Harman P43 Explosive Ignition

[Navig8ur]

Hello

I just replaced my troublesome 12 year old Kozi model with a Harman P43 and have encountered an interesting problem. Twice during the first month of operation, while operating the unit in automatic mode, the ignition sparked a fireball and very loud bang and resulted in soot and smoke entering the house from around the door as it was displaced by the overpressure. The dealer has been great and arrived within an hour of the second event.

They think it may be the ignitor not starting the pellets quick enough and that too many pellets are in the pot when it eventually does start. I have searched and cannot find anyone who has experieinced a similiar problem and would like to have the thoughts of others who are more familiar with the Harman stove.

The dealer will be replacing the ignitor and I am using the stove in manual mode until then.

Any advice or thoughts on the matter is very welcome.

 

[mrbean1025]

I've had a similiar situation. The burn pot had way too many pellets when it ignited. There was no "bang" but there was a suttle pop when the pellets ignited. I don't let the pot fill that much anymore and have not had it happen again in a few years. Good luck.

 

[BJN644]

it happens on mine when I run out of pellets and restart the stove. It ends up putting to many pellets in the pot and makes to much pyro gas causing that mini explosion. If you run out of pellets, or are firing a new stove, run it in test mode for a minute to fill the tube with pellets. If you don't you end up with an extra charge of pellets, and you know the rest.

 

[jtakeman]

There are several issues that can make a stove smoke before ignition and then pop(ask any quad owner). But I would check them pellets for moisture.

What pellet brand are you using?

 

[Navig8ur]

I've been using Shaw Pellets since '99 and have not used anything else so I don't really have anything else to compare them with. They seem to have a monopoly here in NS.

 

[Buck Hunter]

I had the same problem once with my Enviro Omega, after a good cleaning I thought I wound be smart and prime the burner pot a little before starting it, a couple handfulls of pellets should help, lots of smoke on start up and quite a pop, think I will be smart now and let the stove start itself LOL.

 

[Brune]

I faced a similar problem last year with my P61. The problem is caused by a lack of oxygen during start-up (incomplete combustion). The igniter heats the pellets which creates CO, CO2 and water. Once the temperature reach a certain level and once the amount of oxygen is high enough, a very fast ignition happens, the gaz expands volume and then....boom. This can be very dangerous.....
An improper incoming airflow into the stove or a problem at evacuating the exhaust gas may cause this problem....or too many pellets in the burn pot during ignition.

Regards,

 

[AndrewChurchill]

I had the same problem and it was due to the auger feeding too many pellets into the burn pot on ignition. There are usually 3 DIP switches visible and moving them up or down increases or decreases the amount of pellets fed into the burn pot.

I have it setup so the first two switches are in the up position and the third is in the down position. This decreases the feed time by about 30 seconds and that resolved my explosion issue.

 

[Lousyweather]

I had the same problem and it was due to the auger feeding too many pellets into the burn pot on ignition. There are usually 3 DIP switches visible and moving them up or down increases or decreases the amount of pellets fed into the burn pot.

I have it setup so the first two switches are in the up position and the third is in the down position. This decreases the feed time by about 30 seconds and that resolved my explosion issue.

uh....PLEASE be wary in changing dip switch settings! Incorrect settings can cause a myraid of problems, all of which ARE NOT covered under warrantee....and if the tech who comes out to fix the unit doesnt know you changed the settings, could be qa real waste of time for her or him.....

 

[AndrewChurchill]

I did a lot of research and knew what I was doing before I changed anything, but thanks for your concern.....

 

[Spartan]

I don't have a pellet stove (yet) but the spontaneous ignition was a problem I faced when I was running a wood stove. Basically, you are creating volatile gases through your heating mechanism (igniter) and because of the volume of gases, when it ignites, the entire mass ignites at the same time. Small Bang Theory...lol

Again, I don't have a pellet stove but right now, I'm researching into it and it appears that most use some kind of electric heater. From previous knowledge, what you need to do is increase the local heat (more intense) of the igniter to minimize the volume of gassing and speed up the ignition. The second issue may be high moisture content in your pellets. Basically, they take more time to ignite while more and more volatile gases build up. When they do......bang.

The moisture issue can be controlled by your pellet purchases, I don't know how much you can vary the self igniter. The solutions may lay in more pellets (smothering/insulating to allow for more localized heat), higher heat output from the self igniter (more heat, faster local ignition) or some combination. It may be an development/engineering problem beyond your abilities and I suggest that if you are not sure, then don't try it.

That is my two cents worth......and please be careful.

 

[slls]

Never had a pop with my Quad, chamber fills with smoke, fire lights, smoke goes away. I often wondered how you get a stove to pop.
I do keep a very clean stove.

 

[Spartan]

Never had a pop with my Quad, chamber fills with smoke, fire lights, smoke goes away. I often wondered how you get a stove to pop.
I do keep a very clean stove.

You don't build enough volatile gas concentration to create the situation. For example, fireplaces send unburned volatile gases up the chimney, but because they are low concentrations, they don't explode. However, they probably condense on the liner.(tar).

BTW.....

To the poster with the explosion problem. If you can control the burner box fan, perhaps you can turn it higher (more fresh air) to decrease the volatile gas concentration in the firebox.

In total...

More heat to speed the ignition therefore less time for volatile gas build up.

More pellet to smother and localize the heat which may speed the ignition and therefore less volatile gas concentrations.

More fresh air to reduce volatile gas concentrations in the firebox.

That's only my layman's opinion...and please be careful.

 

[Navig8ur]

Many thanks to all who have responded with their thoughts and advice. Until the tech replaces the ignitor and I feel comfortable with the fix, we are operating the unit in manual mode. The idea about reducing the feed rate at start up seems to make sense as the tech felt that it was too many pellets in the burn box that may have contributed, although he frankly admitted that this was his first encounter with this problem. Quick question to the poster who provided this advice, how did you reach this conclusion?

The pellet moisture may be an issue although they are new and I've used this brand for 11 years with no issues.

Thanks for all your help.

 

[Delta-T]

most common culprits for something like this is simple dirty igniter, maybe some clogged holes in burnpot, or the combustion blower speed might be a lil high...or combination of the 3.

 

[DERUBIS]

Had same problem with a Harman PB105 Boiler. Dealer replaced the fan motor. They are not sure what caused the explosion.
I just replaced my troublesome 12 year old Kozi model with a Harman P43 and have encountered an interesting problem. Twice during the first month of operation, while operating the unit in automatic mode, the ignition sparked a fireball and very loud bang and resulted in soot and smoke entering the house from around the door as it was displaced by the overpressure. The dealer has been great and arrived within an hour of the second event.

They think it may be the ignitor not starting the pellets quick enough and that too many pellets are in the pot when it eventually does start. I have searched and cannot find anyone who has experieinced a similiar problem and would like to have the thoughts of others who are more familiar with the Harman stove.

The dealer will be replacing the ignitor and I am using the stove in manual mode until then.

Any advice or thoughts on the matter is very welcome.[/quote]

 

[AndrewChurchill]

I did a lot of research and found that the pellets in the burn pot don't need to cover the ignitor in order to light. A contributing factor in all this was the ignitor at the time was a 250 watts and had 13 fins. The ignitor was too weak to ignite the pellets quickly and the result was the pellets would smolder and I would see so much smoke coming out of the exhuast that I couldn't see my neighbor's house.

Once I reduced the amount of pellets feeding into the burn pot at start up the amount of smoke reduced substantially and my ignition times dropped from 12 minutes to about 8. Once the new 306 watt 15 fin ingitor was installed my start up time dropped to 4 minutes or less.

I stopped having the explosive ignitions once I reduced the amount of pellets fed into the burn pot at start up. I'll have to time it but I think the pellets stop feeding after 3 minutes.

I would suggest reducing the amount of pellets during start up. The worst thing that will happen is your boiler won't start. If that happens increase the feed time until you get a consistent ignition.

Many thanks to all who have responded with their thoughts and advice. Until the tech replaces the ignitor and I feel comfortable with the fix, we are operating the unit in manual mode. The idea about reducing the feed rate at start up seems to make sense as the tech felt that it was too many pellets in the burn box that may have contributed, although he frankly admitted that this was his first encounter with this problem. Quick question to the poster who provided this advice, how did you reach this conclusion?

The pellet moisture may be an issue although they are new and I've used this brand for 11 years with no issues.

Thanks for all your help.

 

[checkthisout]

Mine did this a couple times but only when like others said, the burn pot was overfull from the stove having snuffed itself out on a low burn setting. On my stove, it's a quick and easy way to clean to clean airwash vents around the glass. LOL

The pellets that did this were also slightly damp (the wrapping had a hole in it).

 

[rickwai]

It could very well be a fuel issue. Try a bag of differennt pellets just to rule that out. I doubt it was a igniter issue.

 

[Harman Lover 007]

Many thanks to all who have responded with their thoughts and advice. Until the tech replaces the ignitor and I feel comfortable with the fix, we are operating the unit in manual mode. The idea about reducing the feed rate at start up seems to make sense as the tech felt that it was too many pellets in the burn box that may have contributed, although he frankly admitted that this was his first encounter with this problem. Quick question to the poster who provided this advice, how did you reach this conclusion?

The pellet moisture may be an issue although they are new and I've used this brand for 11 years with no issues.

Thanks for all your help.

Hey Nav,

You are being offered alot of advice here but please be wary of any of it that doesn't apply to your Harman. Just be sure to mention to the tech when he comes that the feed time for initial startup is adjustable via the dip switches on the back of the control board. If he's a Harman tech, he should know that. My Harman P61A had the same problem. A couple of dip switch changes and not an issue since. You are on the right track...wait for the tech and run it in manual mode.

 

[Navig8ur]

As it turned out it was an ignitor and it took three replacements but it is now working as it is supposed to. We have had two months of trouble free operation in auto mode.

It ignites in 3-4 mins every time.

Thanks for your help in this matter all.