Harman P61 "explosion" during startup

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mgambuzza

Member
Mar 12, 2006
204
Syracuse, NY
The other night my wife called me and said when the stove started, there was a lot of smoke, than a ball of fire and sparks came out of the stove. It scared the hell out of her and she was afraid of letting it run. Knowing my wife, I thought it would be best for myself to see this first before I draw any rash conclusions.

The other day, the temperature dropped enough for the stove to start up, I saw the auger feed pellets into the chute - almost too much pellets. Then during the normal ignition stage I noticed occasional sparks begin, then a tremendous volume of smoke filled the inner chamber. Suddenly it ignited with a bang - so bad I thought the glass broke - with smoke coming through the door frame, and every seam in the pellet pipe - she wasn't imagining. This has happened to me twice so far. I've resorted to leaving stove running in Stove Temp Mode so unit doesn't shut down in case the next "explosion" causes the glass to shatter.

Has anyone seen this happen before? I've had nothing but praise for this stove and this is the first issue I've encountered with it.
 
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imacman

Guest
Could it be due to the pellets having a lot of fines, and sort of making an "explosion" like you would see in a coal mine or grain silo that has a lot of airborne dust?
 

GVA

Minister of Fire
pyrolysis
All that smoke will actually ignite with a flash and a whooosh, sometimes you'll hear a loud bang from them intake flapper slamming shut.
2 possibilities
weak ignitor smoldering the pellets too long.
stove needs to be cleaned.
 

jtakeman

Minister of Fire
Dec 30, 2008
13,497
Northwestern CT.
www.facebook.com
I think GVA hit it!

My quad would do that when the holes in the burn pot were glogged up with scale. Blow the cap off the cleanout tee(old style that was foil taped on). I had to use a drill bit to clean out the holes. Never did it again. I started doing that on a weekly basis with the normal cleanings. Never had any problems after that.

I would check the holes in your burn pot and make sure there all clean. Ream them out to original size. Get all the scale build up out and see what happens.

Keep us posted.
jay
 

Bxpellet

Feeling the Heat
Nov 1, 2007
427
Bronx, NY
My Advance did it once, I got a lot of smoke than bang! Scared the hell out of me and the cat!
 

Kenny1

Feeling the Heat
Oct 20, 2006
305
Eastern ON
I had that happen with the Lauzon pellets we were using last year. However, the LGs we have this year does not seem to suffer for this effect.

I agree with GVA - start with a good cleaning under the burn pot, then maybe check the igniter.

Cheers
 

photogame

Member
Dec 2, 2008
17
northern ct
On my xxv 2 yrs ago it was almost a nightly event. It would scare the heck out of anyone in the family room. Even with a clean stove/ignitor it would still do it on occasion. the only thing that finally took care of it was switching pellet brands. so i will say my problem was with slow igniting pellets , to be more exact, pellets with to high of a flash point. so the pellets just smolder longer at iginition creating a smoke explosion when they do ignite. try finding a different brand pellet that has been stored inside. now wether it was a moisture issue in the pellet or just the junk pellet that i had that yr, i don't know. i hope this helps
 
RETIRED GVA said:
pyrolysis
All that smoke will actually ignite with a flash and a whooosh, sometimes you'll hear a loud bang from them intake flapper slamming shut.
2 possibilities
weak ignitor smoldering the pellets too long.
stove needs to be cleaned.

My thoughts exactly. The ignitor is causing the pellets to "smolder" and not fully ignite. Repositioning the ignitor to reach deeper in the pellets or replacing should do the trick.

In my case, if the ignitor gets weak, I just switch to the other hand with the match. :-S
 

SXIPro

Minister of Fire
Sep 28, 2009
705
Northern MA
Mine did it before when my combustion blower was messed up and not evacuating smoke from the stove quickly enough.
 

cac4

New Member
Jul 11, 2008
376
Essex County, MA
interesting. I wonder if its part of the design of the Harman burn pot/feed/igniter system. I've always noticed that on mine, the pellets sort of "leap" to flame, with a pronounced "poof". a very much less intense version of the OP's description.

this year, (year 2), I left a half a bag of pellets sitting in the hopper all season...from march to october. But before I lit the stove for the first time, I took the pellets out, and gave the stove a super-duper cleaning. (brushed the chimney, and everything). So the stove was as clean as it gets. I put the pellets back in, fired it off...it took quite some time for them to ignite...and a whole bunch of smoke. could not see the burn pot through the glass, it was that thick. (normally, its not that thick). BIG poof when they finally burst into flame.

being "not that cold" for "not that long" early in the season, these pellets didn't get used up right away...took a few burns. each ignition was the same. Once I finished them up, and loaded up some "fresh" pellets, the effect is much less. (although, not non-existent. these pellets I bought sat outside for a bit. long story. they're "ok", but they probably could have been better).

I'm thinking that the pellets that sat in the stove all summer absorbed a bit of moisture from the humidity, making them a little harder than normal to ignite.
 
L

Lousyweather

Guest
during pyrolysis, prior to actually having a flame, the heat causes the combustible component to gasify, causing smoke (which are primarily flammable tars)....we see this as the early smoke you get before a flame occurs...the thing is, this smoke is actually a combustible product, and, depending upon how much smoke there is (how long its accumulated), it can all ignite at once, causing a pressure wave which will seek the path of least resistance....usually, its out of the pipe, but if the door is slightly out of adjustment, or the gaskets arent sealing as well as they should, you might also observe smoke and/or sparks come out around the door when this combustion occurs. Of course, the longer the pellets smolder, the more smoke you will have, and the larger the explosion when it ignites. What causes these longer "smolder" times? A few things: weak igniter, dirty pellet stove, insufficient combustion air, to name a few.

I was working on a PF100 that did this once, scared the living heck out of me....these things have a huge combustion chamber! Im sittign there with my head maybe a foot from the unit, which I heard the intake dampers start to flutter and clank..."what the heck is THAT", I wonder....when WHOOOOOSH! the thing ignites, smoke comes out the margins of the door.....better than coffee to wake a guy up!
 

Souzafone

Feeling the Heat
Oct 12, 2007
305
Freetown, Massachusetts
Mine does this when the area around the ignitor becomes packed with ash. If there's a little cover over the ignitor held on with wingnuts, remove it and clean inside as best as you can, then rap on the burn pot a little to loosen whats left and get it all out. I'd check this before just condemning the ignitor.
 

pastera

Feeling the Heat
Sep 8, 2008
336
SE Mass
My Lennox T300 will do the same with some brands of pellet - it seems the ones that are harder to start (high moisture???) fill the chamber with smoke before ignition. When it does ignite the whole cloud of smoke goes up.

I am burning Potomacs this year and they start up very fast with little smoke so no big bangs so far.

Aaron
 

gpack

Member
Oct 24, 2009
31
SW Ohio
I had this happen on the Glow Boy once and just recently. Seems the ignition of the pellets took too long allowing the "smoldering" to occur and an inordinate amount of smoke built up in the burn chamber. As soon as enough oxygen to ignite, whoosh. huge flame. And yeah the wife grumbled about the smoke in the house...As noted in some of the other posts, I cleaned out the burn pot really well, including the holes. Hasn't happened again but I think there are a few things that can combine to make this happen including the dirty burn pot. Additionally on the Glow Boy there is a tab that adjusts where the burn pot sits in the burn box. I had to adjust this to "push" this back toward the igniter when start ups were failing. A slight tweak on the tab and I've had zero no starts on the stove. The jpeg isn't exactly what I've got but it shows the "tab" adjustment of the GB burn pot. ("F") BTW: Burning Pennington this year.
 

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rex66

Member
Apr 4, 2009
26
Central NY
I also have the P61A and I have noticed that if the area below the burnpot where the ignitor is gets a fair amount of fines in there it will do exactly what is described here. I am burning lignetics this year and although they don't give much ash in the ash pot they do seem to have a large build up of gritty fines that get into the ignitor area. I have to clean it every week or the starting will do what yours is doing. I have even timed the starts. It takes 5-6 minutes to have a nice flame when this area is clean. When it has the fines in there it can take up to 20 minutes and sometimes loads so many pellets that they will fall into the ash pot unburned. It's worth the effort of keeping it clean for me!

rex66
 

summit

Minister of Fire
Aug 22, 2008
1,900
central maine
if you have too many pellets in the pot on ignition, this will happen everytime... also does it if the air intake is blocked or the area under the burnpot (where the two wing screws are) is full of ash, thus restricting the airflow.
 

Honda

Member
Nov 28, 2009
74
New Brunswick, Canada
I have a Harman P-61A going on the fourth winter. In the really cold weather I mix some corn in with the pellets. It works great burning a corm pellet mixture, however, I noticed that the corn does not lite well, and I experienced the same situation as described in this post. My first time trying to lite on a corn mixture I immediately noticed something was not right, large amount of smoke, could not see the pot. Eventually it did lite, but I experienced the big whoof, high pitched squeal and smoke coming from every crack and crevice, unfortunately the smell of burnt popcorn. After this incident I would just lite manually when mixing corn. I have never experienced the situation while lighting with only pellets.

After saying this, I wonder if that whoof and high pitch squeal popped any seals? My stove has not really worked perfectly since. It tends to burn a low flame at settings that it would normally burn a good med-large size flame. It will also surge, fill the pot about halfway up, burn a good flame, and then slack off so much so that it appears to be in shutdown mode, and then it will feed the pot full again and repeat. Just today I noticed something strange as well. I noticed I was out of pellets, flame was almost out, opened the hopper lid to dump a bag in, and the hopper was filled with thick smoke. I assume this would indicate a problem of some sort. I know something is not right because of this surging issue. I am speaking of stove temp mode that this occurs. It seems to work fine in room temp mode. No matter what my temp setting and feed rate are, it consistently does this surging thing and does not throw consistent heat. My dealer is on his way today to check the ESP probe and draft.
 

Elad

Member
Oct 31, 2008
19
Northern Mn
Hehehehe
Same thing for me when I too picked up some loose pellets that fell on the floor and I tossed them into the pot while it was running.
Big mistake that I won't do again :)
It put out the flames and then also had hugh smoke, then boom, then cat ran away :) (a bright side effect to a boo boo)

Wow Rex66 - 20 minutes after a week? I'd say its time to try another brand if your getting that much fines.
 

Czech

Minister of Fire
Jan 20, 2006
1,076
Twin Cities, MN
I love it when my stove does that, the suspense is a killer! Black oiler sunflower seeds are notorius for this. That said, GVA and others hit it on the head, delayed ignition for some reason, in my experience usually fuel related, but again that's my experience.
 

maglite67

New Member
Dec 18, 2009
145
WI
I can make any stove have a violent igniton on harmans it's either stove cleaning or setting on the control board and possible the pellets.
 

Honda

Member
Nov 28, 2009
74
New Brunswick, Canada
Strangely enough, my dealer was here yesterday to do some tinkering as per the low flame problem. the stove was off and as he was frigging around the pot got full, neither of us really noticed and when he was done, turned the stove on to ignite, the pot was super full, man, did that baby ever throw some smoke out the pipe and fill the stove. It was so thick you could cut it with a knife. Talk about suspense, I knew the puff was coming, and did it ever let a whoof out. First time I had seen it do that with pellets, but like I said, it was really full.
 

ramdez

Member
Dec 29, 2009
51
eastern PA
mine did this on the 3rd bag ever run thru it. It cycled off through the thermostat getting to temp then i poked around a lot and stirred up the embers and stuff then i turned the thermostat up a bit so it would light again, it fed a bunch of pellets in.... got real real smokey then boom.. and smoke cleared and fire burned great :)
 

ramdez

Member
Dec 29, 2009
51
eastern PA
I realized that whenever mine would do this it was because my igniter was covered with ash under the burn pot. this would cost the build up of smoke and heat and way too many pellets and then finally boom it would light and throw smoke out of the door seals. once i vacuumed out and cleaned the ignitor up it would light much faster and not do the BOOM.
 
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