Harman rumbling, jumping flame

I recently installed a Harman Accentra 52I insert and removed a Jotul wood stove. I'm having issues with my flame jumping, rumbling furiously. Not constantly however. I installed it using my existing 6" stainless flue, thru masonary chimney (about 25 ft) and offset box due to a stone face on fireplace. I was told by my dealer that this was fine. Always had good draw on the Jotul.

My setting are feed rate of just under 4, room temp 2/3, 4- 4.5 temp.

I have an old 200+ year old stone house so it is not very tight. I can feel it drawing air under doors and around windows.

It seems like maybe it's starving for intake air (no OAK installed, told not needed) or the 6" exhaust is drawing out too quickly (if that is possible??) I've burned about a ton of pellets and have not cleaned the exhaust as yet. I do clean the blowers, firebox, etc. every 5 bags.

Any help would be appreciated. I enjoy reading everyones posts.

Thanks for feedback. I will turn down my feed rate tonight.

the liner is not capped. The chimney has a large flag stone on top of brick soldiers, for rain protection. I will look into the multi directional outlet in spring. I will adjust the feed speed for now. ......Thanks!

mepellet said:

Common issue with harman Pellet stoves. To my knowledge, there are no side effects other than slightly annoying.

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Would my wife complaining be considered a side effect?

Well I removed it, cleaned the exhaust etc as well as the inside. Turned the feed speed down and it's a little better or maybe it's my wishful thinking. I did tighten my jack bolts as they had come loose. At least it's a little quieter.

I did not check my hi- lo drafts when I installed, as the dealer said it would not be necessary. Is that something I should look into doing to correct my issues and how is it done??