SmokeFire, auger & hopper burn back.


 
Bob Erdman

Bob Erdman

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Caught it in time, but I'm still trying to figure out how/why this happened. Little back story, grill was clean and hopper full, temp set to 225F, two 8 lb butts put on at 10 pm. Went to bed, wake at 5 am, check Weber ap, rock steady at 225F, butt temps at 153 & 163. 6am, lets check the pellets in the hopper, entire left side almost gone, right side never moved, I even have the slick tape on the ramp but they never budged. Leveled out the hopper went back inside. 7am, checked hopper, poked the top of the pile over the auger, noticed big drop of pellets, pellet void/flame out avoided? Temp still at 225f. 7:30 am, check ap, temp dropping...

This next part is where I can't explain how the burn back happened. Went back outside to see what the heck was going on. First thing I notice is no smoke from the vents but a decent amount coming from the hopper! Time to shut down and empty the remaining pellets. Butts putt in oven to finish the cook.

When I got close to the auger I saw a bunch of burned and smoldering pellets! ***! Looked inside the grill expecting to see a pile of pellets, nada. Fire pot had some caked up ash. With the lit pellets in the hopper, I thought there must have been a big fire in the cooker to ignite pellets in the auger. No evidence of that happening.

There was deffinately burning pellets in the auger, how the hell could that have happened? Wasn't the SF designed to avoid that? I'm still at a loss how this happened. Flame out, I would expect to see a pile of pellets. Pellet void, auger/hopper fire?

One of the reasons I got a pellet cooker was for overnight cooks. I can only imagine what would have happened if 10 lbs of pellet caught fire in the hopper while I was sleeping or away from home. Not a happy camper right now. The few smokes I've done since this problem have gone without incident.

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I have only had a "burn back" 2 or 3X. One was when I was playing around with a non factory controller on my MM (that one was on me). the other was when I simply did a "shut down" cycle on the MM after I'd done an extensive 475 deg run on it. I'd never done that before (shut down from a high temp). Someone on another group noted that on any pellet cooker, it's best to run the temp back down to say 250 and let it run there a while BEFORE a shutdown cycle. Explanation was: When running high temps an extended time, everything in there gets pretty super heated. Including the ashes, and the auger/tube themselves. Apparently that residual heat can be enough to trigger a fire in the auger/tube. Once I was informed of that, I have never done that (or had another auger fire) again.
On yours it's very hard to see how or why that happened. I don't see a way on a SF for a flame to propagate backward into the auger/chute. Glad you caught it before a disaster
 
LMichaels said:
I have only had a "burn back" 2 or 3X. One was when I was playing around with a non factory controller on my MM (that one was on me). the other was when I simply did a "shut down" cycle on the MM after I'd done an extensive 475 deg run on it. I'd never done that before (shut down from a high temp). Someone on another group noted that on any pellet cooker, it's best to run the temp back down to say 250 and let it run there a while BEFORE a shutdown cycle. Explanation was: When running high temps an extended time, everything in there gets pretty super heated. Including the ashes, and the auger/tube themselves. Apparently that residual heat can be enough to trigger a fire in the auger/tube. Once I was informed of that, I have never done that (or had another auger fire) again.
On yours it's very hard to see how or why that happened. I don't see a way on a SF for a flame to propagate backward into the auger/chute. Glad you caught it before a disaster
Click to expand...
Larry I was running 225f the whole time. Never had a problem when shutting down from much higher temps. IDK.
 
If I had to guess, my guess is that there’s a short in the motor assembly that superheated the auger that then fed the pellets back into the hopper. Granted that’s one hell of a stretch, but the possibilities are few.
 
I wonder if you had few brownouts or surges?
I know they sell surge protectors for pellet stoves, curious if we should have one for pellet grills.
 
timothy said:
I wonder if you had few brownouts or surges?
I know they sell surge protectors for pellet stoves, curious if we should have one for pellet grills.
Click to expand...
Been thinking maybe I should use a battery backup power supply on mine for those overnight cooks. Extra insurance. Though when my buddy and I finish the new added in 100 amp 20 space box we're going to install this week (doing double 100 amp so I can get 200 amp total service with 40 breaker spaces total), I will be also installing Square D whole home surge protector device. Figure as long as we'll be pulling the meter and shutting things down. Might as well. We get terrible surges lately. We're also going to pull and replace all the crappy aluminum wire from the meter into the box(es)
 
Chuck, motor looked fine, no evidence of it overheating, motor wires/connection looked normal.

Timothy, I don't think there was a surge or brown out. My kitchen stove clock was not blinking. Lol. Grill is plugged into an outdoor GFCI outlet.

I think pellet dust may have been a contributing factor to the auger/hopper fire.
There's an old post in this forum that Joe Anshien posted about a similar problem.
 
Bob Erdman said:
Chuck, motor looked fine, no evidence of it overheating, motor wires/connection looked normal.

Timothy, I don't think there was a surge or brown out. My kitchen stove clock was not blinking. Lol. Grill is plugged into an outdoor GFCI outlet.

I think pellet dust may have been a contributing factor to the auger/hopper fire.
There's an old post in this forum that Joe Anshien posted about a similar problem.
Click to expand...
That’s funny. About the only thing we use our oven for is the clock and power outage indicator.
 
Bob Erdman said:
Chuck, motor looked fine, no evidence of it overheating, motor wires/connection looked normal.

Timothy, I don't think there was a surge or brown out. My kitchen stove clock was not blinking. Lol. Grill is plugged into an outdoor GFCI outlet.

I think pellet dust may have been a contributing factor to the auger/hopper fire.
There's an old post in this forum that Joe Anshien posted about a similar problem.
Click to expand...

Interesting. I never really thought that dust could do tribute, but it makes sense.
 
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