Temp control: adjust top or bottom vents?


 
KevinInStL said:
Wait, are you saying that you can add one of the stock Weber ash catchers to a basic kettle? I didn't even know that was an option!
Click to expand...

Yep... that's exactly what I did. I can't remember (exactly) where I got the parts as it was at least 5 or 6 years ago when I did the upgrade. But a quick google returned the following this link ([url]https://www.ereplacementparts.com/weber-charcoal-grill-parts-c-193079_193086.html)[/URL], which sounds familiar. Another website that looks promising is this one ([url]https://www.grillparts.com/weber/weber-charcoal-grill-parts.asp)[/URL].

Like I said, my goal wasn't to turn my kettle into a better smoker but simply to improve the ash-management system.
 
Yes, the improved ash catcher can be done for not a lot of money.
Until I got a WSM I did a lot of smoking on my kettle, many excellent feasts from the kettle, butts smoked nicely, I have a friend that uses his 26 with a slow and sear and says he has had excellent results. I’ve used a “Tip-top” airflow attachment on the kettle as well, with fine results. Is it as easily manageable as a WSM? Not necessarily but, with practice you can do almost anything on almost anything.
What I am trying to say is learn what you can do on the kettle, you will not be disappointed after you really find out what it will do!
Get the ash catcher, turn the kettle over and in fifteen minutes, you will be ready to go!
The improved ash management system will not convert your kettle into a smoker but, it will get you one more tool in the arsenal until you get one!
 
Last edited:
I think it is important to note that meathead's article is about controlling temperature. But he should really flesh it out further because a cook is actually controlling three variables with the vents: temperature, smoke and gases. Controlling temperature is the most important but refinement in smoking requires knowing the difference between the three.
 
From the Summit Charcoal Grill manual:

"A major component in charcoal grilling is air. The more air allowed into the grill, the hotter the fire will grow (to a point) causing the charcoal to burn much faster. The bowl vent on the bottom of the grill should be open while grilling or in the smoke position while smoking. The top damper is used to control the temperature within the grill; however, should never be completely closed."

From a weber.com blog post on smoking in a charcoal grill:

"The grill vents control the airflow. The more air flowing into the grill, the hotter the fire will grow and the more frequently you will have to replenish it. To minimize that, keep the lid closed as much as possible, but the vents on the bottom of the grill should (almost always) be left open whenever you are cooking. To slow the rate of your fire’s burn, close the top vent as much as three-quarters of the way."
 
Well I'll have to give that a try Chris. With my performer with the one touch getting down far enough to see where my lower vents are positioned is getting harder in my old age. Using the top vent would make life easier. Also I wouldn't be opening the lid to see where the vents are positioned and letting all the heat out.
 
I'm going to have to disagree with the manual. Look at the gateways. They control temps with the bottom vents. The pipes extend to the top of the unit so you dont have to bend down.
 
Thanks Donna, Thant’s the way I’ve thought about it. Of course some adjustment of the outflow is part of it but, primary heat adjustment on the bottom.
 
So three pages in and there's still not a consensus on the answer?

I've been trying to think through the fluid dynamics of it and how the air would flow (thinking of both volume and velocity). Fresh air will only enter into the grill as fast as the old air leaves. So if you close down the top vents, you reduce the volume of air leaving the grill, which in turns reduces the volume of fresh air entering the grill. Closing the top vents would also decrease the velocity of the air movement through the grill (old air is in there longer). Leaving the top vents open, you reduce the restrictions on air leaving. If you then close the bottom vents down, the volume entering will want to stay the same as the volume leaving, so the velocity of the air movement will increase as you close down the bottom. So if I'm thinking of it correctly, adjusting the top vents will have a bigger effect on the volume of air movement through the grill, whereas adjusting the bottom vents will have a bigger effect on the velocity of air movement in the grill.

Of course, I could be way off base as I started trying to translate fluid flow through a cylinder into fluid flow through a kettle. And ended up looking at it more like an equilibrium problem.
 
Last edited:
To me, it makes more sense to control combustion by controlling airflow into the cooker at the bottom where the fire is located, then allowing exhaust gases to freely leave the cooker via a top vent. For Weber to say the opposite in kettle grill instructions has more to do, I think, with the ease of seeing and adjusting the lid vent vs. fiddling with the One-Touch sweeper at the bottom of the charcoal bowl.
 
The fluid dynamics of it is way over my head. I know at one time Harry Soo was advocating using the top to control temp. I think that's mainly how they control temps on big Jambo Pits. My thinking is there will be more gas coming out than what is coming in just because you are going to have gas created by the combustion that has to leave. Also the air as it is heated needs to expand. I don't think you'll see a real consensus on this. It's also not like the air can only go one speed in or out. It's going to speed up the air somewhat if you constrict airflow somewhat, right? Kind of like a garden hose.
 
Chris Allingham said:
To me, it makes more sense to control combustion by controlling airflow into the cooker at the bottom where the fire is located, then allowing exhaust gases to freely leave the cooker via a top vent. For Weber to say the opposite in kettle grill instructions has more to do, I think, with the ease of seeing and adjusting the lid vent vs. fiddling with the One-Touch sweeper at the bottom of the charcoal bowl.
Click to expand...

I fully agree with the physics behind this thought pattern Chris! Restrict intake which will slow (reduce) the heat.
In a very few instances the use of top vent to make minor adjustments is fine but, marking the catcher or learning where to close things down. It’s really about learning how to control a “Combustion Chamber”, reduce intake (choke) = slow fire...increase intake (open throttle) increase fire.
Sorry to feel like a complete idiot but, this is stuff I learned when I did the first turkey I ever did on a Weber, 38 years ago.
I think there are some threads that I should just leave alone.
That said, it’s not as complex as “WE” seem to make it. Put food on grill, if it looks like it’s going too fast, choke it back, if it’s rolling along, just RELAX, the end product will be just fine.
Some of the concern over minutiae is just silly. If you’re in competition, that’s a different issue which you can only learn through trial by fire, no pun intended but, surely applicable.
 
Chris Allingham said:
To me, it makes more sense to control combustion by controlling airflow into the cooker at the bottom where the fire is located, then allowing exhaust gases to freely leave the cooker via a top vent. For Weber to say the opposite in kettle grill instructions has more to do, I think, with the ease of seeing and adjusting the lid vent vs. fiddling with the One-Touch sweeper at the bottom of the charcoal bowl.
Click to expand...

Bingo. Manuals are written for the casual user and controlling temp with the top vent is a very simple-to-understand instruction and frankly, won't effect the outcome of a casual cook one way or the other. Imagine a manual for a product as ubiquitous as a Weber kettle that gets into fluid dynamics and the importance of balancing the temp, smoke and gasses. That's what forums are for!!

Jeff
 
Yea I dunno. You have more intake than outtake and on a WSM that would be 3/1 and on a kettle with a one touch maybe 4-5/1.
Makes more sense to adjust the intake, but I guess that comes down to the individual and what your using now.
My first kettle was a 3 vent daisy wheel, and like my WSM"s I'm just used to dealing with the intakes.
I don't think we need a real consensus on this, just whatever works for you.

Tim
 
I always kept the top vents wide open and controlled the temp with the bottom ones with my WSM's.
With my current smoker the WSC, I use both top and bottom vents. Bottom vent stays at the smoke setting and fine tune with the top vent. It's a different animal, much less air flow than the WSM.
 
Last edited:
You must log in or register to reply here.

 

Back
Top