Harman Almost Smothered The Flame On Start-Up of Constant Burn #7

[Orson_Yancey]

Hi, Has this ever happened on your stove?
I have a Harman P68 that I purchased in June 2014. Last night, it almost smothered the startup flame and was about to start pushing unburned pellets over the edge of the burn pot, before I intervened. When I got home, I wanted to heat-up the house quickly. I set the dial to constant burn #7. (The feed rate limit was on #4 where I always leave it.)

I saw the flames of the fire start, but the fire did not grow to full size, across the full width of the burn pot. The fire was not putting out enough heat; hence, the feed auger continued to push pellets. It was as if the control system did not detect enough heat (big enough fire); hence, the control system thought that the fire needed more pellets and kept pushing pellets.

What happened next is the fire got partially smothered. Unburned pellets were about to be pushed over the edge of the burn pot. I decided it was time that I do something. I turned the feed rate limit down to 1/2. I set the dial to OFF. Luckily the feed auger stopped. It then took about 25 minutes for the fire to build-up to a normal size flame extending across the full width of the burn pot and about 1/2 down into the burn pot. It took this long
for the fire to grow and burn-up the large accumulation of pellets in the burn pot.

After about each 20 minute period, I gradually turned-up the constant burn dial about about two numbers. It took some 40 minutes or so to work up to constant burn #7.

Questions
1. Has this over happened to you?
2. Is the best way to reach constant burn #7 is to achieve the first fire on a constant burn #1 setting, then each 15 minutes move the dial up two more numbers?
3. I wonder how this would have turned-out had I not been nearby watching the stove start-up?

Any comments, thoughts, or advice would be greatly appreciated.
Orson
New Hampshire

 

[alternativeheat]

Ya you kind of asked for full demand before the fire was fully established. It probably should have handled that but I have to say I never tried start up that way. If to run constant burn on start up ( in my P61 that is Stove Temp Mode), I light it up around heat range 4. Once there is a decent fire I would crank it up then.

But let me ask you this, when is the last time you cleaned the compartment under the burn pot where the igniter lives ? If that gets a good ash buildup , ignition can be slow and you already now have started with a pretty full burn pot. When ever I get a strange start up in my stove I'm sure to clean out in there on the next shut down

 

[bogieb]

Did you by chance recently change brand of pellets? When I use smaller pellets I have to turn down the feed rate; FSU's for example which are about 1/4-1/2", versus ThermaGlo's which are 1/2"-2.5" (yes, that long) - the FSU's have a feed rate of 3 or less and the TG I set at 4 or a little above.

 

[Pellet_Pete]

I start my stoves with starter gel, so this happens to me enough if the fire hasn't burned into the pellets enough before I switch it on.

Just to cover your bases, make sure your ESP is clean too - that can delay startup temp detection if its sooty as well.

 

[jackman]

I'll second the previous posters and say I've seen the same behavior when the igniter compartment gets full of ash or if the pellets are damp.

 

[alternativeheat]

Did you by chance recently change brand of pellets? When I use smaller pellets I have to turn down the feed rate; FSU's for example which are about 1/4-1/2", versus ThermaGlo's which are 1/2"-2.5" (yes, that long) - the FSU's have a feed rate of 3 or less and the TG I set at 4 or a little above.

Good point, with FSU's I'm running between feed rate 3 and 3.5, where normally I run on 3.5- 4.25. That's all according to pellet size as well...

 

[alternativeheat]

I start my stoves with starter gel, so this happens to me enough if the fire hasn't burned into the pellets enough before I switch it on.

Just to cover your bases, make sure your ESP is clean too - that can delay startup temp detection if its sooty as well.

Yes indeed. I had a big flame start up today. I had the stove off for a while this afternoon and before I started it up again I decided to brush down the heat exchanger and sides of the fire box. I then went right into start up, I suspect the ESP had some of that dust on it because the flame really ramped up and for quite some time. I was about to either shut down or turn it down when the flame settle down and it's been fine all evening. I just cleaned the ESP last weekend, and only have burned maybe 7 or 8 bags of pellets all week so doubt it was dirty from burning that few FSU's.

Incidentally, these FSU's have been quite good. The bag stated Product Of Canada and these smell very much like Spruce Pointes and look very much like LaCretes. But I'm quite pleased with them and so is the stove, it's not gobbling them down like some of the crap pellets you can get out there.

 

[Orson_Yancey]

Ya you kind of asked for full demand before the fire was fully established. It probably should have handled that but I have to say I never tried start up that way. If to run constant burn on start up ( in my P61 that is Stove Temp Mode), I light it up around heat range 4. Once there is a decent fire I would crank it up then.

But let me ask you this, when is the last time you cleaned the compartment under the burn pot where the igniter lives ? If that gets a good ash buildup , ignition can be slow and you already now have started with a pretty full burn pot. When ever I get a strange start up in my stove I'm sure to clean out in there on the next shut down

Yes, I think I should always start-up at constant burn #1 until a full fire builds, then ramp-up the dial. It was about 15 to 20 bags ago that I
cleaned the igniter area. I plan tomorrow, to do a full cleaning of all of the inside of the box, including the heat exchanger and igniter.

 

[Orson_Yancey]

Did you by chance recently change brand of pellets? When I use smaller pellets I have to turn down the feed rate; FSU's for example which are about 1/4-1/2", versus ThermaGlo's which are 1/2"-2.5" (yes, that long) - the FSU's have a feed rate of 3 or less and the TG I set at 4 or a little above.

I have been burning North American Pellets about the past 20 bags. I too was thinking of maybe reducing the feed rate limit from 4 down to 3, just
to be safe.

 

[alternativeheat]

I have been burning North American Pellets about the past 20 bags. I too was thinking of maybe reducing the feed rate limit from 4 down to 3, just
to be safe.

I just do that with FSU because they are small.

 

[Orson_Yancey]

I start my stoves with starter gel, so this happens to me enough if the fire hasn't burned into the pellets enough before I switch it on.

Just to cover your bases, make sure your ESP is clean too - that can delay startup temp detection if its sooty as well.

Yes, the dirty ESP is probably the most likely reason. I have put about a total of 5 tons through the stove since I have owned it.
Never yet cleaned the ESP. Definitely on my work list as soon as we get some warm whether. I have never done it before. Need
to learn how. Perhaps, I can hold-off until the Spring. I do run the stove often on the lower heat output setting, which means the
changes are high that soot has build-up on the ESP. Thanks for the advice.

 

[alternativeheat]

Yes, the dirty ESP is probably the most likely reason. I have put about a total of 5 tons through the stove since I have owned it.
Never yet cleaned the ESP. Definitely on my work list as soon as we get some warm whether. I have never done it before. Need
to learn how. Perhaps, I can hold-off until the Spring. I do run the stove often on the lower heat output setting, which means the
changes are high that soot has build-up on the ESP. Thanks for the advice.

Often if the ESP is dirty it gives us a little signal, known good settings in known conditions starts eating more pellets than before. I have a narrow bottle brush ( nylon), when I dump the ash pan I pull the hatch by the combustion blower fan and I run that bottle brush in there over the ESP, it gets it pretty clean and certainly knocks the soot off. I rarely pull it out anymore. It's not like they get carboned up.

 

[Tonyray]

Often if the ESP is dirty it gives us a little signal, known good settings in known conditions starts eating more pellets than before. I have a narrow bottle brush ( nylon), when I dump the ash pan I pull the hatch by the combustion blower fan and I run that bottle brush in there over the ESP, it gets it pretty clean and certainly knocks the soot off. I rarely pull it out anymore. It's not like they get carboned up.

yep...
good ole bristle bottle brush....good point about No carbon buildup on the probe. Just a lot of powdery ash residue. really not needed to pull it.. maybe at end of season final clean with some Windex or whatever...

 

[Orson_Yancey]

Often if the ESP is dirty it gives us a little signal, known good settings in known conditions starts eating more pellets than before. I have a narrow bottle brush ( nylon), when I dump the ash pan I pull the hatch by the combustion blower fan and I run that bottle brush in there over the ESP, it gets it pretty clean and certainly knocks the soot off. I rarely pull it out anymore. It's not like they get carboned up.

Excellent way to quickly clean the ESP. Quick and often.

 

[alternativeheat]

Excellent way to quickly clean the ESP. Quick and often.

Yep.

Been snowing an hour here now, we shall see how this goes.

 

[Orson_Yancey]

I start my stoves with starter gel, so this happens to me enough if the fire hasn't burned into the pellets enough before I switch it on.

Just to cover your bases, make sure your ESP is clean too - that can delay startup temp detection if its sooty as well.

What has just occurred to me is if I every encounter again the situation of too large abundance of unburned pellets
in the burn pot while with too little of a flame having trouble starting-up (growing), when I intervene to prevent the situation from turning into something worse such as unburned pellets pushed over the edge of the burn pot; I think the solution is that I should flip the ignitor switch to manual so as to stop all further pellet feeding, until the fire can
build-up and start putting out heat. When the control system detects heat, it will feed pellets. What I am now understanding about the ignitor manual setting it that it will run the combustion blower, providing air for a fire, taking away any smoke, and wait for you to light a fire, -- however long that might be.

 

[alternativeheat]

Two things I have found : When I scrape the pot a couple of times a day give the burn pot a few good raps with the cleaning tool. That shakes ash off the igniter element and is suggested in the Harman videos. The other is the ash in that compartment under the burn pot. If I'm burning really ashy pellets I'm probably going to clean that out weekly when I shut down to brush down ash inside the stove anyway. Real clean running pellets I don't think about that. Seriously every time I have had a slow start up there has been a lot of ash in that compartment, every time, not most times. I've only had that occur maybe three times anyway. One time there was ash in there and also 4 burn pot holes were clogged, which has never happened since. Ya know in shoulder season I've had this stove starting up a few times a day, so it's had many many start ups that went just fine LOL !.

 

[Orson_Yancey]

Yep.

Been snowing an hour here now, we shall see how this goes.

Not a single snow flake coming down, here in Newmarket, NH (near Portsmouth).

 

[Tonyray]

Two things I have found : When I scrape the pot a couple of times a day give the burn pot a few good raps with the cleaning tool. That shakes ash off the igniter element and is suggested in the Harman videos. The other is the ash in that compartment under the burn pot. If I'm burning really ashy pellets I'm probably going to clean that out weekly when I shut down to brush down ash inside the stove anyway. Real clean running pellets I don't think about that. Seriously every time I have had a slow start up there has been a lot of ash in that compartment, every time, not most times. I've only had that occur maybe three times anyway. One time there was ash in there and also 4 burn pot holes were clogged, which has never happened since. Ya know in shoulder season I've had this stove starting up a few times a day, so it's had many many start ups that went just fine LOL !.

I pull the ash pan out, and hold a Paper plate in one hand and fingerout the dry ash letting it fall onto the paper plate..
[my lazy way of not having to vacuum it off the stove floor every time.]

 

[alternativeheat]

I pull the ash pan out, and hold a Paper plate in one hand and fingerout the dry ash letting it fall onto the paper plate..
[my lazy way of not having to vacuum it every time.]

I like that !

 

[Tonyray]

I pull the ash pan out, and hold a Paper plate in one hand and fingerout the dry ash letting it fall onto the paper plate..
[my lazy way of not having to vacuum it off the stove floor every time.]

can also put a couple sheets of newspaper on the stove floor and let it fall there also.

 

[Tonyray]

hey.. ever figure out what the original posters problem was with ignition and pellet overflow?

 

[alternativeheat]

Not a single snow flake coming down, here in Newmarket, NH (near Portsmouth).

It's all about ugly outside here LOL ! Now of course my wife likes it, but she won't be out snow blowing with 2/3 recovered knee surgery at the end of this thing. I don't know, the doc says he is releasing me but this thing doesn't seem right to me, clunk clunk,click, snap, walking like Frankenstein in HD yesterday . I'm not thrilled with the outcome thus far. But then I'll be 66 in April, last Knee surgery I was 27 LOL ! Maybe it's supposed to be frigged up at this age.

 

[alternativeheat]

hey.. ever figure out what the original posters problem was with ignition and pellet overflow?

He has a theory going on back about 6 posts ago Tony. I know we hijacked this thing.

 

[Orson_Yancey]

hey.. ever figure out what the original posters problem was with ignition and pellet overflow?

Hi Tom Ray, After having read many of the posts, in my opinion, probably the most likely cause of the problem is
ash on the ESP, causing it not to read as high as heat as it should. My solution for now is to start the stove on
constant burn #1 until I get a big fire, then adjust upwards.