Your pellet stove has an auger and blower fan, so you’ll hear some noise when these are operating. However, your pellet stove shouldn’t make overly loud or annoying noises like whistling, squealing, etc. So why is your pellet stove whistling, and what can you do about it?
Your pellet stove is whistling because of excessive vibration, resonance, or friction caused by an unclean auger, creosote, fines buildup in the feeder and burn pot, and failing or bad motors. Also, your pellet stove may have a design flaw in the auger or helical shaft.
You may have only one problem with your pellet stove causing it to make the whistling sound. It’s also possible the problem has multiple causes. Read on to know why your pellet stove is whistling and how to fix it.
Why Your Pellet Stove Is Whistling
A pellet stove can make different noises for different reasons.
Generally, whistling, squealing, or similar sounds are caused by excessive vibrations, reverberation, or resonance. Also, any unusual friction between the moving parts in a pellet stove can cause a whistling or squealing noise.
To be clear, I won’t be talking too much about clicking, clacking, or other noises that are almost always because of two or more parts striking against each another, loose bearings, and broken components. Still, it’s worth considering the possibility that the above may also be causing the unusual noises from your pellet stove.
The Auger Is Dirty, Causing Excessive Vibration or Friction
The auger and blower fan (including their motors) are the two main mechanical or moving parts of your pellet stove. Both of these normally create noise. However, a whistling noise is likely caused by obstructions in the above mechanical parts, since these obstructions result in excessive friction or vibration.
A common problem with pellet stoves that experience whistling sounds is a dirty auger. All types of pellets have a residual buildup inside the stove. Also, burning the pellets leaves behind ash, soot, and creosote, which can disrupt the auger’s normal operation.
The auger has a helical shaft, which is essentially a regular rod with a spiral-shaped metal strip. This helical shaft rotates inside the feeder chute. So, a dirty unclean auger can cause the helical shaft to experience friction along the feeding chute, causing the whistling sound.
Moreover, the auger’s helical shaft has a free end. The metallic part is fixed at the motor’s end with bushings and other components. The protruding part is suspended like a cantilever. Therefore, this metallic helical shaft can vibrate and cause a major resonance.
However, whistling isn’t always due to friction. Resonance or reverberation at a certain level can cause a whistling sound too. So, you have to check the auger and clean it thoroughly if you find a substantial amount of fines, soot, and creosote.
To clean the auger, you need to take it apart. If you’re not comfortable doing this, consult a professional.
Creosote and Fines in the Feeder and Burn Pot Are Causing Resonance
Creosote and fines buildup in the feeder chute can cause excessive resonance or reverberation of the auger’s shaft. The residual traces accumulate in the burn pot before clogging the feeder — specifically, the chute’s opening in the pellet stove.
Therefore, you need to clean the ash, soot, and creosote from the burn pot. Afterward, you should clean the feeder chute and auger.
Many people clean the burn pot and the feeder from the front. Although you can clean the burn pot this way, you won’t get much access to the feeder chute.
Cleaning only the burn pot area and the chute’s opening won’t prevent the whistling noise if the auger and the feeder tube around it is clogged with debris. This is why you should try to take these parts apart for a thorough cleaning.
Also, don’t just scrape out some of the soot and creosote. Use a flue or chimney cleaning brush to scrub off the hard detritus and vacuum the parts to get rid of as much buildup as possible.
Finally, clean the slide plate and other parts you may have in the hopper, auger, or feeder of your pellet stove. For instance, some pellet stoves have a fines box. You should clean these parts too.
The Pellet Stove’s Internal Parts Are Dirty, Failing, or Defective
Motors don’t necessarily make a whistling sound even if they’re defective or failing. You’ll probably hear other sounds and notice symptoms such as the blower fan not working. If the auger motor is failing, there will be fewer pellets inside the burn pot.
That said, an unclean auger or feeder chute and an overall creosote-laden pellet stove can make its parts less efficient, such as the motors. So, some components can make a whistling noise or aggravate that sound.
For instance, an auger motor may struggle to regulate the shaft if the feeder chute is dirty. Likewise, a pusher arm can vibrate due to clogging and make a sound. The blower motor can be noisy if the fan is dirty, unable to spin freely, or has other operating issues.
So, clean the internal components of your pellet stove. Then, trace the whistling noise if it continues to find out where it comes from. This approach should tell you if a specific part is causing the noise.
The Pellet Stove Auger Has a Design Flaw or Manufacturing Defect
Last but not least, your pellet stove auger may have a design flaw or manufacturing defect. For example, in some pellet stoves, the spiral metal strip around the auger’s shaft isn’t welded completely. In these models, the metal is welded near the base and at the protruding end of the shaft. However, all the other bends and turns of the metal around the shaft aren’t fused or welded.
Therefore, you may have a faulty helical shaft that creates a sound when there’s friction or vibration. I can explain the physics of why this design flaw creates a whistling or squealing sound, but I think it’s better if you watch this in action.
Here’s a YouTube video of a Harman XXV pellet stove owner, Dale Breault, with a faulty auger:
The solution to this problem is welding every joint of the helical metal strip and the shaft. You should also check if the metal strip extends below the welded part near its base. This space is usually socketed with the bushings, and there shouldn’t be any gap or space along the helical shaft.
These spaces between the shaft and spiral metal strip get clogged with debris, causing unusual friction and vibration. So, you get the loud and unbearable squealing or whistling noise.
Additionally, check if the helical strip is too big for the feeder chute.
The model in the above video has an auger that’s too big for the pellet stove feeder. The metal strip around the shaft expands when you burn the pellets on the stove. This expansion will naturally cause the metal to strike or brush against the feeder chute, causing friction and vibration.
The constant friction and vibration also cause a noise whenever the auger functions, or even when it’s loaded with pellets that go into the burn pot. Therefore, you need to grind off a bit of the metal from the edge of the helical shaft. I should note, however, that how well this solution works depends on your model.
Whenever your pellet stove whistles, check for soot and creosote buildup. Clean the burn pot, auger, feeder chute, etc. Also, check if there’s an excess flue draught drawing too much air into the pellet stove through any gaps or openings.
Negative air pressure inside a pellet stove is unlikely to make a very loud whistling noise. But if this is an issue in your case, install a flue or chimney damper. Otherwise, the auger is the culprit.