Question with Chimney Vent

sjm1027 · December 2016

I understand the bottom vent lets air in thru the coals, more air more heat... The top chimney vent is my question. Typically that is to keep the flow steady I would guess. If your using smoking chips would you want to close the vent a little so the smoke would stay in the dome? What is the best way to understand this with cooking and smoking?

JustineCaseyFeldown · December 2016

You can't let out more smoke, or keep in more smoke, than the lower vent lets in

turn on your garden hose

if you want, you can control the amount of water by opening the tap or shutting it

or you can go to the far end and control it with the nozzle

on the BGe it is a belt and suspenders deal. Either one works by itself. Together it's a little insurance

but if you let out more smoke, you are allowing more draft. That will always raise temps

only when choking back a hot fire will you restrict outflow. But eventually the egg hits stasis.

Conversely, opening the lower vent will also raise temps, until the top chokes it back

stack effect can impact this to some extent. Whoch means you can find examples that will contradict. But eventually, one of your vents will out-muscle the other.

Air is essentially liquid. Can't put more into the egg than fits. And can't let out any without letting an equal amount in to replace it

DieselkW · August 2017

I'm convinced that there is a difference between controlling flow with the bottom vent, and controlling flow with the daisy wheel.

My dealer advised that I try to "match" the flow rate - meaning bottom vent open 2 square inches then the top vent should be open two square inches. Then why have two different shapes? If the top vent slid open the same way the bottom vent does, 1" wide by 3" long, it would be easy to match vent openings.

I guess I need to do things the hard way sometimes.

I can "fine tune" my smoking temp by a more open bottom vent and a barely cracked daisy wheel. This allows a bit more air to circulate inside the ash box below the fire to make sure my fire doesn't go out, but keeps the air flow choked enough to stay below 250º dome. This is critical for me when overnight smoking without a DigiQ. Too many ruined butts by waking up to a fire that went out. I'd rather smoke at 250 than have the fire go out at 200.

My fires tend to put themselves out at <225º dome, credit card opening bottom vent and barely cracked daisy. I think the problem is as the available fuel dwindles down, it requires more air to maintain temp.

To avoid this, I use the top vent to choke air flow and keep the temp low, but a more open bottom vent to allow some air to swirl around the ash chamber keeping the fire going. Works for me, might not be the same for a different Egg.

I've tested my Egg after a cook with a closed bottom vent and a wide open daisy, the holes open, sliding the wheel over. The fire won't go out until it runs out of fuel. Obviously, it's drafting down, right?

So, I can skin this cat with either top or bottom vent or combination of both. I know there's a contingent of cooks reading this forum that only use the top vent to control temperature.

Fred19Flintstone · August 2017

The garden hose analogy is right on. It's physics and you can't change that. Ultimately it's more freedom. If you like to fiddle with the bottom vent or top vent or both at the same time, the results are the same. It's all about air flow.

GrillSgt · August 2017

Chips? CHIPS?! We don't use no stinkin' chips around here.

bigegger · August 2017

I've come up with different upper and lower vent settings for the same temperature ranges ive been cooking with which are 250º- 275º, 300º-350º and then the hotter ranges which I usually need for only a few minutes (steaks and pizza) which the chimney top is off and bottom vent is fully open.
But I honestly think the settings depend on the type and size profile of the lump charcoal being used. And I also think settings will vary on how much of the charcoal is initially lit upon fire up before the dome is closed.
So every time I fire up the BGE and warm it up to temp for low and slow cooks, i guess a vent opening setting and adjust as necessary as I look at the dome temp indicator.
The many suggestions above are real good baselines to start off with.

SmokingPiney · August 2017

The bottom vent is my primary temp controller. After tons of cooks, I have a sight picture as to where I want to set it. For most hot and fast cooks, I don't really bother with the daisy wheel and will leave it open, or about halfway closed depending on how the coals are burning.

The daisy wheel does come into play for low and slow cooks. I have a sight picture for the bottom vent, but I'll use the daisy wheel to fine tune the temp.

Question with Chimney Vent

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