Traditional wood burning fireplaces use a passive draw system to remove combustion from the home. Tempered air, from inside the home is used to supply the fire with oxygen. The heat of the fire rises through the vertical flue and creates a lift similar to hot air rising in the atmosphere. This pulls the various particles of combustion, through the flue system and out of the home. Manufactured, modern wood burning fireplaces utilize a metal double-wall, air-cooled flue system.
Efficient, free standing wood burning fireplaces and inserts have increased in popularity in recent years due to technological advancements in this product, along with increase in consumer demand for a efficient secondary source of heat.
There are two elements that increase efficiency of modern wood burning fireplaces:
1) When the majority of the combustion air is pulled from outside the house.
2) Ability to Control the combustion air flow in order to extend the burn time of the wood.