temp control and shutting down the egg

WileECoyote · May 2008

I have a large egg which is several years old. I have cooked numerous pork butts and briskets over the past few months and each time I had minor problems with temp control.

I would always start by cleaning out the egg completely, using a fresh load of WGC, layering the lump with big pieces on the bottom, and carefully setting the vent and daisy wheel based on the desired temp range which is usually 250-280. The egg always stabilizes within the first hour or so after lighting and then I put the food on and monitor it for another 1-2 hours making minor adjustments if needed to keep it in the zone. After this it would usually be rock steady without maintenance so I would set the alarm on my remote temp gauge and go to bed. At least twice during the night the temp will drift too high or too low and set off my alarm so I have to get up and adjust the bottom vent, clean out the fire grate holes with a stick, tweak the daisy wheel, etc.

I figured this was due to a bad seal and leaking draft door so I completely cleaned and rebuilt my egg with a stainless draft door, spring band, high temp silicone sealant, nomex lid gasket, etc. and I even cleaned the daisy wheel. I also replaced my fire grate with a new cast iron unit that had more holes than my old ceramic fire grate. I have cooked a number of low and slows since then and the same problems remain. The temp always stabilizes and remains within 3-4 degrees of set point for the first few hours but then it will drift high or low during the night, sometimes both. If my desired temp is 265 then I set my low point at 250 and high point at 280, always allowing a 30 degree range for minor variations which should be plenty of room.

It is not a fuel issue as I always have some lump left over after each cook. I tested the gasket seal and lid alignment and it is fine too. No cracks or holes in the egg or ceramic parts. Building the fire meticulously with very large chunks of WGC on the bottom, followed by medium chunks in the middle, and small chunks on top. I even tried using all large or all medium chunks but it makes no difference. My lump is not damp, the egg does not get wet, and the egg is shielded from winds or drafts.

What am I missing? Is it unrealistic to maintain a fire within a 30 degree range for 15-20 hours without using the DigiQ, Stoker, or getting up a few times during the night? I don't mind tweaking the temp when I am awake but it is a problem to have my sleep interrupted twice in a 7 hour period, especially when I need to work the next day. I have read many posts on here about temp control and I think I have covered all the basic items, yet many people report the egg being rock steady for long periods of time without tweaking so I must be doing something wrong...

Also, what is the best way to shut down the egg? My goals are to preserve the unburned lump and prevent excessive soot build up within the egg. I have been closing the bottom vent all the way and installing the ceramic cap to choke off the air supply as quick as possible, which seems to put out the fire fastest but I find that this causes more soot to buildup inside. I then tried closing the bottom vent and leaving the top open for an hour or so before I put the cap on, which reduced the soot a little but the egg was still pretty hot after that first hour so it takes a lot longer to shut down this way. Maybe it would help to stir the lump, scatter it, or remove the largest unburnt pieces before capping?

Cory430 · May 2008

I'll give it a shot. You are probably correct in that it is unrealistic to expect to be able to sleep uninterrupted during an overnighter without an aid such as the stoker. In the grand scheme of things 30 degrees is not all that much and a stiff breeze through the vent or ash clogging the air holes could change things in either direction. After I have gotten my egg REALLY stable, I am typically comfortable sleeping for about four hours before checking on things and then getting in another couple of hours of bonus sleep.

Sorry to confirm your worries,

stike · May 2008

if your egg is rebuilt, then the only variable is the meat, maybe? sounds odd, but it can affect the cook/airflow.

but that's only when you jam it full, and as the meat shrinks, airflow opens up and temps can go up. never saw it myself (i don't cook that much PP at once), but fishless said it used to happen to him.

are you cooking four or five butts at a time?

FWIW, my large is damn steady. 250 is its magic number, and she'll stay there forever, without any iossue unless i built the fire poorly, or ash gets in the way.

hmm. maybe ash. you using something with higher than normal ash production?

BlueHorseShoe · May 2008

If your egg is solid, then the only variables are wind, meat and ash.

Wind = draft up the shoot!

Meat = How much butt are you smoking?

Ash = Here is a link to nakedwhiz.com Lump Charcoal reviews, with ash production of each brand.

http://www.nakedwhiz.com/lumpindexpage.htm?bag

Good luck.... Let me know when you find the prob!

WileECoyote · May 2008

I appreciate the comments.

I am using Wicked Good Charcoal which has been awesome, but I have also tried Royal Oak and Cowboy. I had the same temp variance issues with all of them. Ash has not been excessive with any of them, although I do find that WGC has a bit less ash than the others. When the temp goes low I first try to open the draft door a little more, and if this doesn't bring it back up after 30-45 minutes then I poke out the ash holes in the fire grate and open the door a little more. This always brings the temps back up but then they typically go low again or sometimes high later in the night.

I only cook one butt or brisket at a time, all have been between 4-12 lbs. and nothing else on the grill with them other than the inverted plate setter, grid, and drip pan.

My egg is inside a table which is covered on 3 sides and has sliding doors in the front. My table is also under a carport with the house blocking the direction of the wind so the front draft door is protected by wind, rain, or other elements.

I am beginning to think that people's claims of eggs staying within 3-4 degrees for 15+ hours unattended are exaggerated. Maybe the DigiQ is the only answer...

stike · May 2008

i can't think of any reason you'd have this recurring problem. does it happen at the same point in the cook every time (say, at the end)? ...doesn't make sense.

i hate to tell you this, but with no exagerration, i have put a butt on at the start of a snowstorm, went to bed, and the egg was pegged at 250 at 6 this next morning.

sure, i had a cook or two go out, but usually the thing settles in at 250 really well. you don't NEED a powered vent, people have been cooking without them on the egg for years. they help, but there's something else going on here. we are missing something.

WileECoyote · May 2008

Thanks Stike. I too figured that something must be missing but I am stumped.

The low or high points don't seem to occur at set times or intervals, but if I had to guess then I would say that the first variance is after hour 5 and as late as hour 8, and the egg is generally pretty stable in the last 2 hours of the cook. Usually I only get two significant variances during the average low and slow cycle, rarely three.

I don't doubt anyone that reports a set temp which was the exact same in the middle or end of a low and slow cook. What I question is whether their egg actually maintained that exact temp for the entire duration of the cook. It is possible that their cook cycle experienced similar highs and lows but they would never know it if they didn't have a remote temp gauge with alarms properly set. Some people with remote gauges might also set a wider temp range and thus they would't get the alerts.

All of my reading and research led me to believe that the egg would hold a temp within 5 degrees for 15+ hours if properly setup and stabilized, however I have yet to achieve this despite lots of testing and troubleshooting. I am even ok with a 15 degree variance in either direction for a total range of 30 degrees but this just hasn't been the case yet.

Maybe someone else will suggest another factor. If I do end up getting a unit like the Stoker then I might set it up to monitor and record my cooks without using the fan, then I can post the graphs to see if we can spot a trend or common symptom. I would really prefer to master the temp control and cook without the elecrtonic gadgets for a while, then get a DigiQ or Stoker later as a convenience. One downfall to the electronic units is that they could possibly mask problems which would otherwise be detected and corrected...

Sundown · May 2008

Read all of the post below and it looks like every point was covered.

ONe small issue I can see is once you have stabilized the temp at 250º and you put the meat on. DON'T mess with the vents any more. Try not to make any adjustments. The meat will act as a big fat heat sink and suck the heat right up until it gets warmed up a little. Then the dome temp will come right back to 250º garr-ron-teed!

You are using the best lump, WGC. And the meat is the only other variable you have. Can't do a thing about that, every piece of meat is different.

I've had a couple of low and slows go to 20 hours and never had a variance in temp that I was aware of the whole time.

Don't try to correct a 5º difference you'll just make yourself crazy and heavens knows that will never go here in the Cult.

Mahi-Mahi · May 2008

If you assume you are allowing the same amount of oxygen to the egg all the time and producing the same amount of Btus from the one setting, than the dome temp is going change during the cook to some degree.

What was shocking to me was watching my grate temperature hold steady and the dome temp vary by as much as thirty degrees to hold the same grate temp. Granted it was raining and the Guru increased the airflow to hold a constant temperature as the egg cooled off from the rain.
I assume it may be more of where you live in some cases. Here in Iowa we are still having some large temperature swings in highs and lows. So with a low of 38 and a high of 70 the egg is not going to hold a steady temperture overnight. Your relative humidity in some areas changes a lot at night also. We do a manufacturing process 24 hours around the clock and at night changes have to be made to keep the same moisture level in the product. The egg is a large thermal mass but it still loses heat more or less heat depending on the conditions of the wind and temperture outside and relative humidity.

I do use the Guru now and it pretty much takes all the worry out of it. It also has a very nice ramping mode that lowers the grate temp as the meat gets closer to finished meat set point. It holds the meat in case you do not wake up in time.
I am not so sure their is an answer to your problem for doing long cook times other than something like a Guru.

WileECoyote · May 2008

Interesting comments Mahi.

I have been measuring the external dome temps as part of my research into fire safety when the egg is mounted inside a table. I have noticed that the exterior egg temps are pretty consistent even during significant outdoor temp variations so I assumed that the internal egg temps wouldn't vary much if at all due to normal weather fluctuations. The thick ceramic really isolates the egg contents so even a 40 degree drop or climb in outdoor temp shouldn't really impact the internal egg temps by more than a few degrees.

Perhaps the outdoor temp and humidity changes are impacting the amount of oxygen available to the egg. Dense, dry cold air contains more oxygen than light, humid hot air which is why performance vehicles utilize a cold air intake. If this were the cause of my problem then the colder night time air would introduce more oxygen which would make the egg burn hotter, but my egg almost always go lower on the first significant variation so I don't think this is it.

The only possible theory which seems to make sense is that the ash is clogging the fire grate which drops the temp after 3-4 hours since it takes a little while for ash to build up. Then I adjust the draft door to allow a bit more air into the egg which initially restores the desired temp for a few hours, however the ash eventually drops down through the grate and this allows more air inside which in turn causes the temp to climb. In a few cases the ash doesn't drop so it builds up even more and thus another low spot is hit and I have to open the draft door even more or clean the holes out with a stick.

The trouble is that I can't confirm this theory since you can't inspect the ash and fire grate visually while doing a low and slow cook with the plate setter installed. Also, if this were the problem then it would effect a lot of people and not just me, so I suspect that many people have similar fluctuations during their cook cycle but they either don't notice or don't care.

I just don't see anything else that it could be. I might try to get the turbo grate from the BBQ Guru to see if this resolves the problem. I noticed a comment on the Stoker site about really large lump pieces not burning well, and my WGC has a lot of large lumps so maybe I need to break up the WGC a bit before loading it in.

whichcamefirst · August 2009

I can attempt an explanation.
Bear it out with me for a second.
Statisticaly variances occur in everything.
If you have upper and lower control limits you will meet those limits in the course of a cook.
If your upper limit is say 260 and lower limit is
180 then your alarm would register everytime you reach these limits.So you wake up and the egg is at lets say 265.you tweak the controls to bring it down.The statistic term here is "tamper".Now you go back to bed and in reality you have just "tampered" with your range 180-260.
So the egg will cool down a bit and go below your lower limit of 180 you wake up and "tamper" with it again
only to find it later at a higher temp than 260.
One would hope that if the egg is stable you should "AVERAGE" your desired temp in the course of a cook without having to tamper.Close monitoring during a day cook should confirm this for you.
Make sense??

stike · August 2009

big chunks of WGC, right?

small pieces aren't such a bad thing.

big chunks mean big gaps, and big gaps mean the fire might just be ONE chunk of lump. as it burns, it needs to contact new lump so the fire can grow. if you have big spaces, your fire may be restricted and grow cooler, until it finds more (new) lump

whichcamefirst · August 2009

I can attempt an explanation.
Bear it out with me for a second.
Statisticaly variances occur in everything.
If you have upper and lower control limits you will meet those limits in the course of a cook.
If your upper limit is say 260 and lower limit is
180 then your alarm would register everytime you reach these limits.So you wake up and the egg is at lets say 265.you tweak the controls to bring it down.The statistic term here is "tamper".Now you go back to bed and in reality you have just "tampered" with your range 180-260.
So the egg will cool down a bit and go below your lower limit of 180 you wake up and "tamper" with it again
only to find it later at a higher temp than 260.
One would hope that if the egg is stable you should "AVERAGE" your desired temp in the course of a cook without having to tamper.Close monitoring during a day cook should confirm this for you.
Make sense??

temp control and shutting down the egg

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