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Jun 7, 2009 05:12 PM

Best way to control charcoal grill temperature

I'm starting to play with my new charcoal grill and I had a question about controlling the grill's temperature. I have the two vents--one on top and one on the bottom. Which vent should be used to control the temperature? Top or bottom, or both? I know if I want the grill hotter, I should open the vents, and vice versa. Thanks!

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  1. yep, bottom vent has more to do with it. Control the air and you will control the fire and temperature. Normally good to start with less fuel if you want lower temps and more fuel for higher temps.

    With a Weber smoker for instance you control the temps with the bottom three air vents, load it full of briguets and control the temp with air flow. With this method you can have it run 20 hours at 250 degrees. You can somewhat do the same thing with other types of units.

    2 Replies
    1. re: duck833

      I have the Weber kettle grill. So I should just leave the top vents open and open/close the bottom vents to really control the temperature?

      1. re: bla4free

        No, adjust them both. I tend to throw wood on the charcoal so, I damp the top vent to keep the smoke in a lot more now. For straight charcoal, balance the top and bottom vents unless you are cooking with wood for smoke or dealing with high winds.

    2. I have two old Weber kettle grills. The older is probably close to ten years old. The newer maybe five. The bottom vents are completely rusted out and permanently open. I keep that grill simply as a holding counter for the newer one. Occasionally I will use it if all I want to do is blast the heat out. The younger one is starting to lose its bottom vents as well.

      Any recs. out there?

      12 Replies
      1. re: VivreManger

        You can order replacement vent dampers from weber. They are riveted on. you will have to drill the old one out & pop rivet it back on. If the bowl is rusting then you can pickup a donor bowl on craigslist for $10-25.

        If you just have a big hole now you can use sheet magnet material to cover/uncover the air hole as needed.

        1. re: jiarby

          Maybe some models are different, but on mine which is the 22.5 inch kettle with the three bottom vents and an ash catcher underneath - also about 10 years old, the bottom vent isn't riveted on.

          I just replaced my old rusted out assembly with a new weber replacement "One-Touch Cleaning System" ~$15 in the USA.

          In order to get the old one out, I used a hack saw to cut off the handle on both ends of the nut, then popped it out by hitting it with a hammer from the bottom. The new assembly is easily put together with just a thumb screw; no riveting!

        2. re: VivreManger

          I've owned a few Weber's over the years and currently have 2 kettles and a WSM smoker. I live in Florida where the humidity and salt content in the air is high. I use one of my grills at least 3 times a week.

          I've never had a vent rust out. How could that be happening to your two grills which are, by Weber standards, relatively young?

          1. re: bkhuna

            It's more a function of corrosion as a result of the high acid content of the ash. If you clean the bowl of your grill with some regularity you'll avoid the "corroding shut" phenomenon that happens when metal and acid ash and moisture interact.

            1. re: bkhuna

              More than likely, the grills were left uncovered and allowed to collect rainwater which, when mixed with the ash in the bottom of the grill, will greatly increase how fast the grill will rust out.

              The solution is to cover the grill with a waterproof or at least water resistant cover.

            2. re: VivreManger

              FWIW, a buddy of mine has one that's 7-8 years old and had similar problems with the vents, etc. He was looking at buying a new smoker or grill. I think he decided on getting a WSM but keeping the old one and limping along for grilling. He ended up calling Weber to get parts ordered. Turns out that it had a 10-yr warranty and they provided everything gratis.

              1. re: ted

                I keep the bottom vents on my Weber kettle open at all times. The most I'll ever adjust them is to maybe close them halfway. I use the top vent for controlling temperature, and it seems to do the trick pretty well.

                1. re: jacobp

                  Well, I bought a grate thermometer to put on the grill grate so I could practice controlling the temperature. I was trying to get the temperature to the medium temp of about 325 or so and I was never able to get it there. I tried adjusting both top and bottom vents. Which vents "should" work the best?

                  My second question is how long should I let the charcoals sit in the grill before I start cooking? I use a chimney starter and they probably stay in there for about 10-15 minutes or so. Then I dump the coals into the grill. Should I let them sit for a while in the grill before cooking?

                  And my third question is should I start with brand new charcoals every time, or is it okay to use the old ones in there that didn't burn up completely?

                  1. re: bla4free

                    Once I dump the charcoal, I let it sit with the cooking grate on it (lid closed) for about 10-15 minutes to let the grate pre-heat. Then I oil the grate and let that sit a few minutes before cooking.

                    1. re: Philly Ray

                      Thanks. I think my problem is I'm rushing the grill. Also, when using the chimney starter, how long should I let the coals heat up? Some sites say let them ash over, others say only put a few coals in there and lay them on top of fresh coals in the grill. I just want a good way to start grilling at about 350F or so.

                      1. re: bla4free

                        well, it all depends on your chimney and what sort of charcoal you're using. if you're using briquets, i'd suggest having a little ash on them before you pour them onto the grill. As far as controlling temperature, how you arrange the coals is as important as whether you leave the vents open or not. I try to pile half or a third on one side for high heat for searing and use the other half not piled as high for slower, longer grilling

                    2. re: bla4free

                      Concerning how long to let your coals sit in the chimney before you dump them into your grill, you'll want to wait at least until the top coals have caught but not longer than the top coals have ashed over. The type of cook and the required heat will determine when exactly you should dump the coals. However, with that said, we're not making a bomb. It's just cooking. It's not that big of a deal. All it is is a balancing act between making sure the coals are hot enough for what you need while not being too far along as to burn up before you're done cooking.

                      Concerning when to start cooking after you've dumped the coals in the grill, the answer is . . . it depends. If you're cooking on low heat such as smoking something on low heat for a long time, you'll want to start cooking immediately as it's easier to increase the air temperature in your cooker than it is to lower the air temperature. However, if you're wanting to sear a piece of meat, then you'll want to allow the coals to heat the grate for five or ten minutes before you start cooking. I wouldn't wait too long though as your charcoal will begin to burn out unless you've prepped your grill with unlit coals beforehand that will catch as time goes on.

                      Grilling with two zones is a very easy way to grill. As others have described, you simply pour your coals on one side of the grill which will give you a hot side and a cooler side (and everything in between). This allows you to move food around to where it needs to be as there will always be hot spots and cool spots and not all the food on the grill (if there are multiple pieces) will always cook evenly. Don't feel like where you put the food down is where it has to stay. Move your food around to where it needs to be. A two zone setup will help you do this.

                      Practice and learning from experience will quickly help you become very comfortable in these areas and all things grilling.

              2. I keep it kind of simple. I just make a heap on one side of the weber. Charcoal almost touching the grill. Sometimes I have to push on the grill to shove the charcoal down a little. Then I light it with a brush burner, 250,000 btu's of roaring loud flame. This will get the charcoal going in 3-4 minutes, all the surface stuff. Then I put on the lid and give it 3-4 minutes or so to build up more heat.

                Meat goes right on the grill into the inferno, maybe 40 seconds or so and I turn 45 degrees for good grill marks. After 1 1/2 minutes or so I turn and repeat the grill marks. Then I move meat to the overside of the grill away from my flaming charcoal heap. Put the lid on and pull when steaks are 119-120 internal temperature. Absolutely works every time!!!!

                When the cooking is done I shut down the vents and save the charcoal for the next cremation.


                1. Keep the top vent wide open until you're done cooking, then close it to snuff out the fire and conserve the charcoal. Use the bottom vent for fire control: the more open they are, the hotter the fire will be. The reason you don't want to close the top vents while cooking is because doing so smothers the fire, and a smoldering fire is a dirty fire. Food cooked using a dirty fire will taste bitter and burnt. That's the creosote you're tasting, and creosote is a product of a dirty, smoldering fire.

                  What you really want is a relatively small, hot fire. Control the size of the fire by controlling the amount of fresh air (oxygen) getting the fire, not by restricting the fire's ability to 'breathe'.

                  Think of a charcoal bbq as if it were a car - you don't slow down a car by plugging the exhaust pipe, you do it by reducing the flow of air to the engine. And you speed up the car by increasing the flow of air, too. A car is at it's most efficient when the exhaust system is unrestricted...just like a bbq.

                  5 Replies
                  1. re: ricepad

                    Ricepad; This is the best explanation I have ever read on the matter of vents. Thank you for your guidance on this, as you have saved me from hours of trial and error. Most of all you have saved me from ruining my food.

                    1. re: ricepad

                      Very good explanation, but this works for typical grills. On my BGE, if I had the top wide open, and the bottom vent opened a sliver, it'd be well above 250. You can get a good draft with both the top and bottom vents opened up just a sliver as well. For 225 smoking, the top vent is opened so little, you'd think it's closed - but it's just barely cracked open.

                      1. re: ricepad

                        Standing Ovation!!!!!!!

                        The bottom vents are your accelerator.....the top... the exhaust pipe!!

                        1. re: ricepad

                          If you're using a kettle this is the man you want to listen to. His advice is accurate and concise. Memorize it and move on. BTW if you decide to take up smoking, spend some time at and learn the minion method of fire building. It will save you a lot of wasted meat. Enjoy your grill.

                        2. Last time I did an indirect (coals on side) on a Weber Kettle (Performer) with all vents wide open the top vent varied from 290-320 which is a nice heat for most anything. Maybe chicken you may want a little higher but why bother making the kettle do what it doesn't want to do? I just let it hum along and I adjust my time expectations.