I hope someone on here can steer me in the right direction. Unit is fairly new 4 years maybe 5 tons ran through. This year I have been noticing this said thump as seen/heard in attached video. It was thoroughly cleaned early this season and has only ran maybe 12 bags so far. The operation is fine just this random thump through the cycle. I have watched and there is no rhyme or reason at all when it occurs ie feed or combustion. When the stove is on the down cycle it does not do it only on the ramp up, mid and way down (running in auto mode). Before I start chasing my tail any ideas or suggestions? Really appreciate any and all help!
Harman P35i Insert Pellet Thumping randomly!?
- Thread starter jasonwp
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Whitenuckler
Minister of Fire
My P43 makes some sounds like that. I was told not to worry, it's just the PelletPro gate inside where you clean the fines box. Sometimes it chops pellets in half. There is video on line if you search showing all the moving parts. It's not just the auger.
Fines box? You talking about the metal guard that exposes the auger from the side and a usually a lot of pellets and dust reside after time? I always clean that out during major cleanings. I apologize I looked all over the place online trying to duplicate this sound and found nothing yet. If you have a link id love to see it. Thanks Sir!
My stove was making a thumping sound that was caused by a misalignment of the feed motor chain. Occasionally the chain would ride up on the sprocket and then drop back into place. From the sound in your video clip I don't think that's your cause but I thought I'd mention it anyway.
Whitenuckler
Minister of Fire
I would clean that out during every normal cleaning if possible. On mine I can remove the control card and then it's easy.
Attachments
![[Hearth.com] Harman P35i Insert Pellet Thumping randomly!?](/talk/data/attachments/343/343727-d35f76108999635bd7afbaab17e43fc2.jpg?hash=Hfh0LV7WFg)
![[Hearth.com] Harman P35i Insert Pellet Thumping randomly!?](/talk/data/attachments/343/343728-d57a1453835640194bfac2451c568bbf.jpg?hash=tzH5Om91-a)
Yep that's what I thought you were talking about. I do the same. This year I even put some graphite powder in the auger to aid with dry lubrication.
I heard pellets feeding just before the sound. Most likely a pellet being chopped by the slide plate assembly that is above the fines box. Or sometimes the auger itself will break a pellet that feeds in at a weird angle. (FYI, sometimes a small piece will get caught between the auger and the tube and screech its way down - LOL). (note that the picture is from my P43 so may not exactly match your stove)
![[Hearth.com] Harman P35i Insert Pellet Thumping randomly!?](https://www.hearth.com/talk/attachments/1765614175383-webp.343738/ "[Hearth.com] Harman P35i Insert Pellet Thumping randomly!?")
It is also possible there is some small misalignment of the feeder pusher arm (2.9) and it is thumping back down (never had that happen, so don't really know).
It is also possible there is some small misalignment of the feeder pusher arm (2.9) and it is thumping back down (never had that happen, so don't really know).
ARC
Minister of Fire
Really good video on harman feed system. Another thing to check is that the bolt holding the auger motor to the auger is tight and lined up with the flat half of the motor shaft.
Whitenuckler
Minister of Fire
I initially thought it was just pellet jams, but it will do it while the feed motor is off. It's very sporatic. Going to pull it out today and check everything. My unit is an insert so it's really hard to open things up and run tests.
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Whitenuckler
Minister of Fire
Does it make the sound when it is heating up, cooling down, or when it had been running at the same output, or anytime? Related to the room blower at all? Is it coming from the stove itself for sure, or could be from the back where the liner attaches?
I cranking the sound up and watched again. I heard one loud click sound like metal expanding/contacting.
ARC
Minister of Fire
Sounds like metal on metal to me, almost like the push arm is out of alignment or like I wrote earlier the bolt and motor shaft slipping past the flat half. But then again my hearing aids pick up stuff that they shouldn't. lol
It does sound like metal on metal or metal expansion. It is hard to get video because there is no real pattern. It seems most consistent on the wind up and maybe a few times on the wind down. I just pulled it out and cleaned and blew out the fines box. All bolts were tight and all seemed to look normal.
I just pulled it out and checked all bolts and all seemed good. The only thing I saw was maybe the pellet chute arm, seems like its metal on metal. When I move it manually it clanks but does not sound like the noise im hearing. I really just sounds like metal expansion but its pretty loud and sounds the same all the time.