Thought I should reply since I have a very similar situation. My house is brick sided, built in 1928, and about 2000 to 2200 square feet (depending how you figure it). We have replacement windows but no insulation in the walls and not enough in the attic. I installed my Fireview in the fall. Let me preface my experiences by pointing out that a lot of my wood was not fully seasoned. Some of it up close to 30%, which I'm sure is working against me, but the only other choice I had was to buy wood.
Anyway, I find that it can keep our house pretty comfortable in the 30s and 40s with no help from the furnace. Down into the twenties, it may need some help in the early morning (which is also when the stove is at its lowest heat output). In the teens, I find the furnace coming on just before loading even during the day. When we get down to single digits and negative temps, the stove needs a lot of help from the furnace. I should also point out that we typically keep the thermostat (in the same room as the stove) at 64 during the day and 60 or even 58 at night. I think, however, that the thermostat is reading the temperature of the wall (adjacent to some cold basement stairs) more than it is the room.
Overall, we're not staying any warmer than we did without the stove (unless we're in the room with it) but did reduce our first heating bill of the winter from $360 last year to $150 this year. Haven't seen the bill from the extreme cold of the last few weeks yet.
I had a revelation, though, when I visited my grandfather's house in northern Iowa. His stove is an older Dover, which I doubt is as efficient as the Fireview, but he was able to keep his house stuffy warm burning very small, low fires in that stove (outside temps around 0º). The difference. Primarily insulation. He built the house just 15 years ago and insulated his 2 x 6 walls to modern standards. I'm convinced the fireview would be more than adequate for us if I could afford to insulate my house properly, but I'm not sure I can a afford the $$$$$$$. I hesitate to make that kind of investment in the house because, if I sell the house in the near future, I doubt the insulation would increase the price by anywhere near what it cost me.
Regarding burn times, I get 8 to 9 hours overnight routinely even in the coldest weather, but if I tried to keep it near maximum output, like the others, it would probably be more like 4 to 6. (I'm trying to conserve wood due to a shortage.) I reload at midnight and at 8 or 9, there are more than enough coals to get the new fire going in a few minutes. If we only need, light heating, 12 hours is not difficult, but I find that I get a lot more creosote inside the box at that rate. Again, however, my wood is not optimally seasoned. Can't wait till next year when everything is adequately seasoned.
