Hearth.com exclusive! Harman re-designing their burnpot...here's the information

[P38X2]

except any and all of the Harman OAK's (theres only 2) have NO dampers in them at all........

Ahhhh...but he never said it was a Harman OAK

 

[PJPellet]

Pjpellet, just to clarify we're talking about the same flapper/damper piece....you are referring to the metal intake damper incorporated into the stove from the factory, correct? You mentioned you bought a new OAK intake and removed the flapper. I want to be sure you aren't referring to an intake mounted on the outside of the house, not unlike a dryer vent, which also has a similar design but with a reversed flapper.

Yep, I am referring to the metal intake damper incorporated into the stove from the factory, part # 1-10-06810A.

 

[PJPellet]

well, at least you narrowed down the possible "sympathetic oscillation" theory. Sorry if its been stated, but whats the outlet pipe configuration? Have you tried a "minimal installation" configuration with the outlet (straight out, NOT going upwards)? since nearly all of the air going into the stove comes thru the intake damper, it makes sense that the "woofing" would open and close the damper....but, as we now know due to your observations, its a RESULT of the woofing, rather than the CAUSE of the woofing. Since the combustion fan is a constant speed, it is unlikely to be the cause of the woofing. I think I will put my money on the idiosynchracies of variations in the draft caused by variable weather conditions such as piping, barometric pressure differential, and additionally, and to a much lesser extent, cleanliness of the exhaust systen as well. I guess if were a major design flaw, it would be more common than we are seeing, so the only conclusion I can hypothesize is the aforementioned observation above. I know since several folks posting here do mention this "woofing" it might SEEM common, but, given the literally tens of thousands of units produced each year, and the lack of commonality of this issue being pointed out to dealers and service techs, its a very, very small percentage of the stoves produced. How about elevation issues? Has anyone tried replacing the stock combustion fan blades with one of the "high elevation" combustion fans? Just a thought.

Yep I tried a "minimal installation." And I have thought about trying a different combustion fan blade but have not yet. I think I notice things like this more than most people would. Same with my vehicles, I notice every little shimmy, rattle, noise, etc.

The stove sits in the living room where I spend most of my time so I hear every little noise the stove makes. An observation that I have made this season is that the dirtier the stove is the less it does it. The woofing is always worse after I clean the combustion fan blades and the area leading to the esp probe, etc. I have noticed a slight amount of play with the combustion compartment cover(the combustion intake weldment part # 1-10-08516S accessed from behind the ash pan) so I think it is something possibly to do with the play involved here. I really have gone over the stove thoroughly and can rule out most everything else. I only get the woofing when I remove and clean and replace the combustion intake weldment. Once this area gets a couple weeks of ash built up in and around it the woofing all but disappears. I can replicate these results consistently. I used to clean this area weekly but now I clean this area monthly. And I only get the woofing after I clean this area and for about a week or two after then it goes away until the next cleaning of this area. I believe the "seal" between the stove's body and around the combustion intake weldment gets better with stove use because of ash build up, etc. and therefore the woofing stops in my situation. I believe when this area is freshly cleaned that air is being drawn in through it's proper space but also around the weldment where it is not supposed to be drawn in and at this point the woofing begins. Then once this area is sealed up with ash and the air is only being drawn in through it's proper place the woofing stops. As mentioned I can repeat this with the same results so in my case I have figured out what's going on.

I hope I explained that well. I love this P43 and have heated my house for about $425.00 this winter.

 

[P38X2]

I wonder if a VERY thin bead of RTV could be applied on the back of that cover to eliminate the air leak? My older P38's cover fits very snugly and may not fasten after the silicone is applied or if it did fasten, I'd imagine the silicone would fail shortly thereafter due to the fact there simply wouldn't be enough to be structurally sound, for lack of the proper words.

The stove I'm referring to is the one that no longer woofs. No idea how snug the cover is on my new one as I haven't had to clean in there yet but that one woofs a decent amount.