Cost comparison and heat/ash

[Polarbear777]

For a long time now, I've been thinking that more fillers in charcoal is bad. Of course more fillers (KBB) means the briqs hold together better. Again, on the other hand, if you have more fillers you get more ash buildup, which can be a problem for some rigs if ash blocks airflow on long cooks. Also with more fillers, you get less heat per unit charcoal.

I dug up some old cooks from when I did low and slow with KBB and switched to Stubbs (sadly gone now, but representative of hardwood briqs). Looked up the current _regular_ prices and did a comparison of cost per cook time, which is basically cost/heat. Here are the results, I compensated for dust loss in the bag (I see more dust loss in hardwood bags than in KBB, presumably due to the binders/fillers).

All run on the PK360 with a full charcoal basket (my custom basket), all lit and run the same way with a fan controller tending the fire. I do assume here that the density of coals is the same, but didn't measure that, so I'm assuming a full basket (volume) is equivalent mass.


Interestingly the cost/heat is the same. So this means for low and slow you can use whatever charcoal you want, so long as ash isn't a problem for your cooker. Of course if you get anything on sale, that would win.

Also, the last column shows a calibration run with no water in the cooker, so you can see that having a heat sink, like water or food, has a big effect on how long your coals last (and so does ambient temp, to a lesser degree etc)

[Polarbear777]

Also means that if you need or want less ash, you shouldn’t feel bad about paying more because you really aren’t.

[au4stree]

Polarbear777, great write up! Thanks for posting.

[Mr. Bones]

Very interestin an useful data, thanks!

[HawkerXP]

Interesting.

[fzxdoc]

I love this sort of analysis. Thanks so much, Polarbear777 . Very interesting reading.

I'm more concerned about ash in my PBC because it blocks the underside of the charcoal basket during long cooks. I've toyed with the idea of raising the basket an inch or so to see if that makes a difference.

My WSCGC seems impervious to ash buildup. It just keeps on cooking with its rock solid temps. Makes me wonder why I want to add the Fireboard fan controller cable and a Pit Viper fan to it. Just because I can, I guess.

Kathryn

[fzxdoc]

Polarbear777 , I don't bother with ash in kettle mode unless I've got the SnS going. Then I keep an eye on it. In kamado mode it's great that ash buildup doesn't seem to be an issue with the WSCGC.

[Dadof3Illinois]

If I KBB in my 26” kettle with the SnS XL it starts clogging bad after about 5 hours. Weber does awesome.
I have the same issues in the PBC with KBB but I like the flavor profile KBB gives the food for some reason.

[Polarbear777]

You can run a kettle pretty much continuously if you remove or cover the food, shove the coals around and run the ash sweepers.

[CaptainMike]

Great post Triple7PB!

[RobertC]

Thanks. Very nice.

It's (surprisingly?) hard to find the heat content of a briquette. KBB briquettes weigh about 25 g each (so 40 to a kg, which is roughly what many of us use to start in a chimney). About 20% of a KBB briquette ends up as ash, so the burnable part is about 20 g.

[Polarbear777]

Yeah, I'm sort of guessing based on how long they last at a fixed bake temp.

[RobertC]

Polarbear777 A rule of thumb appears to be that pure charcoal contains something like 25 to 30 kilojoules per kilogram, so a pound of briquettes that's 20% ash is right in the ballpark of 10 kJ. So if you're burning a pound an hour of KBB, it releases energy at a rate of about 2.75 kW, give or take.

[JeffJ]

Very interesting write up.

Thank you. Fortunately, our local Lowe's has Stubbs at a good price.

[Polarbear777]

My Lowe's used to but none of the local lowe's had restocked since last summer. Discontinued everywhere I look now. Some may still have some left.

[Troutman]

Just get a bigger boat