Temperature Regulation via Dome Vent


 
D

dave_scarpetti

TVWBB Member
Hey all,
Please don't attack me for this. I need to challenge the conventional wisdom.

What is the documented support for keeping the dome vent in a kettle or WSM full open? On a dry run, I can crack the bottom vent and completely control the dome temperature (on my kettle) like it was an oven - to 200 - 400+ degrees by using the dome vent.

I use lump with some mesquite or other woods for smoke. When I place the smoke pieces in, I don't smell anything bad (like I would imagine creosote to smell), just smoky goodness.

Any comments appreciated.
 
I can offer you years of anecdotal support (myself and others) but cannot document it per se.

I wouldn't expect you to smell 'anything bad' when putting smoldering smokewood into the cooker. The top vents are key to facilitating the draft as I'm sure you know. Closed, with restricted lower vents, means airflow is restricted and heat is harder to generate. With the lowers closed the fuel in the cooker cooker will (or should) extinguish.

Restricting the upper vents--especially during smoke generation--can cause the smoke particulates to linger. If the smoke is 'clean' this isn't necessarily a problem (though one can build a smoke layer rather quickly and it's easier to go over the top with smoke) but if the smoke is 'dirty' excessive build-up of 'off-flavored' particulates can render the meat virtually inedible.

That said, I use a therm with a silicone plug to monitor cooker temps more often than not. This restricts one of the three holes entirely. I have not noticed a problem doing this. Also, there have been times when I've needed to curtail a temp rise (my last cook, e.g.) and have closed the top vent by half. This hasn't posed a problem either.

Type and quantity of smoke being generated at the time the upper vent is adjusted seems to me to be the key variable. Sufficient airflow, imo, needs to be present if smoke quantity is fairly high in order to minimize the chance of an oversmoked finish.
 
So, it seems partial restriction may be alright? Thanks for the input.

I didn't do a completely dry run. Last night I cooked a chicken while eating dinner and tonight I'll sample it. If I got some nasty output from the smoke, I guess I'll taste it.

My problem is my kettle, even with the minion method, takes off in temperature and the only way I can moderate it is by how much fuel I charge.
 
Have you tried fire bricks is you kettle? It will help moderate temps considerably.

On my kettle (a Platinum) I use both lower and upper vents. But I don't use lots of smokewood when kettle-cooking, and keep a draft, restricting much more with the lower than the upper.
 
Yes, I used firebricks to keep the fuel banked against the side and the bottom (I think it's the one touch with the 3 slots regulated simulataneously) vents open just a crack. Still heats up too high for me.
 
Dave
The longer the cook the more of a problem closing down the top vent will manifest it's self.

I really don't worry about pit temps as long as they are in the range I'm looking for 200 to 265 is the norm. You may want to start with less lit charcoal and close the bottom vents down earlier in the heat up with the WSM.

Cooking with a kettle it's more about fire size than anything else for me.

I have always left the top vents open and have stayed away from using them for temp control.

On my ceramic cookers I do use the top and bottom vents for temp control but I also use less wood for smoke.

Jim
 
I'll control my kettle temps using the top vent, especially when using low temperatures. I won't however, do this with my WSM (unless temps get extremely out of control).

My thinking is this: As Kevin pointed out above, the top vent is used to control the draft. In the smaller space of a kettle, that draft will circulate more and thus the older smoke will have more opportunity to exit through the vent.

In the WSM, the draft won't circulate as fast and could therefore get stale, especially with the extended cooking times...

That said, I'm no engineer, so that could all be BS...
 
Previous post got eaten, here's the jist:

Kettle: yes

WSM: no

Kettle: more circulation and older smoke can leave quicker

WSM: Slow circulation, smoke gets stale, especially on long cooks.
 
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> Cooking with a kettle it's more about fire size than anything else for me. </div></BLOCKQUOTE>Ditto. I mini-Minion for lower heat cooks, start with a small pile of all lit for higher heat cooks or, of course a large pile of all lit for very high heat grilling sessions.

I have found that many people frustrated with lower heat cooks use too many lit; many frustrated with very high heat cooks use too few.
 
Kevin,
Got a link for the mini-minion?

By the way, this discussion is great. I used to post to the newsgroup alt.food.barbecue. It was a brutal forum. Pretty much seemed like a bunch of 15 year old cliquey girls.

Thanks again for all the ideas.
 
Sure do. David Lohrentz has a good set-up description here, using a kettle, firebricks and a mini.

This is a great board. People here are willing to share opinions, insights, tips--and the civility is second to none.
 
I was having the same problem with keeping the temp down in my kettle. I was using fire bricks and the mini-minion method.

You might give this a try as I’ve had some success this weekend.

I used the firebricks but not the minion method (no offence Jim). With the top vents fully open and the bottom vents fully closed, I added 1/3 of a chimney of lit lump charcoal. With that setup, the kettle maintained 300* at the dome for ~ 90 minutes. Not sure what the temp at the grate was, but the spares turned out great! The temp slowly dropped to 250* (at the dome) over the next 30 minutes. After that, I added another 1/3 of chimney of lit and got the same results (~ 2 to 2 1/2 hours of cook time).

Good luck Dave.
 
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Matt Denton:
I was having the same problem with keeping the temp down in my kettle. I was using fire bricks and the mini-minion method.

You might give this a try as I’ve had some success this weekend.

I used the firebricks but not the minion method (no offence Jim). With the top vents fully open and the bottom vents fully closed, I added 1/3 of a chimney of lit lump charcoal. With that setup, the kettle maintained 300* at the dome for ~ 90 minutes. Not sure what the temp at the grate was, but the spares turned out great! The temp slowly dropped to 250* (at the dome) over the next 30 minutes. After that, I added another 1/3 of chimney of lit and got the same results (~ 2 to 2 1/2 hours of cook time).

Good luck Dave. </div></BLOCKQUOTE>

Matt - try using less than 10 briquettes (similar amount of lump) on a big mess o' coals.

I don't use fire bricks and am able to maintain a steady 250 for 8+ hours.

The bottom vent is barely cracked.
 
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Matt Denton:
On a kettle? </div></BLOCKQUOTE>

Yep. That's what's great about the modified (or mini) minion method.
 
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Matt - try using less than 10 briquettes (similar amount of lump) on a big mess o' coals.

I don't use fire bricks and am able to maintain a steady 250 for 8+ hours.

The bottom vent is barely cracked. </div></BLOCKQUOTE>

Hmmm, thanks to both of you, seems the critical parameter here could be near complete closure of the bottom and use just the top? Piling on a small number of briquettes/lump on top of a pile seems like it would get the whole pile going and then the ramp up. At least that's what happens to me. Very interesting. I think I'll be doing a dry run tonight. (my neighbors are kind of curious about me firing up my kettle with no food inside - life of a hack scientist)
 
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by dave_scarpetti:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Matt - try using less than 10 briquettes (similar amount of lump) on a big mess o' coals.

I don't use fire bricks and am able to maintain a steady 250 for 8+ hours.

The bottom vent is barely cracked. </div></BLOCKQUOTE>

Hmmm, thanks to both of you, seems the critical parameter here could be near complete closure of the bottom and use just the top? Piling on a small number of briquettes/lump on top of a pile seems like it would get the whole pile going and then the ramp up. At least that's what happens to me. Very interesting. I think I'll be doing a dry run tonight. (my neighbors are kind of curious about me firing up my kettle with no food inside - life of a hack scientist) </div></BLOCKQUOTE>

Just to clarify -

Jay - I've tried the mini-minion method and i did not get similar results.

Dave - I don't mess with the top vents....wide open all the time.
 
Dave- The best part of BBQ is you get to eat your tests. Go pick up a smaller pork butt. The meat also acts as a heat sink and will help stabilize your temps while you test. You can finish off in foil in the oven if it gets late.

The beauty of the minion method is that by placeing the lit coals on top of the unlit is that is significantly slows the spread of the fire. If you put lit under unlit, the fire will spread much faster.

As for your cook, open the bottom halfway (leave the top open) until the temp is 20 degrees below your target temp, then start shutting the bottom. It should stabilize.
 
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