Auber ATC and Lump Charcoal

Brad VA

New member
Hi All,

So far I've done two long cooks using the Auber ATC and lump charcoal on my 22" WSM (did a few using Kingsford prior). The main reason of switching from briquettes to lump is sometimes the cooks took 14+hrs and ash buildup was a problem. So the best solution after research was to switch to lump which has significantly less ash generation, which I did. First cook was done using Royal Oak and second used Simple Life (Kroger brand).

Two new problems have arisen- wild temperature fluctuations and sudden temp drop. With both charcoals and ATC, the smoker will get to temp and maintain just fine for a few hours. Then all of a sudden temp will swing up 20-30F above set to 20-30F below set, then even out with swings ~20F and ~10F above/below before leveling off to maintenance temps. This seems to happen randomly as for the first cook this happened twice (~4hrs and ~6hrs into the cook) and on the second cook once (~5hrs in) without refilling or adjusting anything.

Also temp die off is sudden. In the second brisket cook I had the pit holding at 235F for about 6hrs (one temp fluctuation as described above occurred but evened out). No real issues. Then within 6 minutes, the pit temp dropped to 190F and would not raise. Fan output was 100% but no pit temp rise, just maintaining at 190F. After reloading the grate and letting it catch it went okay and the ATC did a good job maintaining at 235F, just surprised it dropped 45F in 6min and wouldn't come back up. Can't think of what happened in the WSM to cause that (shift in coals?)

Have any of yall encountered these issues? How'd yall solve them or is it just the cost of doing business with lump and an ATC? I like the less-ash problem, but the temp swings give me anxiety and I never had that issue with briquettes and the ATC.

- 22" WSM
- Auber Instruments SYK-2615 with 10CFM fan
- Pit temp set at 235F
- Charcoal ring filled with unlit lump, topped with a chimney of fully lit lump
- Top vent fully open
- Only one bottom vent open (for the fan)
- No water in water bowl, just foiled for cleanup


I havent used lump.
But it seems to me what you describe is what happens when coals get ash covered, shift and collapse, and run low.

You may have too much air with poor distribution as well which leads to actually cooling at some point when coals are low, as well as short coal life.

The swings, are due to poor tuning parameters for the state of the coals, and capacity of blower. Lump burns hotter...because it doesnt ash. This also means it burns faster somewhat

As you saw, add coals and problem goes away. Good tell tale.

Ash buildup or coal bed shifting will always be an issue, controller or not. And it takes different tuning parameters to control well with low coals.....than with excess. Its not unusual for a coal bed collapse to initiate swings.

The more coals you use...the longer it will be stable. On my 18, it was about 6 hrs (before atc). I extended my ring to hold more, got 10-11 hrs before it needed attention. Usung atc, i adjust parameters late in cook sometimes to get it controlling tighter if it does begin swinging a little. But i can cook 20 hrs + with coals left still. But when it starts having problems, its a sign not much charcoal left, or not enough lit for temp you try to run.

So, amount, how its lit., tuning, all play a role.

I would insure you have an air deflector on inside to help air spread out. I made mine from muffin tin. Fill it up with max charcoal.and then some....dont use minion method...spread starting coals evenly on top......and limit your airflow when can pinch top vent partway with blower if too much air . And it sounds like briquettes may have been less trouble........

I was under impression that coal ring on 22 was more oversized than the 18s, but you can try extending that a little too and see if more coals helps it be stable longer. Cut a $10 piece of expanded steel from home depot and use little non-zinc bolts to hold it together. No need to pay $50 for a commercial one imo. I welded mine together, but its just friction fit into top of coal ring and hasnt budged , works great. I always use excess coals, and put new ones on top of leftovers next time. Keeps from running low during cook, even at 18+ hrs.
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