Is the "chimney effect" just a myth?

[Heisenberger]

Hello Brethren. I have a question about my UDS exhausts. Will threading the 8 holes in my lid with nipples create any chimney like effect (if that exists), or is it exactly the same as just having the holes bare. Does having a chimney actually "draw" the air/smoke out? Maybe this only happens if the chimney is a certain length.

I'm debating whether I should thread the holes with a pipe plug to close it off, or just install the nipples and use caps for cutoff...

 

[CarolinaQue]

I would plug thos 8 smaller holes off and put in a single 2 1/2" to 3" diameter X 12" long exhaust pipe.

 

[Heisenberger]

I would plug thos 8 smaller holes off and put in a single 2 1/2" to 3" diameter X 12" long exhaust pipe.

My original idea was to do this, however, I have a flat bung-less lid and my step drill only goes to 1-3/8'', which would make a hole fit for an even smaller pipe (maybe 1-1/4'').

 

[landarc]

I have seen UDS's that work fine with several small holes in a flat lid. Some that even just had pieces of steel or magnets to cover the holes. I agree that a larger chimney would work better. But, you have what you have. Go for it and see.

 

[Smokin' D]

I sometimes will slip a can over the exhaust on my WSM. Certainly seems to produce a better draw than without. Could be just my imagination though.

 

[1MoreFord]

Hello Brethren. I have a question about my UDS exhausts. Will threading the 8 holes in my lid with nipples create any chimney like effect (if that exists), or is it exactly the same as just having the holes bare. Does having a chimney actually "draw" the air/smoke out? Maybe this only happens if the chimney is a certain length.

I'm debating whether I should thread the holes with a pipe plug to close it off, or just install the nipples and use caps for cutoff...

It's actually called stack effect and it is real.

You can read about it on Wikipedia. I'd drop a link but for some reason the forum won't let me. I keep getting an error:crazy:

 

[Heisenberger]

Ideally I would like to make a chimney, theres just no way for me to make a 2 inch hole without some outside help. I even thought of making 2 exhausts each 1-1/2''. I don't mind doing extra work or buying a few extra parts. I see this build as a weekend project and I would love to maximize its potential. Can't wait to try it out!

 

[Smoking Westy]

For my recent build I grabbed a 2 1/2" hole saw from Napa. It was fairly inexpensive and made quick work of the job. Added bonus is I now have the tool for future builds!

Not a typical UDS build by any means but you can see what I did...

 

[Boshizzle]

 

[AustinKnight]

I have what I think your talking about, and they work great for me most the time I only open 4 but to crank up the heat I'll open them all. I put them on cause of wind it helps with temperature control for me.Also keeps rain out and chokes out the fire fast using lump.

Sent from my SGH-T999 using Tapatalk 2

 

[Johnny_Crunch]

The 8 hole design with no nipples works fine. Don't over think this. KISS!

 

[Harbormaster]

I sometimes will slip a can over the exhaust on my WSM. Certainly seems to produce a better draw than without. Could be just my imagination though.

A Bush's bean can with both ends removed fits snugly over the top vent tabs and has a noticeable affect on WSM performance in less than ideal weather conditions.

 

[Terry Hesticles]

I've only cooked twice on my week-old UDS, but I used the KISS method with 8 1/2" holes in a 15" diameter across the top of my flat lid. So far it's worked great and seems to offer plenty of exhaust, neither of my meals were ashy/sooty. In fact, despite calibrating my thermo, I've worried through both cooks that it was stuck because it held at the exact temp I wanted it to for the couple of hours I needed.

I also smoke on my patio with a large overhang so it's safe from precipitation. In furthering the KISS method, when it's time to choke the flame, I shut off my intake(s) and tear off small bits of aluminum foil to plug the holes. I do so in a manner similar to bits of toilet paper on your bleeding shaving nicks. Leaving the bits flat, I use my fingertip to settle them down somewhat into the holes and then I use my palm to flatten the foil around the holes. Simple and secure and within an hour or so my thermo reads ambient temps.

 

[captndan]

A steel pipe cap spells burned hands to me. How about a cork? Just an idea.

 

[Smoking Westy]

A Bush's bean can with both ends removed fits snugly over the top vent tabs and has a noticeable affect on WSM performance in less than ideal weather conditions.

Good to know!

 

[willbird]

I've only cooked twice on my week-old UDS, but I used the KISS method with 8 1/2" holes in a 15" diameter across the top of my flat lid. So far it's worked great and seems to offer plenty of exhaust, neither of my meals were ashy/sooty. In fact, despite calibrating my thermo, I've worried through both cooks that it was stuck because it held at the exact temp I wanted it to for the couple of hours I needed.

I also smoke on my patio with a large overhang so it's safe from precipitation. In furthering the KISS method, when it's time to choke the flame, I shut off my intake(s) and tear off small bits of aluminum foil to plug the holes. I do so in a manner similar to bits of toilet paper on your bleeding shaving nicks. Leaving the bits flat, I use my fingertip to settle them down somewhat into the holes and then I use my palm to flatten the foil around the holes. Simple and secure and within an hour or so my thermo reads ambient temps.

My UDS snuffs out just fine without plugging my 1/2" holes

Bill

 

[TurboDog]

I use a weber lid on my UDS , and I had noticed that even the slightest breeze would mess up the draft , I set a scrap piece of 4" pipe over the exhaust and it seems to work way better. As posted above I could see a can with both ends removed work as well.

 

[tikiboy02]

I agree with Willbird. My flat lid has 8 holes and I can cut off the bottom vents and my charcoal will go out (save for another time). This is probably caused by the chiminey effect and heat.

 

[SkinnyVinny]

Well this is interesting. I have the flat lid, with a 2 inch bung on it and no chimney. Is this bad? I always assumed it was enough for smoke to escape.

For those that added a chimney, what did you use? I do have threads in the hole, just don't know what to look for. Similar piping material to the nipples?

 

[Mo-Dave]

The chimney effect is real that is why in ye olden day homes had tall chimneys so in the winter it made lighting and maintaining a hot fire much easier and in the summer it drew cool air through the home.

If I had a flate lide I would want at least a nipple taller than the edge of the barrel so water would not collect on the top and fall into the drum but I have a weber dome so its not a problem.
Dave