Harman Advance hopper fire (chain drive auger)

[Phillip Brown]

Hello! My Harman Advance stopped sometime during the night. No blinking lights in the morning. I unplugged it and plugged it back in and it came on just like normal. We were sitting around and my wife noticed a burning smell. Like electrical. We always look for fire. Noticed a very small amount of smoke coming out of the vent on top of the stove just in front of the hopper door, on the left side. I took off the left side panel and couldn't really see any smoke or anything burning. Turned the temp dial all the way down to 50 (that is how we turn it off). Let it all cool down for a few hours (was not that hot since it didn't run long before we saw the smoke) and figured I better clean it out. IT WAS FULL! Okay so I was definitely negligent here. The ashes were all the way up over the burn pot and had burned in the burn pot in such s way as to create black solids that pushed the flame guide out from the back wall. Definitely negligent on my part. I cleaned everything out very well, put it all back together and turned it on. Started smoking again on the left side. This time I had a infrared temp sensor and noticed the board seemed really hot. I finally figured out that the very back of the auger feed housing was off the chart with my heat sensor (over 400 degrees). It was making everything hot! Then I noticed the wired that were touching it were melting and smoking. I turned it off Kept looking around in the back, opened the hopper and it seemed just fine (it was full). Started scooping out all the pellets because I had a bad feeling that fire had gone back up in the auger to the hopper. Got down to the bottom of the pellets in the hopper and sure enough there was a fire on top of the metal slide gate. I closed the hopper door and let it all burn out the last remaining handful of pellets. I did have to mist a little bit of water in there to cool it down and on top of the hopper lid to keep the lid cool because it was just hot enough to make the hopper door rubber gasket sticky. I didn't want it ruined. So I let it all rest of few days and cleaned up. Took the inspection door off the hopper slide door and there were hardly any fines in there. All seemed good. Then I started running it in test mode (no pellets) and watched the feed slide in the bottom of the hopper go back and forth, open and closed. All seemed fine but every couple of cycles it stopped when it was partly open. Now here is my question: Shouldn't the feed door be closing all the time at the end of any call for pellets? It doesn't. Sometimes the feed motor stops and leave the door partly open. Then I noticed that the metal slide has nothing to lock in place when it is closed. I think that his how my hopper fire started: The blocked burn pot basically filled the auger and shaft full of pellets and the auger, oddly enough, turns in the direction that opens the feed door. And that bothers me now. I am thinking my auger should have been made to turn the opposite way so it could never push open the slide door and so that it always stops with the feed door closed but it doesn't do that. It stops in random places and sometimes the feed door is open and sometimes it is closed. Is that normal design? I know it is not bullet proof for a hopper fire with this design. And again, I know I was negligent on cleaning, I was late and totally missed it. Thank you very much for all your help in advance.

 

[Mt Bob]

You created the problem,and the fire. If they created a pellet stove to account for every act of stupidity, it would cost 10 grand or more.

 

[DAKSY]

Almost sounds to me like the auger motor is the culprit. There may be a stepped gear inside it, preventing the auger from making a complete rotation. That complete rotation is how it closes the slide plate…

 

[Mt Bob]

A Harman auger does not depend on the slide plate being in any particular position when it stops. There is no "timing" or stop switches for this. It's main job is being a feed plate. The feed plate system gives a degree of fire protection, same as what the hopper lid gasket does. And they worked.
If you empty the hopper,and remove the slide plate,look down in there, you may be able to see how it functions.

 

[Phillip Brown]

You created the problem,and the fire. If they created a pellet stove to account for every act of stupidity, it would cost 10 grand or more.

Yes, I see that really kind of cuts right to the heart of the question: Was it my stupidity alone or was it the engineer who tossed a coin and said let the auger turn clockwise. No cost difference I can see whichever way the auger turns but it might prevent me and anyone else from looking stupid. Leaving the bottom feed door open when it is not feeding pellets, I don't know if that is a feature, broken mechanism or a defect yet.

 

[Phillip Brown]

Almost sounds to me like the auger motor is the culprit. There may be a stepped gear inside it, preventing the auger from making a complete rotation. That complete rotation is how it closes the slide plate…

That is kind of what I am concerned about is if the auger motor was damaged and no longer stopping where is should. It does make full rotations, it just doesn't consistantly stop in a position where the slide door is closed. I do only see two wires (hot and neutral) going to the motor so I don't see it having a way of knowing position. Maybe it is possible. There are also not any marks or instructions about aligning the gears on the auger and feed motor (chain drive) much the way you do with a timing belt on a car.

 

[Phillip Brown]

I took out he slide

A Harman auger does not depend on the slide plate being in any particular position when it stops. There is no "timing" or stop switches for this. It's main job is being a feed plate. The feed plate system gives a degree of fire protection, same as what the hopper lid gasket does. And they worked.
If you empty the hopper,and remove the slide plate,look down in there, you may be able to see how it functions.

I took out the slide plate and there is not much to see there. The slide plate is laying on another flat solid plate. The pellets are actually pushed over to the left of the opening I see then and drop into a slot out of view. So if there is not "timing" or stop switches as you say then it sounds like my auger motor is doing what is designed to do. It just rotates and randomly stops with the slide plate in a variety of positions. The things that stop the fire from backing all the way up the auger shaft is draft, space between pellets in the auger and of course me keeping the burn pot clear and ash pan empty.

 

[Washed-Up]

Keeping any pellet stove clean ensures a proper and SAFE heating appliance.

 

[gfreek]

Greetings , Are you the original owner of this stove ??

 

[Phillip Brown]

Greetings , Are you the original owner of this stove ??

Yes. Purchased new. Over the years replaced the ESP sensor (I think that is what it is called in the exhaust vent), ignitor and auger motor. Been a couple years since the auger motor was replaced and has worked fine since.