First, the fireplaces originally mentioned are likely a heat sink — that is, losing heat — unless they are a Rumford or Bell Rumford design which is energy efficient. (Just Google it.) Second, consider a pellet stove in your primary living area. I heat most of my house with a small pellet stove. One winters’ worth of pellets costs about as much as one month’s worth of propane heat. I use my high energy efficient propane furnace on those rare occasions (usually in January) when the pellet stove just isn’t enough, and at all other times as backup. Set to 55 degrees, it comes on if the pellets run out at night or I’m away from home. Good life to everyone!