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Adjusting the top vs. the bottom vent? What's the reason for adjusting one over the other?


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@kamado mofoFor smoking on the Akorn, you'll likely get the smokiest flavor when smoking at 275F in my experience.  I try to settle my Akorn around 235F after throwing on cold meat.  By the end of the cook, the thermometer should be reading 260-275F.  Any temp between 225-275F is going to result in tasty BBQ.  Akorn is usually happiest around 250F as far as stability is concerned.

 

@KaliforniaI generally set the bottom vent and make small adjustments to the top vent.  When your down in the low and slow range, it takes very little on the top vent to raise or lower temps after you set the bottom where you know it will work (for me, just covering the screw or roughly .75, top vent at .9 typically)

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  • 2 weeks later...

One other thing I've noticed is that the shape of the fire can make a difference.  If you set your charcoal bed in a volcano form, with a clear center passage, the grill is more sensitive to the vent settings, and you generally need smaller openings.  If you have a full, dense coal bed, especially if the pieces are smaller (end of bag), the grill seems to need wider damper settings.  I don't have evidence, but I would suspect that it will also more susceptible to temperature spiking on long cooks if a clear air path opens up through the coals.  Perhaps others can expand on this.

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  • 1 year later...

I know this topic is old, but Loremaster72's Question about shape of fire is quite interesting. Has anyone made similar experiences?

 

I have been trying to see what is the minimum amount of charcoal that I can use for a quick lunch steak grill. and wonder how volcano shaped or spread out banked piles can focus heat and how that in turn influences effectiveness of top &bottom venting.

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2 hours ago, cswschweiz said:

I know this topic is old, but Loremaster72's Question about shape of fire is quite interesting. Has anyone made similar experiences?

 

I have been trying to see what is the minimum amount of charcoal that I can use for a quick lunch steak grill. and wonder how volcano shaped or spread out banked piles can focus heat and how that in turn influences effectiveness of top &bottom venting.

I keep my fire box chuck full even for a short cook like your lunch steak. Once you finish cooking and shut down your kamado the fire will be extinguished by the lack of oxygen. What remains is burnable charcoal dusted with some ash. Not much is lost. I just keep topping off the load. Personally I think techniques like the volcano, ring of fire, and such are more adaptable for use in a traditional smoker. In the contained and sealed environment of a kamado I don't think the shape or configuration of your charcoal really matters all that much. I just load it up way past the air holes and keep it that way. Having a charcoal basket really helps because you can lift it, shake it, and then add new  charcoal to the burnable charcoal that is left. 

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Keeperovdaflame. Thanks for posting your thoughts so quickly! 

We are new to kamado grilling and have not yet experienced being able to shut down a full loaded grill and keep usable charcoal.  I think we've only done the full shut down on small amounts and it all burned through.  We will have to try it tonight with some sausages!  Thanks again for your perspective!

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Cswschweiz, you will find that, if you immediately close both the top and the bottom vents at the conclusion of your "cook," you will be left with a substantial amount of unburned charcoal.  For my "junior," I simply let it fall into the bottom pan, remove the pan, and pour it back into the charcoal bag for next time.  It's really surprising how little charcoal is consumed ... I think that this is because of the "convection oven" nature of the grill itself.  The meat is mostly cooked by recirculating hot air, not by radiant heat from the coals as in a "Smokey Joe."

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  • 6 months later...

With Akorn, I can't think of any great reason not to always keep a full fire box full of coals.  As mentioned, whether you're cooking for an hour or 18 hours, just shut down the vents and re-use whatever is left over.  After I replaced all my gaskets, the thing became so damn efficient that I'd look in my fire box after a 12-hr cook and it would look like only a couple of full coals had actually burnt.

 

As for starting the fire, I think the volcano method is good for a rookie - it's just too easy to light too much at first and you'll never cool it off.  Once you get the hang of temp controlling, it doesn't really matter how you light it as long as you don't light too much.  With my Akorn, I usually light in two spots with the wafer-style lighters and then just swirl the coals around after 8-10 mins and put in the wood and deflectors.  Again, it really doesn't matter once you get used to how much lit coals to start with.

 

I've found that control - with Akorn and even my KJ - starts at the bottom.  You should establish 'baseline' positions for each temp range, and adjust to those before getting to within 50 degrees of your target temp.  Then the bottom doesn't move.  Precision adjustments are made at the top.  For my Akorn, I've found that it 'locks in' with the bottom basically at the screw (so not even visibly open, but technically still letting some air in) and the top at not even a crescent moon.  Basically just enough for a pencil tip (just the tip) to get in.  If an adjustment is needed to raise temps, I bump the top by a bit, wait 15 mins to see where it settles in (you really need to wait for it to settle), then go from there.  Akorn is extremely responsive, and as long as you don't have wicked air leaks (which is common on many of them since it is, after all, a budget oven) it's easy to control.  That being said, I eventually modded it to work with Billows to control temps just for peace of mind while I'm sleeping, and haven't looked back.

 

Bottom line - fix the bottom to some baseline point that gets you within plus/minus 50 of your range, then only move the top during the cook.  No too cooks will be exactly the same, but it's a hell of a lot easier to only worry about making miniscule adjustments to the top because you have confidence in where your bottom is.  Plus or minus 30ish degrees is normal during a cook and nothing to worry about (can happen if using cheap odd-size charcoal, or windy conditions, or other factors) as long as it stays within that range.

 

I swear there are no intentional sexual innuendoes in this post.

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The “goofiest” thing to me, whenever I am cooking even for a long time, is that “the intake vent is almost completely shut, and the top vent is likewise only barely open.” So, where is it getting enough oxygen? :wacko:
 

And yet, the external-reading food thermometer reassures me that there really is a stable hot fire in there … the temperature of which for the most part does not change. And then, it lasts that way for many hours, virtually without attention. Here I am, poised to “fiddle with it,” and I just don’t have to. That sure did take a lot of getting used to.

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  • 2 weeks later...

I’m finding it hard to not fiddle with the vents and chase temps during a cook. Until my Thermoworks comes in I’m using an instant read thermometer gently placed in the seal to rest above the grate and its lack of damping to keep a steady temp makes me constantly want to adjust, especially if I see the temp start dropping.

 

Also I’ve found that my lid thermometer is off by 70 degrees or so. 250 on the instant read right above the grate reads at 180 on the lid…

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How are you deciding that your lid thermometer is off?  You're comparing measurements at two different locations.  That being said, after adding a KJ along with my Akorn, I find that the dome thermometer on the KJ is closer to the grate temp (in highest position) than the real dome temp is in my Akorn to the grate temp.

 

Regardless, I'm not sure that your method of checking is very accurate, since if you're using something like a Thermopen, it's likely only long enough to measure the  direct heat over the gap between the coals and the deflector, rather than the temp over the middle of the deflector which is where the meat would be.  

 

 

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@flynn, a relative new-comer here, so take with a grain of salt, but I started off by being sure my some thermometer was calibrated (it was pretty close, now it's closer), then ignore the actual reading during a cook.  I start with a target temperature, and really don't worry about whether the dome and grill are different.  The dome will be a decent index of whatever the grill temp is for a given configuration of grates, plates and fire.  So far, I've been able to pull off most of my cooks just with the dome thermometer and an instant read one for checking meat temps.  Longer roasts at low temp, I've used an inexpensive remote read thermometer.  But for higher temps, traditional BBQ stuff, I've seen more differences across the fire than anything else.  Just keep moving stuff around enough so it all comes out at the end and don't fret the differences too much.  Unless you're trying to sear a steak, of course.  

 

Short version, I don't worry about the specifics.  The grill will do a consistent job just based on the dome temp.  

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27 minutes ago, RoodyPooBBQ said:

How are you deciding that your lid thermometer is off?  You're comparing measurements at two different locations.  That being said, after adding a KJ along with my Akorn, I find that the dome thermometer on the KJ is closer to the grate temp (in highest position) than the real dome temp is in my Akorn to the grate temp.


I see your point. My probe most likely isn’t long enough to reach where the meat is actually sitting, but measuring both at the grate level between the lid and the body gives me 230, just inside the top damper is 227, and my lid thermometer is currently reading 160. I don’t know what to believe with it, but we’ll see how these ribs turn out. My Thermoworks Signals is arriving Monday so I’ll be able to do a bit more testing and see exactly what’s going on with the lid thermometer at that point.

 

1 minute ago, Boater said:

@flynnShort version, I don't worry about the specifics.  The grill will do a consistent job just based on the dome temp.  


I’ve been using it and it hasn’t steered me too wrong, but a chicken breast recipe that was supposed to take a full hour at 225 only took me 40 minutes to bring to safe temp so I worry that kind of inconsistency on a longer cook could ruin a better piece of meat than chicken.

I’m probably overthinking all of this, but I’m pretty new and just running off of a small sample of cooks.

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5 hours ago, flynn said:

I’ve been using it and it hasn’t steered me too wrong, but a chicken breast recipe that was supposed to take a full hour at 225 only took me 40 minutes

 

That recipe for a kamado or an oven?  225 in a kamado isn't the same as in an oven, or a gas, charcoal or pellet grill, because of the convection.  If that recipe was supposed to be in a kamado, that's not the issue.  But translating recipes from other cooking methods will make a difference, especially the first time on the kamado. And again, I use it as an index - so next time I'd do that recipe, I'd expect those to be done in 40 minutes (give or take). 

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Finally got my Signals in. My lid thermometer is almost 100 degrees low compared to the Signals probe clipped above the grill grate towards the back of the cooking area. 
 

On the plus side, made some tasty burgers tonight by adding a chunk of Cherry in with the charcoal.

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