Traditional Russian Fireplace labyrinthine brickwork, one of the earliest forms of masonry stove. They are substantially more efficient than open fires, but with limited air regulation waste a lot of heat up the flue when the fire is out.
rocket stove design that is better suited for indoor use. It does take some getting use to in the sense that if one doesn't stack the wood in properly it smokes back into the house. This also lends to thermal mass heating.