Structure

• Inserts are steel or cast iron fireboxes that fit directly into a masonry or factory-built fireplace. They are normally fronted by safety glass that offers a view of the "fire." An element inside the firebox heats the temperature of the permanent, nonburning logs within the fireplace, while an internal fan disperses heat into the room. Heat elements plug into standard electrical wall outlets.
  
  

Efficiency

• Fireplaces fitted with inserts are more efficient than traditional wood-burning structures. The outer shell of an insert works with the internal fan to push most of the heat into the room instead of allowing it to escape up the chimney.
  
  

Other Advantages

• Because a heating element replaces traditional fuel, there is no cleanup of ashes, soot and creosote. Additionally, many electric inserts come with a lighting option that provides the illusion of a fire during warmer months without the accompanying heat.