I hope there are some knowledgeable Harmon pellet stove experts reading this forum these days because I am at my wits end as to solving my problem. I’ll try to be as brief as I can while still giving enough information to those able to help me with my issue.
My stove is a Harmon Accentra Insert, s/n 012615, and was installed in 2007 during a wood stove change-over. I don’t have a fireplace so the stove was installed in what is called a “mounting shell”, that is nothing more than a zero-clearance metal enclosure that the stove slides into. Once completed, it looks like it’s installed in a fireplace. I installed the stove myself strictly following Harmon’s installation procedures, and had the installation inspected and approved by the shop that sold it to me, and also by the local fire inspector. I run my stove on ‘Stove Temp’, and have since day one. I am also the one that has cleaned the stove every fall, and maintained it throughout these seventeen years. Everything I have done was strictly according to the Harmon manual, and with a few minor exceptions, this stove has run flawlessly all these years; (the shop where I bought it attributes it to good maintenance). Over the years I’ve changed out one control board, one igniter, one or two ESP sensors, and an auger feed motor, and that’s it.
For the first 2-3 years I experimented with a few different brands of pellets but finally settled on one brand that has served me well for 14 years, made by Maine Woods Pellets, the largest pellet manufacturer in Maine. It is a blend of hardwood and softwood that I believe consists of 65% soft, and 35% hardwood. Their pellets have been tested and certified to contain less than 1% ash, less than .5% fines, and less than 8% moisture at an independent lab, and contain no additives of any kind. In all those years I have never had any burn issues with their pellets, or the stove . . . . that is until this year.
I burn two tons a year give or take 10 bags or so, and for the last 12 years have purchased them from the same supplier and have always had good luck with them until the pellets I bought last fall. I started noticing “clinkers” in my burn pot, something I had never, ever seen in all those years. I contacted the sales rep from the pellet company and long story short, he said they did have an issue with one batch of pellets, and had other complaints for the same issue, (my guess is, it was most likely sand/dirt embedded in tree bark on a log that missed the de-barker). He readily agreed to swap out my remaining ton, and brought me ten bags of fresh pellets to get me going.
I cleaned out the old pellets and started using the new ones but the stove continued to have issues, burning erratically, until the fire eventually went out by itself. It finally got so bad the stove would not run at all, with the status light finally blinking 6 times, indicating “Incomplete Combustion”. I also noticed that the ash residue was different from years past and now looks like coarse sand or fine gravel, with large mounds of it remaining in the burn pot, piled so high, the incoming pellets can’t move the ashes out, thus killing the fire, (see the pictures I’ve attached).
I finally concluded that the entire exhaust system was most likely plugged and made the dreaded decision to pull the stove out and do a full ‘annual cleaning’; not an easy task for an 81-year-old with two knee replacements who has to pull out an insert that weighs 450 lbs. and get down on hands and knees to brush the tubes. This time, when I got to the cleaning, I saw that stove was the dirtiest I have ever seen it, and mind you, it was thoroughly brushed clean last September. That got me to hoping that because the exhaust was plugged from burning the original bad “clinker” pellets, that I had resolved the issue. Not so. In the three days since that “full clean”, (Feb. 2, 2024) it’s still not burning correctly, with the ‘gravelly’ looking ashes and real low fire, and I’m at a loss as to what the issue is. I know if I continue burning it the way it is, it will just plug the exhaust tubes again and I’ll have to do it all over again.
The things that come to my mind as to what might be causing this are, maybe the door gasket, or the hopper lid gasket is/are leaking, affecting the draft. Both gaskets are the original gaskets and while they look fine, they could be compressed and leaking. I don’t have a draft gauge but can buy one if necessary. Another issue might be, while the control functions of the stove all seem to be working correctly, is it possible that the ESP sensor is bad? My stove has the ESP sensor with the black leads. I know that the dip switches on the control board are set correctly because those were checked by me when I changed out the ESP sensor a while back. When the stove is running, the combustion blower is seemingly working as it should, but the flame doesn’t appear to be a hot as it used to be; like it’s more reddish in color; (draft?).
I apologize for the long explanation but figured I address some of the potential questions that would be forthcoming. Any help and or suggestions would be most appreciated. Thanks in advance.
![[Hearth.com] Harmon Insert Not Burning Correctly](https://www.hearth.com/talk/data/attachments/324/324405-5b3d2e64132e94007d958e94aa5344ed.jpg?hash=z7QFMyeqS2 "[Hearth.com] Harmon Insert Not Burning Correctly")
![[Hearth.com] Harmon Insert Not Burning Correctly](https://www.hearth.com/talk/data/attachments/324/324406-65d504e9db5f252111593911003249db.jpg?hash=Zy-pleKnf9 "[Hearth.com] Harmon Insert Not Burning Correctly")
![[Hearth.com] Harmon Insert Not Burning Correctly](https://www.hearth.com/talk/data/attachments/324/324407-ba5115ae8f2eacb481b414dff6bf7e4a.jpg?hash=QmZLYKa_OC "[Hearth.com] Harmon Insert Not Burning Correctly")
My stove is a Harmon Accentra Insert, s/n 012615, and was installed in 2007 during a wood stove change-over. I don’t have a fireplace so the stove was installed in what is called a “mounting shell”, that is nothing more than a zero-clearance metal enclosure that the stove slides into. Once completed, it looks like it’s installed in a fireplace. I installed the stove myself strictly following Harmon’s installation procedures, and had the installation inspected and approved by the shop that sold it to me, and also by the local fire inspector. I run my stove on ‘Stove Temp’, and have since day one. I am also the one that has cleaned the stove every fall, and maintained it throughout these seventeen years. Everything I have done was strictly according to the Harmon manual, and with a few minor exceptions, this stove has run flawlessly all these years; (the shop where I bought it attributes it to good maintenance). Over the years I’ve changed out one control board, one igniter, one or two ESP sensors, and an auger feed motor, and that’s it.
For the first 2-3 years I experimented with a few different brands of pellets but finally settled on one brand that has served me well for 14 years, made by Maine Woods Pellets, the largest pellet manufacturer in Maine. It is a blend of hardwood and softwood that I believe consists of 65% soft, and 35% hardwood. Their pellets have been tested and certified to contain less than 1% ash, less than .5% fines, and less than 8% moisture at an independent lab, and contain no additives of any kind. In all those years I have never had any burn issues with their pellets, or the stove . . . . that is until this year.
I burn two tons a year give or take 10 bags or so, and for the last 12 years have purchased them from the same supplier and have always had good luck with them until the pellets I bought last fall. I started noticing “clinkers” in my burn pot, something I had never, ever seen in all those years. I contacted the sales rep from the pellet company and long story short, he said they did have an issue with one batch of pellets, and had other complaints for the same issue, (my guess is, it was most likely sand/dirt embedded in tree bark on a log that missed the de-barker). He readily agreed to swap out my remaining ton, and brought me ten bags of fresh pellets to get me going.
I cleaned out the old pellets and started using the new ones but the stove continued to have issues, burning erratically, until the fire eventually went out by itself. It finally got so bad the stove would not run at all, with the status light finally blinking 6 times, indicating “Incomplete Combustion”. I also noticed that the ash residue was different from years past and now looks like coarse sand or fine gravel, with large mounds of it remaining in the burn pot, piled so high, the incoming pellets can’t move the ashes out, thus killing the fire, (see the pictures I’ve attached).
I finally concluded that the entire exhaust system was most likely plugged and made the dreaded decision to pull the stove out and do a full ‘annual cleaning’; not an easy task for an 81-year-old with two knee replacements who has to pull out an insert that weighs 450 lbs. and get down on hands and knees to brush the tubes. This time, when I got to the cleaning, I saw that stove was the dirtiest I have ever seen it, and mind you, it was thoroughly brushed clean last September. That got me to hoping that because the exhaust was plugged from burning the original bad “clinker” pellets, that I had resolved the issue. Not so. In the three days since that “full clean”, (Feb. 2, 2024) it’s still not burning correctly, with the ‘gravelly’ looking ashes and real low fire, and I’m at a loss as to what the issue is. I know if I continue burning it the way it is, it will just plug the exhaust tubes again and I’ll have to do it all over again.
The things that come to my mind as to what might be causing this are, maybe the door gasket, or the hopper lid gasket is/are leaking, affecting the draft. Both gaskets are the original gaskets and while they look fine, they could be compressed and leaking. I don’t have a draft gauge but can buy one if necessary. Another issue might be, while the control functions of the stove all seem to be working correctly, is it possible that the ESP sensor is bad? My stove has the ESP sensor with the black leads. I know that the dip switches on the control board are set correctly because those were checked by me when I changed out the ESP sensor a while back. When the stove is running, the combustion blower is seemingly working as it should, but the flame doesn’t appear to be a hot as it used to be; like it’s more reddish in color; (draft?).
I apologize for the long explanation but figured I address some of the potential questions that would be forthcoming. Any help and or suggestions would be most appreciated. Thanks in advance.
