Harman P43 Problem

[MrJitters]

I have had my P43 running for about 3 months now with no problems whatsoever until recently. During the recent cold wave, which saw my local temps plunge to -33F, a rather odd thing has happened. The flame will change from it's usual and typical pellet stove flame to what I can best describe as a rather "lazy" wood stove type flame with smoke and soot on the inside of the glass. The stove temp will increase from it's usual 500-600F temp (measured on the side of the fire box) to over 700F and with a slight smell of "hot metal".

The stove is cleaned completely every week and the burn pot is scraped at least twice a day or more while running. Today the problem started a half an hour after the burn pot was scraped and cleaned with a feed rate at between 3 and 3.5. So much for a dirty burn pot theory.

I am running ICC Excell Pellet Vent pipe 4" with an EVL of 19. I have a 3" outside air intake of approx 10' in length with 3 90 degree bends from intake to stove attachment.

Given: So far this has only happened when the outside temp is well below zero. This morning it was around -11F when the problem occured.

I have temporarily disconnected my outside air intake with the thought that if this only seems to happen when it is below zero, than possibly it could be the cold air causing some problems. ?????

In the pic below, the vent pipe rises another 4 feet and exits horizontally through the wall.

My dealer says it is dirty pellets causing too much ash, but cannot agree with that. First of all, as I stated, we clean the pot at least twice a day, and secondly, doesn't Harman brag about how good their bottom feed system is in burning all types of pellets?

Any thoughts on this would be greatly appreciated.

 

[tinkabranc]

Have you checked your vent pipe for ash buildup?
Especially that long horizontal one attached to the tee?
May not be your issue, but something to check

I do not have an oak on my stove but have run into that hot metal
smell once before. It happened just a few days after a cleaning.

vertical vent pipe was clean as well as the Tee cap, but the horizontal piece
was packed full of ash. After cleaning that out, the smell went away and has not
returned since.

 

[mark d fellows]

I have to say your trouble shooting skills sound solid to me. I'm sure you'll figure it out.

When you were talking about a lazy flame I was thinking combustion fan, but blocked vent pipe sounds better since I don't think a combustion fan would quit when it was cold out.


I bet someone could explain the physics of why a partially blocked vent pipe would act up in extreme cold with an outside air kit. Seriously, that is interesting.

 

[tkrock]

The P43 is an experiment stove right??? I heard thats the P38 but with Automatic start. First time they came out was 08 if I'm correct. Wondering if any similar issues with the same model and just not a lot of talk yet being so few????

 

[MrJitters]

The P43 is an experiment stove right??? I heard thats the P38 but with Automatic start. First time they came out was 08 if I'm correct. Wondering if any similar issues with the same model and just not a lot of talk yet being so few????

Correct, the 43 is basically a 38 with 68 electronics. That may be somewhat of an oversimplification, but basically that's it. I felt comfortable with it since day one because I felt all the parts were tried and true, just the first time they were all together in this package.

I am going to look more closely at that horizontal piece. I've been thinking about that as well.

Temp this morning at +14.4 with no trouble overnight. Feed rate @ 3. Great fire and heat. OAK still disconnected.

Thanx for all the imput, guys.

 

[crausch]

You said that you disconnected the OAK. Is it burning any better that way?

I am not familiar with your stove model but if your air intake port is like my Harman, than you have a metal flap/damper inside the air intake of the stove. Perhaps the super rigid temps you are seeing is causing this flap to stick or freeze only partially opened, not allowing enough combustion air into the stove and thus causing a lazy flame.

If your stove works with the OAK off, then you have isolated the problem to the air intake system. Look at your intake flapper and see how freely it moves, then hook your OAK back up. If it happens again, pull the OAK off and check the movement of the intake flapper.

 

[Yardbird]

You say that you scrape the burn pot twice a day. Let your stove cool down, take a wire, like a piece of clothes hanger, and clean out the holes in your burn pot. Pay particular attention to the holes closest to the auger. Clean those holes really well, then clean out under the burn pot by removing the wing nuts on the bottom, then remove the ash by GENTLY using your finger to move the ignitor wires in there around. Once that's done, put it back together, and see if you have a better flame.

The reason I think those holes are plugged is because you scrape twice a day, and it sounds like you might be burning pellets with a higher ash content. I could be wrong, but try the simple things first.

 

[tkrock]

You said that you disconnected the OAK. Is it burning any better that way?

I am not familiar with your stove model but if your air intake port is like my Harman, than you have a metal flap/damper inside the air intake of the stove. Perhaps the super rigid temps you are seeing is causing this flap to stick or freeze only partially opened, not allowing enough combustion air into the stove and thus causing a lazy flame.

If your stove works with the OAK off, then you have isolated the problem to the air intake system. Look at your intake flapper and see how freely it moves, then hook your OAK back up. If it happens again, pull the OAK off and check the movement of the intake flapper.

I'm with codebum..... sounds very logical

 

[MrJitters]

Some great ideas guys!! I will most definitely try all suggestions. Tomorrow I will clean the holes in the pot during my weekly maintenance. Good advise on the flapper as well. Trouble is, it's +28F here right now and this problem won't occur again until the temp drops about 40 more degrees. The good news is -15-20F is expected this weekend so I can resume my trouble shooting. The stove is running right now at a 2 feedrate and is running great.

Yes, I still have the OAK disconnected. The reason I went with the OAK in the first place was to meet code clearance requirements. Consequently, it is not an option for me to leave it disconnected for any great length of time. However, I will take whatever time I need to isolate the problem.

I thought as well that possibly my pellets were producing more ash than normal, but I have nothing to compare to as this is my first year burning. So, I went to a local dealer and bought a few bags of Appling brand pellets. A quick and very unscientific analysis showed very closely the same amount of ash. The Harman advertises that it will burn high ash pellets, but one may need to clean more often. I clean often so theoretically that should not be a problem. I don't know.

Again, thanx for all the input. Everyone here is most helpful and a tremendous resource.

 

[mark d fellows]

I liked the P38. Two things threw me off of it. My girlfriend didn't like it and it was fully manual.

Mark

 

[GVA]

Mr Jitters, Where's your room temp probe going...

 

[MrJitters]

Mr Jitters, Where's your room temp probe going...

Upstairs in the main living area. Works good, when I use it, but most of the time I just leave the setting on stove temp.

 

[MrJitters]

***UPDATE***

Thoroughly cleaned the stove on Friday. Found a few holes plugged in the fourth row of the burn pot, removed wing nuts and cleaned inside around the ignitor. Cleaned stovepipe and determined there was no ash buildup possibly restricting flow on the horizontal sections.

Reconnected OAK and started the fire

Friday 1/23: temp around +30F feedrate at 1.5 and no problems.

Saturday 1/24: temp around +10F feedtate at 3 and no problems

Sunday 1/25 3:00AM: temp at -22F feedrate at 4 and the problem has resurfaced. Very lazy flame with high levels of soot on the inside of the glass. Hot metal smell prevalent throughout the lower level of the house. Temperature on the side of the stove at 700F. As per an earlier recommendation, I disconnect OAK and check flapper. It is working normal. Second thing I notice is the flame starts to return to a "normal" state as soon as the OAK is disconnected. I open the door and quickly wipe the soot off the glass so I can see things. I close the door the flame builds back up to a normal pellet flame. No lazy flame or soot buildup. The stove temps drops to a normal 600F when the feedrate is at a 4. I made no other adjustments to the stove. I did not scrape the pot or adjust the feed.

This is interesting. Right now it appears, for some odd reason, that extremely cold intake air is somehow affecting the operation of my stove when run at a high feedrate. I have no explanation for this. :question:

 

[GVA]

maybe the fact the air is so cold it is thinner? I don't know.......
but pulling preheated air from the inside seemed to have helped......
Selkirk has a pipe in a pipe to
A) use 1 pipe for exhaust and fresh air.
B) I would think to preheat the combustion air

 

[MrJitters]

Well, the stove has been running all day @ a feedrate of 4.5 for testing. Everything is running fine. The OAK is disconnected, it is +17.5 outside but the stove doesn't know that. At this point I would have to say it is looking more and more like the frigid air is somehow affecting stove operation. Any thoughts or theories would be appreciated. I believe I have found the problem but not the cure.

Of course, I could always upsize the incoming air line to 4" in an attempt to compensate for the thinner air. I'm just not sure that would help. Gotta think about that one. :question:

 

[SmokeyTheBear]

The really cold air in the OAK just might be causing the pipe to reduce just enough in diameter to stop the flapper from working correctly. The colder the temperature the more metal contracts. I can't imagine them putting together something that close in tolerance for you experience what you are. Now what does the outside area around the OAK look like in particular the outside screening/protector .

 

[SmokeyTheBear]

Oh one other thing cold air is denser than warm air so that aspect isn't the problem.

 

[MrJitters]

The really cold air in the OAK just might be causing the pipe to reduce just enough in diameter to stop the flapper from working correctly. The colder the temperature the more metal contracts. I can't imagine them putting together something that close in tolerance for you experience what you are. Now what does the outside area around the OAK look like in particular the outside screening/protector .

It's all clear. Early on I checked for the possibility that frost could be collecting on the mesh restricting flow. Turned out to be a non issue.

 

[SmokeyTheBear]

I wasn't thinking about frost. I was thinking about anything that as part of the OAK would contract or if anything was in the OAK that would expand (like water freezing in a low point of the OAK. You are looking for what amounts to a restriction.

 

[MrJitters]

I wasn't thinking about frost. I was thinking about anything that as part of the OAK would contract or if anything was in the OAK that would expand (like water freezing in a low point of the OAK. You are looking for what amounts to a restriction.

Hmmm, good point. I will check for any water in the line. Thanx.

 

[bwoy]

Your stove is suffocating. Black soot or smoke on the glass and a lazy flame is a sign of a draft issue. With your OAK disconnected it burns ok. Your problem is with your OAK. Colder air is heavier and on a longer pipe run, the stove will have trouble pulling more air through. You can do two things since your obviously want to keep your OAK to meet code. You can increase the size of the pipe on your OAK. eliminating some bends may help too That seems to be your problem when the air gets cold. Hope this helps.

 

[SmokeyTheBear]

Cold air at the same elevation is denser than warm air at that elevation, however air becomes less dense (both cold and warm) at higher elevations. That the issue is a draft issue is a given. Metal also contracts when it gets colder so it could simply be that the cold air reduces the cross sectional area of the OAK acting as a restricter and your suggestion of going up a size or so for the OAK would work. I believe the OP already has said that was an option if needed. He might also be able to reduce the effective vertical height of his venting and thus help the combustion fan move the air. Removing one of the bends in his OAK, the area where that enters his stove "looks like" there are two bends, would also help.

 

[MrJitters]

Pyro Gyro:

Thanx for the input on a different fan blade. How would that affect my stove during "normal" temperature conditions? Right now it runs good until -12F or so. I sure don't want to solve one problem by creating another. BTW, I am around 800 feet above sea level.

I have no problem upgrading my combustion air line up to 4", however I would prefer to wait until spring to do so. Which do you think is a better fix for me, the hi-altitude blade or bigger air line? I am leaning toward a bigger air line.

Smokeythebear:

When I upgrade the size of the combustion air I will also lose a bend in the process. Always good to lose restriction in the line.

Thank you both for your help.

 

[bwoy]

the combustion blower blade won't work, upon further review, it actually pushes less air. Your best bet is with less elbows as smokey suggested.