Efficiency

Efficiency

Compared to simple open fires, enclosed stoves can offer greater efficiency and control. In free air, solid fuels burn at a temperature of only about 240 °C (464 °F), which is too low a temperature for perfect combustion reactions to occur, heat produced through convection is largely lost, smoke particles are evolved without being fully burned and the supply of combustion air cannot be readily controlled.
By enclosing the fire in a chamber and connecting it to a chimney, draft (draught) is generated pulling fresh air through the burning fuel. This causes the temperature of combustion to rise to a point (600 °C/1,112 °F) where efficient combustion is achieved, the enclosure allows the ingress of air to be regulated and losses by convection are almost eliminated. It also becomes possible, with ingenious design, to direct the flow of burned gasses inside the stove such that smoke particles are heated and destroyed.
Enclosing a fire also prevents air from being sucked from the room into the chimney. This can represent a significant loss of heat as an open fireplace can pull away many cubic metres of heated air per hour.