Pellet Stoves Inserts - Convert Your Drafty Fireplace Into an Efficient Heating Source Pellet stoves are either free-standing heat sources, or fireplace inserts that install into your existing fireplace. They can be extremely efficient and burn compressed pellets made of wood byproducts like sawdust. They are also deemed "green" because https://www.fireplacesandstove.com/categories/pellet-stoves/2