Aside from keeping the warm air from escaping, the doors act to keep the hearth clean just as a fireplace screen used to do in the olden days. With the doors closed, ashes and embers don't scatter about the room, keeping the carpet or rug clean and scorch-free. The doors also have built in devices that divert air towards the bottom of the fireplace. These vents make the fire burn brighter and easier to light.
Winter is just around the corner and the weather is beginning to grow a little colder with each week. It's almost time to get the fireplace going again, and a fireplace blower would be a great addition to your house this season. I don't know about you, but I always find myself as close to the fireplace as possible during those cold winter days. My fireplace is in the den of my house, and if I'm on the other side of the room, I simply won't feel the warmth of the burning fire.