A Rumford is a great way to get great heat from an open fireplace (open fireplaces send most of the heat up the chimney.)
This link will give you a concise history and a basic conceptual understanding of a Rumford.
http://www.rumford.com/articleWhat.html
If you want to go headlong into Rumford fireplace data, photos, etc., go here:
http://www.rumford.com/
A great webpage of the construction process of a Rumford, built by masters:
Building – Rumford Fireplaces