Recteq DualFire Burn Back

[SacSmoker]

Hello,

I’m a new dual fire owner and a pellet grill owner. I’ve posted a new thread about my new experience, but I’ve came across another issue on the direct heat side. I keep getting burn back in that tube. I’ve only had 2-3 short cooks on it, after which I decided to take it apart and clean it. I’ve noticed that the pellets were burned in the tube. I’ve vacuumed everything out and after another short cook (under an hour) I’ve noticed that the burn back still happened. The fire was completely evacuated out of the fire pot and in the tube. Compare to the indirect side before cleaning.

 

[Motodad1776]

That's alot of ash build up for only 2 to 3 short cooks, and it almost appears like the fan isn't running with enough force to keep the burn-back from happening. Those first 3 pics you can't even see the igniter tube as its completely covered in ash, piled that high can cause back burn in the auger tube for sure........I have very little ash build up even after several long cooks.

 

[v1per95]

I second @Motodad1776 thoughts on this. That looks like an unusual amount of buildup for just a few cooks, I would agree it seems like an airflow issue.

 

[SmokeOCD]

I like taking the contrarian view. What if there's too much airflow in that tube? Take away the air, there's no fire. It should be self smothering from the little bit of backburn that many of us get. The access hatch to the auger is a neat idea, but I wonder if it's also allowing air to feed the fire. Is there a gasket on that access hatch to the auger?

 

[RPopeilFan]

Since no one asked, what temp were you running on direct side? Did you shutdown from max temp and allow the shutdown cycle to finish?

The fact that there are "clean" pellets before the firebox would indicate to me that things are ok and the shutdown is stopping the auger and using the fan to stop active burning. Also, since the pellets still have a shape but are black would indicate incomplete combustion (unless you were using charcoal pellets).

I'm not sure how a completely uncharred pellet could exist in the first section of the auger (especially at high temps) because pre ignition from the firepot is uncontrollable and the shutdown process doesn't create an empty gap in the auger. Even with the fan blowing down the auger tube some thermal transfer will occur. Otherwise blowing on a fire to make it burn better wouldn't work.

 

[Waterboy]

I got the impression from OP’s post that the first photo with unburned pellets was the indirect side of the grill for comparison while the burned pellet photos were from the direct side of the grill where the problem exists.

 

[RPopeilFan]

I got the impression from OP’s post that the first photo with unburned pellets was the indirect side of the grill for comparison while the burned pellet photos were from the direct side of the grill where the problem exists.

I understood that as well. My opinion doesn't change. The photo reattached below shows fresh pellets at the back, charred pellets in the next section and burnt in the next visible section and assumed burned in the area we can't see.

If the fire pot is at grilling temps over 400° thermal action would influence each section of pellets in the auger. Yes, the fan is blowing but as a bellows not as a snuffing force. Like lighting the end of a smoke tube. Doesn't mean I'm correct. Just an observation.

 

[TheRicker]

I responded in the other thread you posted this problem on.

 

[Grilltreats]

That would be normal. You have to drop the temp down below say 275 before shutting down. There will always be pellets sitting at the tip of the auger chute on shutdown and if high heat remains, they will begin to smolder and could run back up the chute. RT's solution is to run the auger at the end of the shutdown cycle a short time to flush those smoldering pellets out but if the heat is still too high in the firepot after this cycle this doesn't work. I always keep my grill plugged in for about 30 minutes or more after the shutdown cycle ends in case, I have to run the auger manually again to flush more smoldering pellets out. In seven years, I have had to do this maybe three times after seeing smoke coming from the pellet hopper on my 700. It just depends on what temp I shut it down at and how the wind is blowing at that time. Keeping the hopper full helps prevent this issue a lot more as it blocks more of the wind from coming up through the hopper.