer but it is easier to handle at 18-20” and still makes for sturdy stacking. As you know, the amount of wood consumption depends on many variables. The temperatures, wind, firewood quality, your homes dimensions and insulation factor, of course. I use a good portion of lower BTU firewood because I cut it off my land, generally process about 20 face cord White Ash and Pine. And usually end up buying 10 face cord of some better stuff like Maple, Cherry, etc. I have a couple guys nearby who cut it to the length you want it, and deliver it, dumping it right where I need it. (That is soooooo nice! )
OWB's operate at "atmospheric" or "open" pressure and a non pressurized would work. This guy has been making open tanks for a long time.American Solartechnics, LLC. - Softank Kits
How tall? There is just under 7.5 gallons per cubic foot so with a 7 foot ceiling height, you could fit more than 65,000 gallons. I figure if you get that much water to 190* that should keep the rest of the house warm for a few hours.
