Top Feed vs. Bottom Feed
When choosing a wood pellet stove, it is important to understand the type of pellet “feed” system. Wood pellet stoves typically have two ways of “feeding” wood pellets into the burn pot:
Top feed or drop feed is the most common system. Pellets are transported from the hopper up a cylindrical tube by an auger, which looks like a large drill bit, then drop or slide down a ramp into the burn pot. Each drop of pellets may look like a small splash into the ash bed and may cause small sparks to fly in the stove. Some believe that this produces a less realistic stove-like flame. Some of these drop-feed stoves have less flexibility in the pellet type and quality of fuel they burn. Examples of drop feed stoves are Lopi, Avalon, Quadra-fire, and Whitfield.
Bottom feed or push feed, while being less common, is believed to be a more reliable and sometimes more efficient feed system. Pellets are transported by an auger and pushed into the back of the burn pot, creating a tight mass of fuel which burns more completely. As the fuel is continously pushed in, it forces the ash towards the ash pan reducing the potential for clinkers. Bottom feed stoves often allow more flexibility with burning lower-quality pellets, as well as corn and other biofuels. They produce a more realistic, steady, wood-stove-type flame. Harman is the most popular example of bottom feed stoves.