Does Use of an ATC affect top vent position?


 
N

NickB

TVWBB Member
Greetings Learned Forum:

After reading many posts and recipes from this site, the conventional wisdom seems to be "always leave the top vent fully open." In fact, I have not found a single recommendation to the contrary.

But by adding an ATC into the equation, does this change things? Are there instances where partially closing the top vent is helpful? Or is fiddling with the top vent the "third rail" of good BBQ? Any thoughts and experiences are greatly sppreciated. Thank you.

NickB
 
I use a homebrew ATC (HeaterMeter) and I close the top vent on my Big Green Egg almost completely. I found that the more open the top was, the less control the I had over the temperature. With the top bit open the temperature would overshoot a couple of degrees then take a very long time to come back to temperature. With the top almost closed, the temperature just rocks back and forth on either side of the setpoint.

I've also had one incidence of the temperature getting to high and the fan not running at all for upwards of an hour. If the airflow is not restricted, it seems to have a tendency to draft through the fan due to convection. My fan doesn't have any damper in it or anything though so that could be the cause.
 
That makes sense, Ed. Especially the part about the inherent leakage of the WSM. If it were completely airtight, opening up the top vent to some extent would be required. But since it is far from airtight, the blower will provide more than enough pressure to vent the system through all the little openings.

Well, my chance to try it is weekend after next. I will be doing my first pulled pork, and it will be an overnight smoke. My Auber should arrive early next week. I am psyched to play with it.

NickB
 
Originally posted by Stefan B:
Anytime i use my DigiQ i always leave the top vent wide open and all lower vents 100% closed.
Click to expand...

Ditto, and temp control is not a problem. I would be more concerned about over all sealing of the mid section (out of round condition). You can use a "snake" of aluminum foil pressed in place to trouble shoot that. Wouldn't worry about the door unless its real bad. With ATC you want the fan to provide ALL the air entering the cooker. You want the chimney (top vent) wide open though for good draft IMHO.
 
Just to back-track a bit, i do sometimes close down the top vent a little if it's really wind out.
 
The manufacturers all seem to agree that the top vents should be almost completely closed. That's what I do on my BGE and it seems to work very well.

Bill
 
I have a DIY controller and I leave the top vent open 100%. I only get one to two degrees overshoot. I would think the reason the vent has to be closed is due to air leakage at the fan or using a fan that is too powerful IMHO.
 
Agree with AJ and have to say you've done a great job in a home built if your OS is 2 deg - Nice! That's probably closer than any home oven. Pretty sure these controllers for smokers are capable of tighter temp controls than typical home kitchen appliances. Interesting since a plus or minus of 25 degrees probably doesn't make a difference IMHO. Not knocking it at all just making a point.

The Guru unit I have certainly has a fan that has more CFM than required (10 CFM) for my 18.5 WSM. But their fan unit has a choke to control that so you don't need to rely on the top vent. Probably why they tell you to just leave the top vent open.
 
Originally posted by r benash:
Agree with AJ and have to say you've done a great job in a home built if your OS is 2 deg - Nice! That's probably closer than any home oven. Pretty sure these controllers for smokers are capable of tighter temp controls than typical home kitchen appliances. Interesting since a plus or minus of 25 degrees probably doesn't make a difference IMHO. Not knocking it at all just making a point.
Click to expand...

Ray,

You know the saying "It's better to be lucky than good."

That's pretty much what happened when I ended up with a two degree overshoot. I attribute part of that to my design but the lucky part goes to the fan I selected from my parts bin.

I'll take lucky any day. Just wish it would be one of those few days that I play the lottery...
 
I have a DigiQ2 Temp Controller, and I have it closed down to 1/2 open, or closed, whichever you want to call it. My WMS was overshooting by 30+ degrees with the top vent wide open, so I started closing it down and it took me about an hour or more to get the DigiQ to "stabilize" on my target temp. I was getting quite a bit of smoke of of the side door and at the bottom above the fuel seam. So, yes, it does leak. One smoke I was getting smoke out from around the top temperature guage on the WMS. Experiment and find out what your unit likes I guess is all we can do.
 
A.J. - I would rather think you skillfully selected the correct components and have come up with superior design
icon_wink.gif


George, just curious if you experimented with closing down the fan port using the slide first if you would have reached the same result (with the top vent full open).

Not suggesting one way is right or wrong at all but just thinking that the root issue may be with the Guru fan putting out full 10CFM that your problem is being resolved by cutting down the total draft/flow by 50%. This can be accomplished I believe by either cutting the input or damping the stack flow IMHO.

In the end you solved your problem and that's all that matters.
 
The Day I was getting a high over-shoot on my Weber Mountain Smoker, using a DigiQ 2 it was very windy. Unlike some people, my wife and I LOVE a LOT of smoke flavor and I put a lot of hardwood in. Since that one instance of over-shoot, I have had no problems at all. I do have my DigiQ closed half-way and I open my top vent at least half on a normal day. Most cooks the DigiQ stops right on target and stays there. I have found (as friends have also) the DigiQ may, for no apparent reason, just up 10 degrees, or more, for just a couple minutes and go right back to target temperature. I personally do not think closing the top vent all the way would accomplish much except cause the blower to run more, but seems everybody has their own idea. Regardless, ALL my cooks have turned out wonderful food. I generally close my top vent to about half to 3/4 after I get to target temperature. Works for me. Good luck guys, it's sure fun experimenting. Hard to mess anything up even if you overshoot several degrees.
 
Just a tip for some with a Weber Mountain Smoker. Mine is an 18 1/2. This past Saturday I put a HUGE rack of spare-ribs on the top rack, and two racks of baby-backs on the lower rack. I normally cook them 3 hours and then take them off and put some honey, brown sugar on the ribs and pour in a bit of liquid (apple-juice, Dr. Pepper or whatever) and double wrap the ribs in foil. I put them back on for at least an hour to really tenderize them and allow the honey and brown sugar to form a delicious taste. Since I needed to smoke one more rack of baby-backs for my neighbor, I took all the ribs off when they were finished, took the top lid off my smoker, removed the middle section above the fuel bowl so I could see where the fire had burned, and was able to put more hardwood on exactly where I wanted it to give a good smoke to the fourth rack of ribs for the neighbor. I did this as quickly as I could, got it all back together, and put the one rack of baby-backs on the top grill. Temperature went crazy for a little bit, but settled down pretty quickly. Ribs turned out great. I used a HEAVY RUBBER GLOVES to lift the mid-section off the grill to avoid getting burned by the hot pit. Also, I never put water in my water pan, it just forms a heat barrier and also takes too long to heat water. I have my water pan wrapped well in heavy duty foil and bought a 14 inch Mexican Pottery Plate at Home Depot Garden Center(also wrapped in foil), right on top of the water bowl. Wrapping them in foil makes for an easy clean up and re-wrap about every 4-5 cooks. You sure don't need water in that bowl, especially if you take the ribs or brisket off and wrap in foil and add a liquid inside the foil and cook it another hour or so to get the meat juicy and moist. Just another idea and technique of thousands more out there. :)
 
Just to let you know what I've done last night, and today. I loaded my 18 1/2 inch Weber Mountain Smoker up pretty heavy with Stubbs Charcoal and quite a bit of a mixture of Hickory, Oak and Pecan, mostly Hickory. We like a real smoke flavor. I opened my top vent about 1/4 of the way and set my DigiQ 2 on 210 degrees and lit the fire. It has been "Pegged" on 210 since last night about 9:30 p.m., Central Time. My internal meat temp on a rather large pork butt (9 pounds) is currently at 161. So I have a ways to go to get to my meat temp target of "about" 200 degrees, so after I get back from having lunch with friends I may crank up the temperature to about 235 and hope that my wife and I can have pulled pork when she gets home about 6:00 p.m. Just thought I'd share that the top vent is only open about 1/4 way as I hoped it would burn more slowly and I would not run out of fuel as long as I'm cooking this pork butt.

It's fun to experiment. I rubbed the butt down with mustard, then sprinkled brown sugar on it then finished it off with Bill's Texas BBQ Rub (Original Rub). It's gonna be good. :)
 
Just to update on my previous post about the 9 lb. pork butt. I let it smoke for about 18 hours and when I got home from lunch it had stayed pegged at 210 pit temp. I wanted it for dinner last night so I cranked it up to 250 as my internal meat temp was only up to about 160. To make a long story short, it finally hit 192 and I had enough waiting. I took it off after 19+ hours of smoking and it was fabulous. I learned to NEVER buy a pork butt that large again as they take forever to smoke. There's just two of us so I don't need that much, but had planned on giving some away to our kids and a neighbor. I left my top vent open about 1/4 way the entire time and the little DigiQ 2 kept it nailes on 210 until I bumped it up. Once I bumped it up, it kept it nailed on whatever I put it on. I have not opened the pit to see how much fuel I used but I'm telling you this little Weber Mountain Smoker 18 1/2 inch will go for 24+ hours if you load it with fuel. I used Stubbs Charcoal Briquettes and lot's of hickory and a bit of oak and pecan just for good measure. I put some brown sugar on the butte and then covered it with Texas BBQ Rub. You know what I'll be having today for lunch and dinner ? Hope this helps someone.
 
You must log in or register to reply here.

 

Back
Top