Interesting... Temp control

[bosco]

So I usually do 3 turns up top and half open bottom for 350/375.  

Ckreef posted today that he has his dome top shut way more than that.  So today I am experimenting a bit.  

I opened it to the normal settings for 375.   Once it hit my temp I left the bottom half open and dialled the top down to half open. 

So I turned the top damper down and my temp is now hovering around 300.  After about 30 min.  

I will need to play with this a bit to see if I can close stuff down and save on fuel 

[Bruce Pearson]

 I don't know who said it but i read that the top vent is the key to adjusting temp.

[bosco]

I'm sticking with what works.  Forget it lol

[Stile88]

18 minutes ago, bosco said:

I'm sticking with what works.  Forget it lol

Lol mine is almost like your settings but i am finding i am using as much if not more fuel then my egg 

I did try cks trick about taking out guru plug and had my dial open the half moon and got to 400 and stayed there with top vent 3.5 

[MacKenzie]

Stile, remember you have much more mass to heat up but once it's up to temp. I bet you'd use less lump to keep it at that temp.:)

[Stile88]

6 minutes ago, MacKenzie said:

Stile, remember you have much more mass to heat up but once it's up to temp. I bet you'd use less lump to keep it at that temp.:)

Yea your right on that Mac it just seems like i do 

[tinyfish]

For 350/375f I would have the top 1 -1.5 turns open and bottom vent (old single dial) a touch more then half open. 

[Aussie Ora]

I seems to me that since these awesome Grills are hand made its a bit different for everyone but what works in the end is the go. I've done two cooks both times I spun the top vent 4 turns opened the left vent. I have the dual model fully until 75 short then spun the top right back and gave it 2 turns and adjusted the bottom right vent 3 notches and the left vent to the third largest hole. And it's has sat perfectly just under 400

Outback Kamado Bar and Grill

[ckreef]

I've made this post once before but I can't seem to find it so I'll give it another go...............
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When talking about md high heat (350*-550*) there are two basic ways to manage your coals. A) hot fire, large bed of coals. B)cooler fire, small bed of coals. Each method has it's pro's and con's.
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A) hot fire, large bed of coals. Mainly useful for direct grilling and searing. (I like this method for rotisserie)
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Pro's - coals covers a larger area of the grill so more protein sits directly above the coals. Faster to come to temperature.
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Con's - uses more fuel. Can cause a hot zone especially if doing an indirect cook.
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This requires a larger top vent opening. A lot of heat will be wasted going out the top vent which will in turn require a larger bottom vent opening. The end result is burning more lump and having a larger bed of coals.
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cooler fire, smaller bed of coals. Especially useful for indirect cooking and baking.
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Pro's - burns less lump to maintain a given temperature. More even heat distribution especially when doing an indirect cook.
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Con's - takes longer to get to temperature. Smaller bed of coals not good if direct grilling a large amount of protein.
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Once near target temperature the top vent can be set with a smaller opening. In turn the bottom vent can be set with a smaller opening. With a smaller top vent opening more heat is trapped inside the kamado so a smaller fire is needed to maintain a given temperature. This will take longer to stabilize at a given temperature.
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Most of my cooks are md high heat. Both methods will obtain a stable temperature. Once I decide what I'm cooking I choose the best method for that particular cook. Unless direct grilling or rotisserie I usually use a smaller top vent opening as it conserves fuel and I go through a fair amount of lump on a weekly basis.

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[Bruce Pearson]

Thanks Charles nice to know

[wilburpan]

Hi Bosco,

I have a slightly different approach to medium temperature cooks. I’m assuming that these are indirect cooks done at a higher temperature, such as cooking poultry.

In general, I’ll light a good portion of the basket of charcoal to start. But I’ve found that smaller vent settings than the ones you’re using are good for these 300-400ºF range cooks. I’ll typically have the bottom vent open about 1/4-1/3, and the top vent open 2-3 turns.

I think that overall, it’s a good strategy to use the minimal possible setting for the bottom vent, and to use the top vent for fine tuning. I think about the bottom vent as a choke point to limit the total amount of air that can enter the grill and feed the fire. This also helps with situations where you have a windy day that will naturally cause more of a vent draw at the top vent, leading to unstable temps.

[bosco]

Very interesting day today in my quest for perfecting my temp control.

Opened the top vent 3.5 turns and bottom vent opened half way and got to 375 in about 14 min.  So I figured that I would see how I can monitor the theme a bit better.  

I turned the top vent down 2.5 turns and the bottom to 1/4 open.  It staid at 375....

hmmm???? could Ckreef be onto something here?

dialled the top vent down to 1/2 turn open and closed the bottom down to 1/8 and it lowered down to maybe 365

So closed the top to 1/8 open and left the bottom 1/8 open and it locked in at 350.  

Now everything that I have known is out the window.... I am seeing major fuel savings in my future if I can replicate this 

[tony b]

Do tell? I will look forward to more posts and data points. 

[Syzygies]

19 minutes ago, bosco said:

I am seeing major fuel savings in my future if I can replicate this 

Dennis is quite eloquent about the purpose of the basket splitter: Make sure all air passing through the KK passes directly through the charcoal. I'm also reminded of the design of cabin wood stoves like the Vigilant stove.

If fuel savings is a primary goal, then one wants to let in enough oxygen to generate desired heat, with absolutely no more airflow than necessary. A rock and a hard place, for without airflow there's no new oxygen for the charcoal, but wasted airflow is expelling wasted heat.

Using a BBQGuru for low and slow naturally adopts a conservation protocol. I hadn't thought explicitly about conservation for higher temps, but I'm surely thinking that way now that I'm hooked on KK coffee charcoal.

A companion goal is moist meat. Excess airflow is unwanted drying. One gets the moistest meat with a full cooker, but for a given load, one also wants to minimize airflow.

So, yes, thank you for directing our attention to this, and kudos for spelling out the protocol to achieve this. I've sort of been doing this unconsciously, but it always helps to actually think about it.

[bosco]

Locked solid at 350 with 1/8 opening on top and bottom.  Very interesting.  It is like finding a sweet spot

So for my next test, I will run my KK how I normally do to get it to temp.  The dial it back once it is heat soaked again.  Do it before fully heat soaked, I think that the temp will drop drastically.  

Heat soak is the key.  

[Pequod]

Recovering fluid dynamicist here, although it's been a very long time since I worked as one. But when I did work as one it was related to combustion chambers of things that fly to great altitudes.

Here goes: to hold a steady temp means you're at equilibrium. Energy in equals energy out. Energy in is coming from two sources: ambient air via the lower vent and that being released by combustion of fuel.  Energy out is the hot air leaving the chamber and heat loss through the walls. Set the two equal to each other for equilibrium.

Energy in air leaving the top vent + Energy lost through walls  = Energy due to combustion + Energy of ambient air in. 

Any combination of settings that keeps that in balance will work. ckreef keeps the air leaving low and combustion energy low, thus saving fuel. Other settings work too, but are less efficient. 

Sorry for geeking out. 

Edited August 30, 2016 by HalfSmoke

[ckreef]

@bosco I knew it was just a matter of time before you figured this out There are two ways to run it. Vents open for searing and direct cooking, vents closed down for most everything else. And no worries this is a repeatable situation, you just have to perfect your process and you'll nail it every time. Coming from an Akorn I almost had to figure it out from scratch and this is what I figured out.

I usually fire my KK's up wide open until I get really close to final temp. I then close the vents down. Temp falls but will always rebound really close to where I want it then I know it's heat soaked and ready. There is enough thermal mass even in my 16.5" for this to work.

. @Syzygies really good explanation of heat and moisture retention. Cooking at md/hi heat with the vents closed down really does retain more moisture (doesn't even seem possible

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[5698k]

Geek is good!


Rob

[Pequod]

Just now, 5698k said:

Geek is good!


Rob

Heck yeah!

[ckreef]

 

Any combination of settings that keeps that in balance will work. ckreef keeps the air leaving low and combustion energy low, thus saving fuel. Other settings work too, but are less efficient. 

Sorry for geeking out. 

I usually don't go for the geeking out posts but that last paragraph sums it up perfectly.


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