I'm looking to purchase a woodburning insert but I can't figure out what heating capacity to aim for. We have a 3-story house, about 800 sq ft per level, and the fireplace is on the lowest (and coldest) level. I've heard that we should pick an insert with a heating capacity of no more than 1,200 sq ft because otherwise the lowest level of the house will get too hot (or the insert just won't be as efficient as it could be). Is that the case?
Ideally, I'd love to have some of the heat rise up to the middle level. Is that realistic? Will an insert with a higher heating capacity be better able to warm the middle level, or does that just depend on how well air moves in our house?