A pellet stove is a mechanical device that burns "pelletized" fuel to produce heat. While a pellet stove is usually a reliable device, problems can occur that reduce such an appliance's ability to generate adequate levels of warmth. A stove blowing only cool air may have only a minor problem in its fuel delivery system, or it may the symptom may be just a sign of a larger mechanical issue.
Using Poor Pellets
A pellet stove burns short pressed-wood sticks called pellets for fuel. Using inferior pellets made from substandard kindling or pellets not of a sufficient size for your particular pellet stove can result in low heat generation. The stove may not produce any warm air at all depending on its size and how many pellets are actually burning. The stove will continues to run, but it will appear to produce air that's cool at best. Checking the stove's operation manual can tell you what type of fuel pellets are appropriate for your particular appliance.
A clogged hopper prevents pellets from contacting the heating element and burning. This will cause your pellet stove to produce only cool air during operation. Emptying the hopper and inspecting the chute that feeds pellets into the stove can help you eliminate a clog as the root cause of the issue. Turn the pellet stove off and let it cool if necessary before you put your hand down the hopper's chute. Failing to do so could potentially result in serious physical damage.
Stove Air Leaks
Air leaks in a pellet stove's joints and door seal can cause heated air to leak from the appliance. Significant air leaks can prevent the pellet stove from burning fuel efficiently. The system may feel warm to the touch from internal operation despite a lack of warmth emanating into the room. Wait until the system is completely cool before inspecting the stove for leaks and cracks.
Clogged/Damaged Heat Exchangers
Heat exchangers in your pellet stove move cold air to the bottom of the stove to force heated air up and out of the appliance. These components operate in a similar fashion to those in a home boiler. If heat exchangers clog, the transfer of air through your pellet stove can stagnate. This significantly reduces the amount of heat the stove produces. A licensed repair technician must inspect the heat exchangers to determine the status of a clog and the proper procedure for restoring the system to working order. These components require regular maintenance to keep your pellet stove running at optimal efficiency.