Harman p61A smoke from auger tube

[Honda]

I noticed this problem with what appears to be smoke coming form the auger tube in my 9 yr old Harman P61a recently. here is a short (hopefully) breakdown of what has been going on. Got a new Esp prob last winter, and noticed that now and then it would kick the dist fan off then on when I cleaned the probe while the stove was running. Also, once in a while the probe would seem to read way cooler than it should, and the stove would feed until it maxed out on temp, slack off, then refeed to the max. I would wiggle the wire and would go back to normal. I figued this was no good and got a new probe recently, installed new prob, and now it seems to be running way too cool. On stove temp #5 the flames barely go higher than the flameguide, until the ash builds up. Normally #5 stove temp would be just licking the heat exchangers, and be just where I needed to be in cold weather. Once the ash builds up a bit it burns way hotter, I measure with a IR heat gun at the front centre of stove by heat exchangers. I also notice that until the ash builds up I get a taller lazier flame on one side of burnpot. Replaced ashbin door gasket, glass door gaskets seem fine.

Sooo... To get to the topic of my post, while changing probes I turned stove off, let cool down, then unplugged, fire was not out, but nearly. while I was changing probes, I noticed a small stream of smoke coming up centre between hopper and firebox. looking between the hopper and firebox it appeared to be coming from the auger tube, but I could not tell exactly where.

My question is, has anyone heard of any problems like this before, and is it something that could be patched with high temp caulking until the end of the season. I plan on taking it to my trusty Harman dealer for a complete go over this summer. Also I have noticed a slight whistle noise from time to time on startup, couldn't track it down, but I'm sure this smoke thing is it. And, I have a funny feeling it is the cause of the low flame and low heat output until the ash builds up, and the taller lazier flame on one side of burnpot.

 

[Mr. Spock]

Did I read correctly that you would clean the esp probe while the stove is running?
In relation to other issues it sounds like an air leak somewhere. I am not familiar with your model stove but some easy ones to check are the hopper and door seals using the dollar bill test.

 

[Bioburner]

How old of stove. I have a similar issue but I had to pull the auger and did not reapply silicone on the auger bushing-bearing holder. Since the stove is running pretty much 24-7 have no issue unless ran empty. Yea right, don't see letting it run empty till maybe April. Have a to do list for summer and that is one thing more. May have the first 24 hour period of above 0 today of two weeks.

 

[CJ_starr]

Could be the fines box cover not sealed tightly, that could cause the stove to skip feed cycles. It worries me that you stated that when you turn up the feed rate, the flame is still low. Hope its not the dreaded gummy stove syndrome. Don't see that much with the p-series but I have seen it a few times over the years.

 

[rickwai]

remove all the pellets and make sure there is not something in the bottom of the hopper blocking the pellets from feeding. I have found ink pens, match box cars, christmas decoration, rocks, nails, plastic machine parts ect. That is where i would start. W/ hopper empty you can reach back in on top of slide plate to feel if there is something you cant see.

 

[Honda]

Did I read correctly that you would clean the esp probe while the stove is running?
In relation to other issues it sounds like an air leak somewhere. I am not familiar with your model stove but some easy ones to check are the hopper and door seals using the dollar bill test.

Sometimes if I can't wait for the stove to completely shut down I will just turn off, wait till it cools down, and pull the probe out and wipe it off. I just like to make sure it is clean and reading properly.

 

[Honda]

I've checked all the gaskets, replaced ashbin door gasket and hopper lid gasket. Fines box is good. Something I will try is covering the 5 bottom holes in the burnpot by the auger. I had these covered in the past, but I scraped them out around christmas because I was getting a really tall flame and dirty burn with my old probe that was frigged up and would short out. I don't like at all how the flames come out of augertube on low settings, and i'm a little worried there may be a small hole burned out and that is where the smoke was coming from as stated above.

 

[mikesj]

If I understand you, you have smoke escaping from the stove between the hopper and firebox. That sounds pretty serious to me. I definitely would not be running the stove until I found the leak. Is it possible that the smoke was escaping from the esp hole?

 

[Honda]

If I understand you, you have smoke escaping from the stove between the hopper and firebox. That sounds pretty serious to me. I definitely would not be running the stove until I found the leak. Is it possible that the smoke was escaping from the esp hole?

yes, you are correct. Except the only time I saw smoke was when I unplugged the power to stove when it was nearly shut down. There were a few embers in the burnpot still. I unplugged the power to put the new probe in. When the fans shut off and the embers created a little smoke in firebox is when I noticed the small stream of smoke coming up the centre between firebox and hopper. It never has any smoke while the stove is running. Regardless, there is a hole there somewhere, I couldn't get in to see exactly where it was coming from. I wonder if there is a gasket where the auger tube hooks to the firebox? And, I mentioned hearing the whistle on startup as the pellets first ignite from time to time, and the whistle appears to come from the same area. It is really hard to see in there. I do know it was not coming from esp hole, or fines cover, held a flashlight in to try and track it down, was not coming from either of those. was coming form somewhere on the auger tube.

 

[Bioburner]

Kinda close to what I replied before, could the bearings be going on the auger shaft? Still have no idea how old your stove is!

 

[mikesj]

I've had smoke leak out of my air intake before when I pulled the plug. Before I did anything else, I would pull all the covers off the back and go through a shutdown/startup cycle while I kept an eye on it with a flashlight. Then I would try to re-create the circumstances that lead to the leak to see what I could see.

Good luck with this- I've got the same stove, so I'm pretty curious to see what you find out.

 

[CJ_starr]

They do put sealant around the auger when it gets installed. However, I would think that since the machine mostly operates with negative pressure, if the auger was leaking where it goes into the auger tube it would suck air in instead of blow it out when the combustion blower is on. The older models used just silicone sealant where the hopper connects to the feeder body, may be leaking and causing the whistle noise you hear. There are 2 fiberglass gaskets where the auger tube connects to the firebox. One between the burn pot and the fire box and another between the firebox and the auger tube. Is there any hole burned out at the very opening of the auger tube where the tip of the auger turns?

 

[Lousyweather]

5 hole burnpot, folks! Needs changed out.....the 5 holers can cause erosion of the auger and auger tube, sometimes causing a hole at about 4-7 o'clock in the auger tube, right where it hits the burnpot. I feel this issue is a few things, unfortunately for the owner.
1. 5 hole burnpot should be changed out
2. Bypass tube installed
3. Slide plate check for residue
4. Almost certainly your first joint of pipe where you attatched the stove is leaking...you did use a stove adapter instead of just shoving a joint on, right?
5. If you taped the stove nipple, remove tape, RTV it.
6. erratic operation could be an old circuitboard (pots wearing out)
7. check the upper and lower hopper seals
I'd start there.

If there is a hole at the bottom of the auger tube, air will be pulled thru there and you'll see you pellets burn pretty far back, close to the auger

 

[Lousyweather]

They do put sealant around the auger when it gets installed. However, I would think that since the machine mostly operates with negative pressure, if the auger was leaking where it goes into the auger tube it would suck air in instead of blow it out when the combustion blower is on. The older models used just silicone sealant where the hopper connects to the feeder body, may be leaking and causing the whistle noise you hear. There are 2 fiberglass gaskets where the auger tube connects to the firebox. One between the burn pot and the fire box and another between the firebox and the auger tube. Is there any hole burned out at the very opening of the auger tube where the tip of the auger turns?

not all augers were sealed with silicone (in the rear). Some have none at all.

air would also not be sucked into the auger tube at all if there were a hole there...it would be pulled out.....dont forgett the whole firebox, AND EVERYTHING BEFORE IT, is under negative pressure, so air will be pulled out of the hole, not sucked in. You wont get positive pressure until maybe after the comb fan, and maybe not even then, if the natural draft is strong enough.

 

[CJ_starr]

That's what I said. The machine works on negative pressure. And I also did say that air would be coming into the auger tube from the auger bearing and not blowing out. The only part of the machine that is under positive pressure is from the combustion blower paddle fan going out the vent pipe. And I have seen so many holes in the auger tubes in Harman stoves over the years that did NOT have the 5 holes in the bottom of the burn pot. So I do not believe that the 5 holes is entirely to blame.

 

[ivanhoe]

5 hole burnpot, folks! Needs changed out.....the 5 holers can cause erosion of the auger and auger tube, sometimes causing a hole at about 4-7 o'clock in the auger tube, right where it hits the burnpot. I feel this issue is a few things, unfortunately for the owner.
1. 5 hole burnpot should be changed out
2. Bypass tube installed
3. Slide plate check for residue
4. Almost certainly your first joint of pipe where you attatched the stove is leaking...you did use a stove adapter instead of just shoving a joint on, right?
5. If you taped the stove nipple, remove tape, RTV it.
6. erratic operation could be an old circuitboard (pots wearing out)
7. check the upper and lower hopper seals
I'd start there.

If there is a hole at the bottom of the auger tube, air will be pulled thru there and you'll see you pellets burn pretty far back, close to the auger

what year did the burnpot changed to the better design?

 

[Lousyweather]

what year did the burnpot changed to the better design?

couldnt say exactly, really....other than to vaguely say " a few years ago".....the part number didnt change (I dont think), so would be hard to track.

As for hole in the auger tube and the 5 hole burnpot phenomenon, I dont think Ive seen a holed auger tube in anything but a 5 hole burnpot situation....but, results may vary.

 

[ivanhoe]

thx! i'm looking for a used P61A or P68A at this moment and wanted a heads up on the burnpot changes. so the new design has no airholes near the auger and they start 2" to 3" away? or more?

 

[Lousyweather]

thx! i'm looking for a used P61A or P68A at this moment and wanted a heads up on the burnpot changes. so the new design has no airholes near the auger and they start 2" to 3" away? or more?

right....recent units have no holes adjacent to the auger....about 3" away or so.....

 

[Honda]

5 hole burnpot, folks! Needs changed out.....the 5 holers can cause erosion of the auger and auger tube, sometimes causing a hole at about 4-7 o'clock in the auger tube, right where it hits the burnpot. I feel this issue is a few things, unfortunately for the owner.
1. 5 hole burnpot should be changed out
2. Bypass tube installed
3. Slide plate check for residue
4. Almost certainly your first joint of pipe where you attatched the stove is leaking...you did use a stove adapter instead of just shoving a joint on, right?
5. If you taped the stove nipple, remove tape, RTV it.
6. erratic operation could be an old circuitboard (pots wearing out)
7. check the upper and lower hopper seals
I'd start there.

If there is a hole at the bottom of the auger tube, air will be pulled thru there and you'll see you pellets burn pretty far back, close to the auger

ok, stove is shut down, going to look for a hole by the end of auger. Going to putty the bottom holes in burnpot back up. I had them puttied over all last year and got a better higher burn. Was getting a little smoke earlier this year and tried cleaning them out to see if that helped. Slideplate is fine, clean as a whistle. Stove pipe is good, stove adapter used and all joints are well caulked. dealer lent me a Circuit board to try to rule that out, and my circuit board works same as his. Upper hopper seal is brand new, and all the joints butt up to each other good.

Lower hopper seal, I have no idea, can it be accessed without taking hopper off?

I am suspect of hole in auger tube, or burnpot gasket, or lower hopper seal.

Stove is 9 yrs old to answer an earlier question. new comb motor last year.

 

[Honda]

Kinda close to what I replied before, could the bearings be going on the auger shaft? Still have no idea how old your stove is!

stove is on it's 9th winter. I wondered about bearings, there is a little side to side play in the front of the auger, but no more than I remember there being. And auger doesn't really make and noises other than a little snap now and then when a pellet gets jammed.

 

[Lousyweather]

ok, stove is shut down, going to look for a hole by the end of auger. Going to putty the bottom holes in burnpot back up. I had them puttied over all last year and got a better higher burn. Was getting a little smoke earlier this year and tried cleaning them out to see if that helped. Slideplate is fine, clean as a whistle. Stove pipe is good, stove adapter used and all joints are well caulked. dealer lent me a Circuit board to try to rule that out, and my circuit board works same as his. Upper hopper seal is brand new, and all the joints butt up to each other good.

Lower hopper seal, I have no idea, can it be accessed without taking hopper off?

I am suspect of hole in auger tube, or burnpot gasket, or lower hopper seal.

Stove is 9 yrs old to answer an earlier question. new comb motor last year.

lower seal....just rtv it up, WITHOUT removing the hopper, please

 

[Honda]

Ok, Just cleaned the stove top to bottom. Couldn't see any hole burned in the augertube where it meets the burnpot, as suggested by Ivanhoe. There was a little carbon in there though, scraped it out. Wiggled auger, only a tiny bit of play, wouldn't touch the tube walls or anything.

I plugged the 5 bottom holes in burnpot with putty, as I had done in the past. Fingers crossed, it is running way better. Higher, brighter, hotter flame, and seems to be feeding consistent and holding a consistent temp. Now to get to the bottom of the whistle noise, will try the rtv on bottom of the hopper next sunny day and the stove is off.

 

[Bioburner]

That's what I said. The machine works on negative pressure. And I also did say that air would be coming into the auger tube from the auger bearing and not blowing out. The only part of the machine that is under positive pressure is from the combustion blower paddle fan going out the vent pipe. And I have seen so many holes in the auger tubes in Harman stoves over the years that did NOT have the 5 holes in the bottom of the burn pot. So I do not believe that the 5 holes is entirely to blame.

OP said the smoke was coming out when he shut down to change the probe so no vac when seen smoke.

 

[Honda]

OP said the smoke was coming out when he shut down to change the probe so no vac when seen smoke.

exactly, no vacuum. no blowers running.