Might have solved my P68 burn problems...

[Leafmold]

Hello,
Thought I'd share some observations of burning my P68. Have been reading this forum for quite some time, it's a great site.

Have been burning my self-installed stove since Fall '05. Stove has been running lousy for quite a while and I was blaming it on a bad batch and/or mildly damp batch of Juniata pellets, they're stored outside and covered well.
Stove bought 10/05. Serial# 003...built in '03?
Stove heats 1200 sq. ft. 1910, very drafty Colonial. Existing exhaust setup is 2' horizontal pipe through wall to a square-end type termination cap. Combustion fan low burn adjustment setting is maxed out.

Stove ran very well for approx. 2 1/2 seasons with no problems at all. Decided to install an OAK last Winter, during a very windy weekend. Realized smoke in hopper, called dealer, his very first question was "why did you install an oak".
He explained that oak could be causing my problem, in concert with the wind racing into oak and/or exhaust pipe. So I disconnected oak, and still had hopper smoke.
Smoke with oak installed and uninstalled.
Smoke with heavy wind outside and with no wind outside.....ok...

Was scraping burn pot many times a day to control the buildup of hopper smoke. Besides hopper smoke, stove was producing consistently lazy flames, creosote around burn pot area - with an occasional flame on the outside of burn pot, and a consistently-timed auger banging. The last flame witnessed on outside of burn pot was accompanied by the flame guide being pushed up by incoming pellet feed.

The more I read this forum, the more I figured I was the proud owner of a 'Sticky Stove'.

While cleaning stove, discovered two 'air ports' located in burn pot just above auger tube, one on the left and one on the right, about the diameter of a pencil or a bit smaller. First I fashioned a heavy paper clip, then a short length of coat hanger, each filed to a sharp point, and probed these ports. They were both clogged up tight with burned and unburned pellet material.
All this time, never knew these air ports even existed. Have read a million times in this forum about "burn pot holes", but to me, these ports are different - have never heard about these on this site. Always figured the burn pot holes spoken about were the many holes in multiple rows in the burn pot.

After clearing out these ports, there is no more lazy flame and no more hopper smoke. Oak is installed. Will have to monitor creosote situation when burning on low, but right now there is none. Stove runs very well now, now that it can breathe.
I'm thinking that the installation of oak, smoke in hopper, and clogged air ports were all coincidence.

- Also removed the auger slide plate and cleaned up the tar/crud on the bottom of it. I think the auger banging was probably caused by excessive fines in auger tube, and /or the crud on the bottom of slide plate catching on the plate / housing below it. I'll now burn a bag or two at a time till near empty, instead of dumping in bag after bag. Might help the fines-induced auger banging.

Just for giggles, once the weather warms up, I'll install the parts I just picked up for a 3' exterior vertical rise. Figure it can only help the situation, not hurt it.
I may simply still have a 'sticky stove' and will continue to monitor it, but my fingers are crossed that these particular air-starved problems were solved by cleaning these air ports, and will make sure they stay clog free.

 

[TomPajak]

holy crap..I JUST found these 2 ports myself while cleaning..
had a pellets chunk jammed in each 1...
now my stove is running fantastic..either because of these 2 getting unclogged I hope..or the new pellets I've NEVER used b4...but yea..
as for your 2in piping I thought 3in was the minimum

ALL P68 owners out there..CHECK THOSE 2 AIRHOLES OUT

 

[bungalobob]

Just curious, and please forgive my dirty burnpot. After shut down this morning and reading your post, I did quick scrape just to see if these are the two holes you speak of. These holes have been mentioned in some previous posts, but never a picture posted with them, and I have always assumed that these are the ones that are being spoke of, are they? Hope there are not two more holes being elusive in the burnpot.

 

[newf lover]

I was wondering the same thing. They don't appear to lead anywhere. I've noticed the same thing on mine, but haven't paid much attention. I thought it was for a resting place for the flame guide.

 

[TomPajak]

other posts say these are airholes...and yes those are the ones...

 

[bungalobob]

other posts say these are airholes...and yes those are the ones...

Well, I ran a thin wire down them to make sure they were not dead-ended and it went a couple of inches into what felt like open space, probably the same chamber that contains the ignitor. Mine have never appeared plugged during any of my cleanings. I guess they are air holes because there are matching recesses on the under side of the plate that goes over burnpot. You would think that if they are important that Harman would at least mention them in their 'Burn Pot Maintenance section of their instructional manual. That is one very poor manual to say the least, but that has been brought up on many other posts. I guess if they give to much info, their consumers will never call the dealers for service. Well, at least we have this forum for useful information (sometimes).

 

[Leafmold]

Yes, those are the air ports I spoke of. Thanks for adding your photo.
These two ports lead to the belly of burn pot, verified with a mirror. Mine probably got plugged up from being too aggressive with burn pot scraping, over time. Now that I know what can happen when these get plugged up, I'll go easy with a sharp chisel instead of the tool provided with stove.
Yea, the matching recess in flame guide was the giveaway for me.
Also, these ports seem fairly deep, make sure they're completely free from debris. This procedure will now be included in every cleaning this stove gets. What a difference it makes.
Yea, Harman left this tidbit out of their manual for a reason!

 

[Lousyweather]

there are several iterations of the feeder mechanism......Im gonna attach the most common type here, an actual feeder body from a p68....note the absence of any holes? Those two holes end at a gasket which deadends into steel......in other words, those holes dont go anywhere, at least on my feeders.......see the pics....the round tube is where the end of the auger sticks out, and the four bolts go thru the stove body, and the burnpot bolts on them......

 

[Leafmold]

There have been design changes in the new stoves, so I am told. Specifically, direct vent/tube vent from hopper to auger tube. And an extra row of Burn Pot Holes in bottom of burn pot close to auger tube. My stove has neither. Those are redesigned assemblies.
Dealer who sold me the stove told me about the two service tech. bulletins regarding modifications for hopper smoke and carbon build up.
Talked to a second dealer who had never heard of the second bulletin.
These dealers are good and know their stoves, but with all their questions about my setup and did I try this and it could be that, they never asked me if I had checked out these air ports. Makes me wonder if they even know about them. Guess they'd rather throw parts and my cash at it...many business' work the same way.
I'm not a stove guy, that's not my business. But this is a very simple thing to check if you are burning poorly, with hopper smoke issues...and I figured it out without the help of TWO separate dealers...feel 40 lbs lighter with this stress off my shoulders.
These ports aren't just "holes", they appear to be tubes, as in a chase.

 

[Lousyweather]

There have been design changes in the new stoves, so I am told. Specifically, direct vent/tube vent from hopper to auger tube. And an extra row of Burn Pot Holes in bottom of burn pot close to auger tube. My stove has neither. Those are redesigned assemblies.
Dealer who sold me the stove told me about the two service tech. bulletins regarding modifications for hopper smoke and carbon build up.
Talked to a second dealer who had never heard of the second bulletin.
These dealers are good and know their stoves, but with all their questions about my setup and did I try this and it could be that, they never asked me if I had checked out these air ports. Makes me wonder if they even know about them. Guess they'd rather throw parts and my cash at it...many business' work the same way.
I'm not a stove guy, that's not my business. But this is a very simple thing to check if you are burning poorly, with hopper smoke issues...and I figured it out without the help of TWO separate dealers...feel 40 lbs lighter with this stress off my shoulders.
These ports aren't just "holes", they appear to be tubes, as in a chase.

The two pictures shown above are feeder assemblies that are roughly a month old. The two feeder assemblies shown ARE the "modified" design as well (the new hole made to get air to the rear of the auger isnt shown in these pictures). Your 2005-era unit didnt have the lower burn pot holes, nor do the "tubes" go anywhere or do anything. Tech Bulletins come out when a stove has gone out as off-spec or possibly defective.....I dont think there are any official "tech bulletins" pertaining to the "sticky stove" syndrome. Most likely your unit is burning better because of the better-than-average cleaning that you accomplished as of late. More people should do what you did (do a thorough job of cleaning their stove). If it makes you feel better thinking you fixed it though, more power to ya!

 

[TomPajak]

so what does the newer assembly fix?

 

[Lousyweather]

it introduces air to the rear of the auger, supposed to help with the "sticky stove" issue. Its too early to tell if it works...personally, I think the hole is too small and will clog up, but I didnt design the thing. It kinda does the same thing as another fix we've been doing for about 2 years. Your cant see the hole on an existing stove without pulling out the auger.

 

[krooser]

Use a leafblower after every ton and those ports will stay squeaky clean... dirty stoves aren't happy stoves.

 

[bungalobob]

there are several iterations of the feeder mechanism......Im gonna attach the most common type here, an actual feeder body from a p68....note the absence of any holes? Those two holes end at a gasket which deadends into steel......in other words, those holes dont go anywhere, at least on my feeders.......see the pics....the round tube is where the end of the auger sticks out, and the four bolts go thru the stove body, and the burnpot bolts on them......

I don't have time right now to check, but the holes I checked ran down the back of burnpot, not through the plate that you have pictured. I'm going to find out for myself later on, have to get go to work. What I will do to satisfy my own curiosity is run the thin wire down the holes and pull out through ignitor clean-out hole if possible. Since you have a feeder assembly laying around, do you have access to a burner pot assembly?

 

[Lousyweather]

of course I do, Bob. Im thinking that fine wire youre pushing down is just going in between the burnpot and the stove body (where the gasket is)

 

[wwburning]

I have a P61a-2 and have had a slight amount of smoke in the hopper twice. It happened it seemed when the pellets were real low in the hopper AND the stove needed to be cleaned. It would not happen if the pellets were low and the stove was clean. After cleaning out the burn pot and under the burn pot (where the plate is held in by the two screws is) the stove ran much better and the smoke in the hopper vanished on the fire up after cleaning the stove..... just my thoughts...

 

[Leafmold]

Most likely your unit is burning better because of the better-than-average cleaning that you accomplished as of late. More people should do what you did (do a thorough job of cleaning their stove). If it makes you feel better thinking you fixed it though, more power to ya!

These two air ports on either side of auger tube are a design of the burn pot, not feeder assembly. They travel down vertically, into the belly of burn pot. Your probe, when inserted all the way down into these ports, will be seen with a mirror and a good light, deep inside burn pot.
They provide air from the inside of burn pot (belly) to fire area of burn pot, right at the back wall of burn pot, directly above the auger, as per their location. Plug these ports and run stove for a while, and tell me what happens. Smoke in hopper? Lousy flame? Smokey exhaust? 1/2" thick clinkers on the flame guide surface as hard as stone? (left that one out in initial post.)
Regarding these tech. bulletins, they have been discussed in detail on this forum which can be found in a search.
1) tube vent from hopper to auger tube, to address hopper smoke.
2) an extra row of Burn Pot Holes in bottom of burn pot close to auger tube, to address hopper smoke.
Apparently, the new designs address these two service modifications.

I had a serious problem. Hopper full of thick smoke, on an every day basis.
Cleaned these plugged-up-tight ports - no more problem.
I have zero smoke in the hopper now.
I haven't seen a new p68. Have you seen one built in '03? Look at the flame guide. It has a matching recess for these two ports.

 

[Lousyweather]

Ive seen new P68's, old P68's, mid-term P68's. Ive seen very few gummy P68's. I think youre going to get to know your P68 much more intimately when yours gums up.

 

[Leafmold]

Ive seen new P68’s, old P68’s, mid-term P68’s. Ive seen very few gummy P68’s. I think youre going to get to know your P68 much more intimately when yours gums up.

So, if you have seen very few gummy P68's, why is mine going to gum up? Please explain this.

You are a dealer, correct?

 

[Lousyweather]

Ive seen new P68’s, old P68’s, mid-term P68’s. Ive seen very few gummy P68’s. I think youre going to get to know your P68 much more intimately when yours gums up.

So, if you have seen very few gummy P68's, why is mine going to gum up? Please explain this.

You are a dealer, correct?

as per your reference on this site to the "tech bulletins", there are also many references to the sticky stoves here....do a bit of a search, you'll find them.

 

[freebird77]

I just cleaned my P61 yesterday, and never thought to look to see if I have them. I read this post earlier, and still forgot to look. Does anyone know if the P61 has them? Mine has been rebuilt because of hopper smoke, with new feeder assembly, burn pot, auger tube and auger and hopper.

 

[freebird77]

Also, for the amount of money these things cost, youd think you would get a manual with a bit more information. The one I have with my stovepretty much sucks. Ive learned way more on this forum then Id ever get out of that lame manual. Thanks everyone.

 

[capecod]

First year/burning season with P68. During weekly cleaning, I checked for these two holes and found them. Both didn't seem like holes, because they were "blocked" with a tan substance, which I assumed to be perfectly lodged pellets. i "poked" a little with a wire, nothing happened. Didn't want to probe further, for fear of damage. As I said, first year with stove, first burning season, flame seems as strong as ever. But, are these pellets blocking air? Any advice?
Thanks,
Marina

 

[TomPajak]

yup..them tan things are pellets jammed in there..thats what mine looked like,,but as I tried to clean it ,the wire only could get maybe 1/2-3/4 inches down in so Im thinking they're still plugged????????
anyone??

 

[Leafmold]

I do not have a new stove. Bought in '05. Built in '03?
My stove has these air ports. Yours might not. The newer burn pots might not. I haven't seen a new burn pot. If it looks like a port/tube/chase, and not a gasketed joint, then check it out. My burn pot looks identical to the one in Bob's photo. If it looks like Pellet Material ( burned and/or unburned) is jammed in there, keep probing until these ports are completely clear. Probe deep enough to clear any jam. That's what I did. These ports seem to be the diameter of a sipping straw. Picture a pellet chunk jammed down tight into a sipping straw. Might have to CHIP IT OUT. ie: a sharp probe. My right port took me 2 HOURS to clear. It was a nightmare to do. Not easy. But it's clear now and the stove purrs.... no more smoke in hopper - what a concept!
Hope this helps.