Why does my stove sound like a subwoofer? Low frequency vibes... Help!

[lbcynya]

I know you said it does it with OAK on or off, but I'm putting this out there anyways... I installed the OAK on my P43 last night, I used 3" sheet metal duct, like furnace duct but smaller (Home Depot OAK for $8, better than $100+). The duct I picked up was in 2 pieces, one was 3ft long, the other was an adjustable angled piece that was only 12".

I installed it with the stove running. I put the 12" piece at the stove side of things and as soon as I did that I noticed the same symptom you described. I connected the longer piece that goes through the wall, and it stopped... took it off again, it started. It only happened with that 12" piece attached to the back of the stove, still taking air from inside the house, but just 12" further away from the stove. Strange.

The hopper was nearly empty, so I filled it and tried it again... no fluttering with OAK on or off, or the 12" piece on or off. Consistent.

This 12" piece I'm talking about is an adjustable elbow, so the air going through it gets diverted a bit and probably creates some wicked air turbulence going into the combustion chamber. The extra air volume in the nearly empty hopper probably amplifies it. Just a theory, I dunno.

So that's what I have observed, I don't have any solution but hopefully the extra observation helps with a diagnosis.

Is there any way you can change an angle or a length in your OAK to see if that quietens it? I assume you probably don't run it with the OAK off anyways.

Coincidentally, I also get the faint whistle sound on initial flame as mepellet described, but it's barely there and goes away rather quickly. I haven't tried to see if it does this with the OAK also, but it does do it with a full hopper.

Very interesting observation indeed

Yes, mine does it with/without the OAK, but I haven't tried no OAK with a window open to reduce the basement pressure. Will try that.

I also used 2 completely different OAK systems with no change in vibes. 3" PVC the installer put in the wall (now decommissioned) and my current setup which is Selkirk DT which uses the 6-5/8" pipe for fresh air. Also, the fresh air is heated by the exhaust air, so I figured that would slow it down a bit. Nope.

I'm wondering if what you experienced wasn't turbulence, but greater incoming velocity of air... That doesn't explain why it doesn't happen with a full hopper nor at low or high flame.. You'd think it would be worse at low flame. My low flame doesn't seem "over fed" nor does my large flame seem starved for air.

Remember, I say all of this with 50% of my air inlet blocked off. Turns into a blast furnace with the restriction removed...

 

[Lineman30]

Did some more observing this morning and really noticed that it doesn't matter if its full or low there is still a low tone freq and a werid erratic flame. When its full the glass and basically the whole unit vibrates with the flame very erratic. You can really feel it on the door handle. When its less than a full hopper that's when the low tones are noticeable and when its really low to empty its very noticeable. Its almost at times its starving for air. The flame shrinks allot at a erratic rate then it will come back to normal. I was just playing around and released the tension on the front door slightly and its running a little better.

 

[LIpelletpig]

This is a common problem with the Accentra Insert as well. A year or two ago I experienced the same issue and I had just installed an OAK. Removed the OAK and the problem went away. I am betting this is an OAK issue and you need to find the sweat spot. It's interesting though that it's effecting your unit and it's not an Accentra.

 

[Lineman30]

This is a common problem with the Accentra Insert as well. A year or two ago I experienced the same issue and I had just installed an OAK. Removed the OAK and the problem went away. I am betting this is an OAK issue and you need to find the sweat spot. It's interesting though that it's effecting your unit and it's not an Accentra.

Well, actually my unit is an Accentra. I've pulled the OAK off and its the same effect. I even put my ear up to the inlet and can hear it muffling. Was thinking maybe there is a fluctuation of voltage to the combustion motor causing it to do it. Or could it be an ESP probe??

 

[PJPellet]

Just wondering how you are making out with this. My Harman P43 is doing it too. Drives me nuts. I didn't notice this in the Spring, but I wasn't able to be around the stove back then either. I notice when I crack the door that you can feel the door pulsate in your hand to the fluttering. Would love to fix this as it's the only issue driving me nuts. Does the hopper level really seem to affect this? Mine seems to do it at every hopper level.

 

[Lineman30]

Just wondering how you are making out with this. My Harman P43 is doing it too. Drives me nuts. I didn't notice this in the Spring, but I wasn't able to be around the stove back then either. I notice when I crack the door that you can feel the door pulsate in your hand to the fluttering. Would love to fix this as it's the only issue driving me nuts. Does the hopper level really seem to affect this? Mine seems to do it at every hopper level.

Still having the same issues. Really doesnt matter how full or low the hopper is. The fuller it is the more quite it is though. Also, when i crack or touch the door handle you can feel it pulsate. The pellets even jump around like pop corn in the pot during this. To me, it has to be a difference in air movement though the pot. I've noticed some times when the auger is turning it goes away and also as its turning or done with the cycle it stops. Could it be how the auger is postioned during and after each cycle causing it to do it? I'm as clueless as anyone else but it has to be a difference it air movement/air pressure...

 

[tundraSQ]

Is the stove out of balance on the feet? I had a similar noise when i first installed my stove, and i found that i could make it go away by leaning on the top of the stove in one corner...so i fussed with the leveling feet and it went away.

 

[lbcynya]

Just wondering how you are making out with this. My Harman P43 is doing it too. Drives me nuts. I didn't notice this in the Spring, but I wasn't able to be around the stove back then either. I notice when I crack the door that you can feel the door pulsate in your hand to the fluttering. Would love to fix this as it's the only issue driving me nuts. Does the hopper level really seem to affect this? Mine seems to do it at every hopper level.

No, not yet. Some of the things I've tried have yielded no difference. Hopper level seemed to help at first, but that too is not as beneficial as I'd hoped. I did discover that I have a gasket leak on the door main door/ash pan door (it a 2n1 on the xxv), so we'll see if that changes anything. Found it by pulling the plug to simulate a power outage. Smoke was seeping out towards the bottom of the door. That area is really hard to see, so I'll have to do a little trial and error.

 

[lbcynya]

Is the stove out of balance on the feet? I had a similar noise when i first installed my stove, and i found that i could make it go away by leaning on the top of the stove in one corner...so i fussed with the leveling feet and it went away.

Hmmmmm. Will try that too. Thanks!

 

[PJPellet]

Is the stove out of balance on the feet? I had a similar noise when i first installed my stove, and i found that i could make it go away by leaning on the top of the stove in one corner...so i fussed with the leveling feet and it went away.

Hmmmmm. Will try that too. Thanks!

Cool, I'll try that too. I'm gonna keep trying things til I get it figured out. I notice when I open the hopper that it goes away too. Seems to be a common Harman thing.

 

[tonyd]

I also had a woofing problem with my Accentra and had the intake blocked off. After cleaning the stove outside, I fired it up and noticed the stove was woofing. When taking the stove outside I removed the hopper top and lid assembly 4 3/8 bolts to reduce weight. When I fired up the stove, it was woofing and I noticed the hopper seal was sticking out and wasn:t aligned properly. I pulled the top off, resealed the hopper gasket making sure all butt joints were tight and bolted the top back on. Woofing was gone . Removed the tape from the intake ,woofing gone. After unbolting the hopper lid while the stove was running I would lift the top to break the seal and the stove would start woofing. They say there are no coincidences. It did work for me .Hope this helps.

 

[stoveguy2esw]

its an air issue, if you watch the fire it "quakes' when this is happening as well. ive seen our stoves do it too. sometimes you can make it go away by putting a "speed bump" in your intake. try this

cover the intake pipe on the stove by about 1/4 of opening just use a piece of silver tape, leaving 3/4 uncovered. do this whille teh stove is rumbling. see if it goes away or get to be lesser frequent in happening.if gone, great leave the tape there and reinstall oak back over it, if its lessened but not gone reposition tape to cover slightly more unntil you make it go away and still burn clean. with an ESW unit usually when they do this covering somewhere between a quarter and a third of the intake makes it go away. you do not want to cover too much as it will make you burn dirty but usually there is a "sweet spot"

that said i do not know if this will"fix" this on a harman. but its easy to try and can be removed instantly. hope this helps ya

 

[PJPellet]

its an air issue, if you watch the fire it "quakes' when this is happening as well. ive seen our stoves do it too. sometimes you can make it go away by putting a "speed bump" in your intake. try this

cover the intake pipe on the stove by about 1/4 of opening just use a piece of silver tape, leaving 3/4 uncovered. do this whille teh stove is rumbling. see if it goes away or get to be lesser frequent in happening.if gone, great leave the tape there and reinstall oak back over it, if its lessened but not gone reposition tape to cover slightly more unntil you make it go away and still burn clean. with an ESW unit usually when they do this covering somewhere between a quarter and a third of the intake makes it go away. you do not want to cover too much as it will make you burn dirty but usually there is a "sweet spot"

that said i do not know if this will"fix" this on a harman. but its easy to try and can be removed instantly. hope this helps ya

Great, I will try this today too as I need to clean the pellet stove today. Thanks!

 

[Lineman30]

I also had a woofing problem with my Accentra and had the intake blocked off. After cleaning the stove outside, I fired it up and noticed the stove was woofing. When taking the stove outside I removed the hopper top and lid assembly 4 3/8 bolts to reduce weight. When I fired up the stove, it was woofing and I noticed the hopper seal was sticking out and wasn:t aligned properly. I pulled the top off, resealed the hopper gasket making sure all butt joints were tight and bolted the top back on. Woofing was gone . Removed the tape from the intake ,woofing gone. After unbolting the hopper lid while the stove was running I would lift the top to break the seal and the stove would start woofing. They say there are no coincidences. It did work for me .Hope this helps.

Was your woofing causing you flame to be erratic and making you pellets and ash to jump around in the pot?

 

[Lousyweather]

humor me here.......pull off the flame guide, and run the stove.....does it go away? DONT run the stove for any long perior of time without the flame guide, but try it, let us know what happens........

 

[tonyd]

I put a crossover tube on mine and the tube cured the fluttering and erratic flame. and smoke in the hopper.

 

[Lineman30]

[quote=tonyd]I put a crossover tube on mine and the tube cured the fluttering and erratic flame. and smoke in the hopper.[/quote]

I also did, but only cured the smoke in the hopper... I was hoping for a complete cure

 

[flynfrfun]

Just throwing something else out there....is it possible the OAK intake flapper is "flapping" which sets up the resonate whoofing? It's possible it is just the wrong weight so that it opens and closes constantly (like a tractor exhaust pipe flapper) instead of opening and staying open. I like the idea of putting some metal foil partially over the intake...sound like you just need to slightly disturb the intake air to get out of the resonant frequency thing going on.

 

[SmokeyTheBear]

It is just like tuning a pipe organ.

Anything and I do mean anything in the air path (both air paths) can set up the noise or change it.

 

[PJPellet]

Well I tried the leveling idea and no difference. I blocked off different portions of the OAK and no difference. I already have the crossover tube as my stove is newer and came with one. There is one more thing I am going to try tonight.

Went to my dealer's showroom today and some of his stoves were doing it! I talked to him about it and he said that he has seen some do it and others don't do it. He says it's not abnormal or normal. I said it's irritating! He's a good dealer and I trust him, I think he knows I am a bit crazy with the pellet stove though. Things that don't bother most people bother me.

I am now going to loosen the set screw on the combustion blower impeller and move it in small increments and see if that does anything. I will post back my results.

 

[ARGlock]

I have a Quadrafire and if after cleaning I don't align the baffle incorrectly, I get that type of low frequency vibration. Typically it happens when I've left more of a gap on one side of the baffle that the other side of stove. Not sure if this makes sense if you have a Harman or other brand.

I just cleaned my 4 inch 21 ft. vent with a leaf blower and then started my insert. I experienced that sub woofer sound but I think that's normal with a clean vent. It sure makes a difference with the flame Nice blow torch quick flame!!


Stay Warm,

AR

 

[lbcynya]

Just throwing something else out there....is it possible the OAK intake flapper is "flapping" which sets up the resonate whoofing? It's possible it is just the wrong weight so that it opens and closes constantly (like a tractor exhaust pipe flapper) instead of opening and staying open. I like the idea of putting some metal foil partially over the intake...sound like you just need to slightly disturb the intake air to get out of the resonant frequency thing going on.

Logical, but, no it doesn't flap. Sat on the ground with my hand around the back of the stove and in contact with the flapper while the flame "quaked" and the stove woofed.

I will say that running the stove with the stat does make a difference because it's on high/low and little in between. Most of the woofing occurs at mid flame. So stove temp, medium setting is the worst. Right now, for me, what I have is tolerable.

 

[Honda]

I have a p61-A. noticing the same rumbling at mid flame, and the flutter flame. Can hear it at the other end of house while in the shower, always think there is someone in the yard in a truck. Only noticed on low to mid flame. Makes no difference if hopper is full or empty. Would be interested to see if someone finds a fix.

 

[PJPellet]

Just an update as I have been trying to find a fix for this problem. I adjusted the impeller to different positions on the shaft with no change. At this point I am trying everything. This past weekend I did the weekly cleaning and it has been doing it terribly worse than ever since the cleaning. I played with the OAK and no changes. I think the next area is the ignitor compartment. The problem has REALLY gotten worse after this last cleaning. Now when it flutters there is an actual whistling sound that is in rhythm with the flame. I keep hoping someone discovers something that will fix this.

 

[lbcynya]

Just an update as I have been trying to find a fix for this problem. I adjusted the impeller to different positions on the shaft with no change. At this point I am trying everything. This past weekend I did the weekly cleaning and it has been doing it terribly worse than ever since the cleaning. I played with the OAK and no changes. I think the next area is the ignitor compartment. The problem has REALLY gotten worse after this last cleaning. Now when it flutters there is an actual whistling sound that is in rhythm with the flame. I keep hoping someone discovers something that will fix this.

Man, I feel for you. Since I switched over to a wireless thermostat my burn is either on high or maintenance with little inbetween. It's the inbetween where the woofing starts. So, for me, it's not as much a top priority since the woofing is 99% gone. Pellet consumption seems to be very acceptable.

Contrary to popular belief, NO air gets pulled through the auger tube provided the pellet hopper is air tight. All air comes through the bottom of the burn pot and the 2 little corners at the bottom of the flame guide. These pictures helped solidify that - http://www.stove-parts-unlimited.com/P43_XXV_Advance_Accentra_Insert_Burn_Pot_p/1-10-00675.htm

Only thing I can surmise is a leak somewhere in the hopper or it's a resonance caused at a certain frequency due to a volumetric imbalance between the burn box area and the hopper area. That's why it only happens at certain flame heights. I would ass-u-me that a leak would cause woofing from mid-flame up. The fact that a variety of Harman's do it, makes me hesitant to believe it's a leak.