Harman p61A flutter flame/woofing issue

[Micmann]

After years of flutter and now some pretty serious backburn or hopper smoke (videoed above) I decided it was time to do something to see if I can rid the stove of these issues. I thought i would try the intake bypass that others have done and that the new stoves now come with. The P61 is not known for backburn/hopper smoke, but mine has done it in the past on rare occasions and has started this season with an apparent problem. I hope hope hope the backburn remedy also takes care of the flutter.

I feel the flutter and backburn are a brother/sister issue. I have no proof, but i just feel they are related somehow since the times I have had smoke in the hopper have also been when the flutter is at it's worst. The following pictures and video are what I have done hoping in all hopes that it resolves this issue. As I write this the task has been completed and I'm waiting for all silicone seals to dry before starting the stove. So the outcome will not be known for a little while with some burn time, but i will report back with an outcome.

I realize others have posted extensively in various ways on this, but I don't think I have come across a P61 detail unless I have missed it. I also can't remember if any have crossed over the backburn and flutter issue both trying to be remedied by the bypass tube. It's usually either one issue or the other. I must thank those that have posted long before me to give me the insight as to what can be done and what i might find. Thank you!

After removing the feeder unit and soaking it in hot water for about an hour and brushing it here are some before and after pictures of the augur tube. (hint I used one of those big plastic bucket tubs used at cookouts to hold the beer or soda on ice. It was the right size and worked great.)



Here is the finished bypass tube. I used 1/2" OD with 3/8" ID nylon tubing. Harman's kit is silicone tubing that has a higher temp rating. But the Nylon is good up till 175f so it should be good since it is not in use next to any major heat. It sits just out of the way of the feed arm.



Before reinstalling the burn pot and feeder unit I sanded all pieces for a smooth flush fit.


Here is a video of some of what I did. It's not a detail step by step, but has an overview of a few points and hopefully can help the next guy/gal. One note on the video. You will notice I changed the tube location from where I originally state I'm going to put it. My stated location would have put the hole and tube in the main slide for the pellets. After thinking I didn't think this would be a good idea as this area should probably be kept free of obstructions. I accidentally erased some footage that showed this change and how i made it work. I only noticed the missing footage after everything was complete. Doh!

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Here is the link to another option with drilling a direct air port into the tube. The same principle can be done on the P61. https://www.hearth.com/talk/threads/harman-accentra-gummy-stove-syndrome-solution.45548/#post-906607

Like I said it's all back together nice and pretty waiting for the seals to dry. We're heading into a few warm days again so it may take a week or so, but I'll let you know what transpires.

 

[Micmann]

Update: After the cleaning, intake bypass installation and exhaust blower fan blade replacement I still have not successfully ridden the stove of the flutter flame. It does not seem to be as severe as before, but is still present mostly when the feed door is open as previously. I have only burned a few bags so this is not an exhaustive test, but an initial one. I will report back down the road when I've had the chance to burn some steady and different brands of fuel.

Also the back back burn/hopper smoke issue seems ok at this point, but i need more time to assess as i did not have this but a few times a year. I will post down the road if I notice it happens again.

Lastly i do have a concern about the bypass. I know it's on the new stoves, many have installed it and doesn't seem to be an issue, but what stops the pellets from burning all the way back, following the new air supply, into the feed chamber on low burn? Before the bypass the augur tube was void of an air supply and stopped pellets burning back to far. I have tested a low burn and shut down and it seems to be alright, but i do notice that the pellets burn into the augur tube on a shutdown further than they used to. On a low burn with the new augur air supply the pellets burn further back in the burn pot and closer to the augur. This change on low burn and shutdown may lead to a dirtier augur tube and needed removal and cleaning. Time will tell. Cleaning is ok, a fire in the feed chamber then hopper would be bad.

Hope this helps somebody.

I'm still looking for what causes the flutter and how to stop it if anybody comes across anything or has insights.