Ashes to help control coal base overheats?

[Chasdev]

I was watching a YouTube cooking show where they were cooking over open coals in a long rectangular cooker.
Must have had a few hundred lbs of lump which they dumped on a previous cook's embers.
They stirred the new in with the old and the new started to flame up but before they placed the meat over the coals they spread a layer of ashes over the entire surface of the charcoal.
This gives me the idea that when coal base gets built up and I can't add another stick for a while or the temps might run away, I could pour some ashes over the coal base to calm it down enough to allow more wood to be introduced.

 

[Redicans]

Interesting idea, never seen it done. Lets see some pics if you try it. Curious how it would work.

 

[SmokeRing0909]

So basically feeding the oxygen poor bed of the fire? Would that keep the bed going and hot? I’m new to this but enjoy physics

 

[Chasdev]

My impression is that they were slowing the rate of increase of heat and flames from the new coals.
They were cooking a dozen whole chickens at a time in multiple rotating baskets, gear mounted to the end of a shaft driven by another mechanism.
The potential for flare ups was real, coating the bed with ashes delayed/restricted 02 from reaching the coals (slowing the rate of heat increase from the new lumps).

 

[crankybuzzard]

They were basically banking the fire. The ashes will slow the oxygen rate to the flames but the embers would still smolder. If you need more heat, you stir it around a bit or add a little wood, getting too hot, add some ash to the hot zones.

The fire itself goes out when the oxygen level drops, but there will still be smoldering of the coals and embers. Think about when people cook goats, sheep, or barbacoa in a pit dug into the ground and then they cover the pit with sheet metal and dirt. When they open it up 8-12 hours later, it's still hot and has some viable coals left.

 

[Chasdev]

Final report on ash for temp management..it works.
Took longer than I expected, around 10 minutes, but lowered the cook chamber temps so much I had to uncover the coals and add more wood to get the fire back up to temp.