I live in a split level house @ 2,300 square feet. I've got a Harman fireplace insert with a 135CFM blower fan on it. The stove is installed lower level. When I first fire it up, it seems to take a FULL 20 hours or so for the whole house to stabilize. And then it's Toasty City! It heats our entire home....though the tradeoff is that even if it's 5 degrees outside, ya better wear just shorts and a t-shirt when doing anything downstairs.
I have 4 cats and they LOVE it!
The heat naturally flows to the upper level.