Fluctuating burn, high to low, high to low,. . . . .

[Ranckie]

Greetings,
I have a Harmon Accentra Insert with what I think might have a pellet feed issue, but I’m not sure. This stove was installed in 2007 and I have been doing all of the annual cleanings (as per the book) and all maintenance myself these past 18+ years that included all of the normal pellet stove issues that most pellet stove owners have to deal with, things like trouble shooting, replacing igniters, ESP sensors, augers, and an auger feed motor, and each time an issue came up I’ve been able to resolve it., and it has been a great stove. I've been using the same 65/35 blended pellets for the past 16 years with excellent results and I've always burned it on Stove Temp with no thermostat

About three weeks ago, after about four very successful burn seasons, it started burning poorly like you’d expect with slightly damp pellets or a dirty or bad ESP sensor so, two weeks ago I did the obvious and pulled the stove, (not easy for an 83-year-old pulling on a 450 lb. stove) and cleaned the sensor, and afterwards it still burned the same way. So, I then purchased a new sensor (black wire) and a week later on 02/28/26) I replaced that. Now, while it seems to be a bit better, it’s still not the same as it was before 02/03/26.

On startup, it burns fine with a nice hot high flame but as time goes on when the feed light comes on, the flame doesn’t seem to respond in kind and it slowly starts to die down and while it’s in that low fire state, it’s throwing more of those ‘unburned fire flies’ (which means dirty burning) and that messes up the stove far sooner than it would if it was burning correctly. Then it will usually drift back and forth for a while, like a nice high flame and then low, and back and forth.

I have a new control board and I’m about ready to change it to see if it makes a difference, but my gut tells me that while the feed light is on, I’m not sure the auger is turning as it should since the auger could be binding. Those auger motors are impedance motors which means if something binds or jams the auger, the motors will simply sit there with no rotation and just hum without burning out. A couple of years back I made up a test light and connected it in parallel with the motor leads to see if the motor was getting power when the feed light was on and I was able to determine that it was. Unfortunately, that doesn’t tell you if the auger is turning and therein lies my question.

Is there a way to determine if the auger is actually turning when the feed light is on? I tried looking through the flame to see if the auger was turning when the feed light was lit but it’s hard to see through the fire because you’re trying to see if the tip of the auger is turning, located way in the back of the burn pot.

Any help would be most appreciated. Thanks.

 

[Whitenuckler]

Greetings,
I have a Harmon Accentra Insert with what I think might have a pellet feed issue, but I’m not sure. This stove was installed in 2007 and I have been doing all of the annual cleanings (as per the book) and all maintenance myself these past 18+ years that included all of the normal pellet stove issues that most pellet stove owners have to deal with, things like trouble shooting, replacing igniters, ESP sensors, augers, and an auger feed motor, and each time an issue came up I’ve been able to resolve it., and it has been a great stove. I've been using the same 65/35 blended pellets for the past 16 years with excellent results and I've always burned it on Stove Temp with no thermostat

About three weeks ago, after about four very successful burn seasons, it started burning poorly like you’d expect with slightly damp pellets or a dirty or bad ESP sensor so, two weeks ago I did the obvious and pulled the stove, (not easy for an 83-year-old pulling on a 450 lb. stove) and cleaned the sensor, and afterwards it still burned the same way. So, I then purchased a new sensor (black wire) and a week later on 02/28/26) I replaced that. Now, while it seems to be a bit better, it’s still not the same as it was before 02/03/26.

On startup, it burns fine with a nice hot high flame but as time goes on when the feed light comes on, the flame doesn’t seem to respond in kind and it slowly starts to die down and while it’s in that low fire state, it’s throwing more of those ‘unburned fire flies’ (which means dirty burning) and that messes up the stove far sooner than it would if it was burning correctly. Then it will usually drift back and forth for a while, like a nice high flame and then low, and back and forth.

I have a new control board and I’m about ready to change it to see if it makes a difference, but my gut tells me that while the feed light is on, I’m not sure the auger is turning as it should since the auger could be binding. Those auger motors are impedance motors which means if something binds or jams the auger, the motors will simply sit there with no rotation and just hum without burning out. A couple of years back I made up a test light and connected it in parallel with the motor leads to see if the motor was getting power when the feed light was on and I was able to determine that it was. Unfortunately, that doesn’t tell you if the auger is turning and therein lies my question.

Is there a way to determine if the auger is actually turning when the feed light is on? I tried looking through the flame to see if the auger was turning when the feed light was lit but it’s hard to see through the fire because you’re trying to see if the tip of the auger is turning, located way in the back of the burn pot.

Any help would be most appreciated. Thanks.

I don't think you can easily see from the front when the fire is going. Maybe if you had a WIFI camera mounted where it could see the auger shaft/gearbox/motor shaft turning. Like you say, if the motor shaft is turning, the auger will be turning. Another method might be to have a wifi or BT current probe on a motor lead, and determine normal current verses stalled.

 

[Whitenuckler]

You could also wire in an AC ammeter direct read (no CT) as the current is small if I remember.

 

[NS P-68]

With your stove empty place a white mark on the end of your auger. You would have a 4rpm motor....it should take one minute for that white mark to make one revolution. Put the stove in test and shine a light through your glass and time your auger. If its slower than that under no load, it will probably be significantly slower with a hopper full of pellets

 

[Ssyko]

1min makes 4 revolutions😎

 

[Ranckie]

My apologies for the late response; I had to be away for a bit. I like all of the ideas put forth so far, and I actually thought about putting a Wi-Fi camera behind the stove since I already have Blink cameras, but I don’t think I have enough room behind the stove and here’s why; I forgot to mention in my original post that I don’t have an insert in a conventional brick and mortar fireplace, rather I used a ‘can’, or metal enclosure made by Harmon that is inserted in a false chimney chase that I built. You can see it in the attached photo’s showing the metal enclosure during construction, and after the project was completed. I built all of what you see including the bookcases, and the only item I purchased was the mantle because I was able to buy one at Mantles Direct for less money than it would have cost me to build one.

I like the idea of measuring the current and have a clamp type amp meter and could run a wire outside the stove looped in series with one of the motor leads. I also like the idea of marking the end of the auger with white paint but the problem with that is, it would have to be done while the stove has been running and then shut down because the low fire usually happens after the stove has been running and is hot and at that point, everything is till very hot and still burning. That means that I’d have to let it cool down and then restart it after marking the auger but by then, it would be a cold startup, and everything would be fine until everything gets hot again and I’d be trying the see the auger through a hot, high fire.

I think for now I’ll try changing the control board because it’s the next easiest thing to do. If after that it still does the same thing, it would almost certainly point to the auger binding after the stove gets hot. The last time that happened to me was because the metal spiral band on the original auger was only welded in one spot on the auger core, and I believe that allowed the metal spiral to expand or unwind slightly when hot, thus causing a bind in the auger tube. All subsequent augers had welds in three spots along the auger rod. BTW, I just learned that that metal spiral band on the auger, (on any auger), that part that moves the pellets through the auger tube is called a “flight, or flighting”. We learn something every day.

Thanks to all who contributed responses.

 

[Whitenuckler]

My apologies for the late response; I had to be away for a bit. I like all of the ideas put forth so far, and I actually thought about putting a Wi-Fi camera behind the stove since I already have Blink cameras, but I don’t think I have enough room behind the stove and here’s why; I forgot to mention in my original post that I don’t have an insert in a conventional brick and mortar fireplace, rather I used a ‘can’, or metal enclosure made by Harmon that is inserted in a false chimney chase that I built. You can see it in the attached photo’s showing the metal enclosure during construction, and after the project was completed. I built all of what you see including the bookcases, and the only item I purchased was the mantle because I was able to buy one at Mantles Direct for less money than it would have cost me to build one.

I like the idea of measuring the current and have a clamp type amp meter and could run a wire outside the stove looped in series with one of the motor leads. I also like the idea of marking the end of the auger with white paint but the problem with that is, it would have to be done while the stove has been running and then shut down because the low fire usually happens after the stove has been running and is hot and at that point, everything is till very hot and still burning. That means that I’d have to let it cool down and then restart it after marking the auger but by then, it would be a cold startup, and everything would be fine until everything gets hot again and I’d be trying the see the auger through a hot, high fire.

I think for now I’ll try changing the control board because it’s the next easiest thing to do. If after that it still does the same thing, it would almost certainly point to the auger binding after the stove gets hot. The last time that happened to me was because the metal spiral band on the original auger was only welded in one spot on the auger core, and I believe that allowed the metal spiral to expand or unwind slightly when hot, thus causing a bind in the auger tube. All subsequent augers had welds in three spots along the auger rod. BTW, I just learned that that metal spiral band on the auger, (on any auger), that part that moves the pellets through the auger tube is called a “flight, or flighting”. We learn something every day.

Thanks to all who contributed responses.

Beautiful livingroom - reminds me of my last house. I had a gas fireplace there and the whole wall was either mantle and lower cabinets and upper shelves almost ceiling height. Had shutters too but could not open them due to the couch. The auger motors are really cheaply made. Some only have one sealed bearing. The adjustment at the gear end is wonky, and if it is not adjusted just right it will stall the motor even on the bench.

 

[Whitenuckler]

My apologies for the late response; I had to be away for a bit. I like all of the ideas put forth so far, and I actually thought about putting a Wi-Fi camera behind the stove since I already have Blink cameras, but I don’t think I have enough room behind the stove and here’s why; I forgot to mention in my original post that I don’t have an insert in a conventional brick and mortar fireplace, rather I used a ‘can’, or metal enclosure made by Harmon that is inserted in a false chimney chase that I built. You can see it in the attached photo’s showing the metal enclosure during construction, and after the project was completed. I built all of what you see including the bookcases, and the only item I purchased was the mantle because I was able to buy one at Mantles Direct for less money than it would have cost me to build one.

I like the idea of measuring the current and have a clamp type amp meter and could run a wire outside the stove looped in series with one of the motor leads. I also like the idea of marking the end of the auger with white paint but the problem with that is, it would have to be done while the stove has been running and then shut down because the low fire usually happens after the stove has been running and is hot and at that point, everything is till very hot and still burning. That means that I’d have to let it cool down and then restart it after marking the auger but by then, it would be a cold startup, and everything would be fine until everything gets hot again and I’d be trying the see the auger through a hot, high fire.

I think for now I’ll try changing the control board because it’s the next easiest thing to do. If after that it still does the same thing, it would almost certainly point to the auger binding after the stove gets hot. The last time that happened to me was because the metal spiral band on the original auger was only welded in one spot on the auger core, and I believe that allowed the metal spiral to expand or unwind slightly when hot, thus causing a bind in the auger tube. All subsequent augers had welds in three spots along the auger rod. BTW, I just learned that that metal spiral band on the auger, (on any auger), that part that moves the pellets through the auger tube is called a “flight, or flighting”. We learn something every day.

Thanks to all who contributed responses.

If you make up a #16 or #18 insulated blade "jumper" male female you can dig into your wiring bundle and extend the auger hot when you change the control card. I added extension wires to all my hots from the control card opening. It would probably come out of the control card opening if you don't fully install the card tight. I have a P43 though so I'm sure an insert is different.