Why Would Smoke Fill the Fire Box on a Pellet Stove?

Blockages

• A clogged air intake hose can stop the flow of air and cause smoke in the firebox of your pellet stove. If this happens, you’ll be able to see black smoke at the vent cap and, within a few hours, the glass on the window will be black with soot. In addition, the flame will look lazy and have black tips. If ash is clogging the heat exchangers or exhaust flow paths, you’ll need to clean the heat exchanger tubes, side exhaust channels, rear exhaust channel, floor exhaust channel and side heat exchanger and exhaust blower assembly. You may also need to clean the vent system, if something is plugging it.

Air Leaks

• Smoke can leak out of the firebox and into your house if there are air leaks in the stove. Make sure that the firepot forms a good seal with the firepot base and that there is no ash between the firepot and the base. Inspect the area around the door and the ash pan and ensure that the ash pan gasket touches the face of the stove throughout its entire length. Test for leaks by moving a flame around the door after you turn on the stove without building a fire in it. If the gasket is leaking, the flame will be drawn toward the leak.

Fuel Problems

• Pellet stoves may smoke if you try to burn old pellets or wet pellets. Another problem occurs if you pour too many pellets into the burn chamber at one time because that reduces the amount of available air. Burning the wrong fuel in your stove can also cause a dirty burn. Pellets come in either standard or premium grade. Stoves designed to burn premium grade pellets don’t run as well when standard grade pellets are burned.

Power Shutdown

• Pellet stoves require electricity in order to operate. If you lose electrical power, the combustion blower on the stove will shut down. However, the pellets in the stove will continue to smolder and the smoke they produce may spill into your house if the exhaust vents lack vertical sections that provide a natural draft. Using a battery backup can minimize this problem. In addition, the pellet vent should have a vertical run of at least 5 feet.

Other

• Your flue should be cleaned out every time you burn 1 ton of pellets. A dirty flue cuts off the flow of air and can contribute to the formation of excessive smoke. Air flow is also restricted if ash isn’t regularly cleaned out of the firebox, if the hopper lid is left unlatched or if the wear plate is missing.