• Traditional fireplaces provide an inefficient source of heat for a home. A number of companies produce special fireplace inserts, which are metal boxes that sit inside the fireplace and use blowers to move heat around the room. Fireplace inserts that use pellets for fuel are much more efficient than a normal fireplace, but come with their own set of disadvantages.
  
  

Cost of Fuel

• The experts at ConsumerReports.org say that in most cases, pellets are less efficient that seasoned hardwood, no matter what type of appliance the fuel is burned in. Most pellet suppliers sell them by the ton, requiring plenty of storage space and a few hundred dollars to spend at the beginning of winter or when you run out of fuel. Unlike wood, pellets can't be fabricated at home or harvested from your own land. Availability is also an issue. Pellets may not be available in your area, so check that you have a steady supplier before installing a pellet fueled fireplace insert.
  
  

Less Efficient Than a Free-Standing Stove

• Free standing pellet stoves radiate heat from all sides of the unit into the room. Much of the heat the back and sides of a pellet fireplace insert is absorbed by the fireplace itself. This lowers the heating efficient of any type of fireplace insert. However, inserts make up for this loss by using electrically powered fans and blowers to force more hot air into the room. Fireplace inserts also take advantage of the heat resistant hearth and chimney most fireplaces have. Gas powered or display only fireplaces may not be able to accommodate a working fireplace insert.
  
  

Requires Venting

• All appliances that burn some kind of fuel produces fumes, soot or smoke and require venting. The Encyclopedia of Alternative Energy and Sustainable Living warns that your chimney may be too damaged or drafty for use with a fireplace insert. This will require either running closed vent pipes up the chimney, or repairing and sealing it. The alternative is to install a separate vent pipe, but if you are willing to do so you might as well install a free-standing pellet stove. If venting is not an option or too difficult, an electric space heater may be a better choice.
  
  

More Susceptible to Damage

• Pellet fireplace inserts contain a variety of moving parts, both mechanical and electrical, that are susceptible to wear and damage, according to the U.S. Department of Energy. A cast iron wood stove has few moving parts and must rust or corroded to be damaged, but the fans, blowers and automatic feed devices on a pellet fireplace insert are not as hardy. These appliances will require regular maintenance and repair,