Is the "chimney effect" just a myth?

Heisenberger · 10-03-2012, 04:45 PM

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 · 10-03-2012, 05:07 PM

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 · 10-03-2012, 05:12 PM

Quote:

Originally Posted by 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.

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 · 10-03-2012, 05:22 PM

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 · 10-03-2012, 05:35 PM

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 · 10-03-2012, 05:41 PM

Quote:

Originally Posted by 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...

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

Heisenberger · 10-03-2012, 05:42 PM

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 · 10-03-2012, 09:20 PM

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 · 10-03-2012, 09:33 PM

AustinKnight · 10-03-2012, 10:05 PM

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 · 10-03-2012, 10:05 PM

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

Harbormaster · 10-04-2012, 06:50 AM

Quote:

Originally Posted by 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.

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 · 10-04-2012, 07:02 AM

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 · 10-04-2012, 07:21 AM

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

Smoking Westy · 10-04-2012, 08:27 AM

Quote:

Originally Posted by Harbormaster

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!

10-03-2012, 04:45 PM	#1
Heisenberger Got Wood. Join Date: 09-07-12 Location: Austin Downloads: 0 Uploads: 0	Is the "chimney effect" just a myth? 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...

10-03-2012, 05:07 PM	#2
CarolinaQue is Blowin Smoke! Join Date: 06-23-07 Location: North Berwick, ME Downloads: 0 Uploads: 0	I would plug thos 8 smaller holes off and put in a single 2 1/2" to 3" diameter X 12" long exhaust pipe. __________________ Tim “Travel is fatal to prejudice, bigotry, and narrow-mindedness, and many of our people need it sorely on these accounts.” - Mark Twain - Beautiful family - Home made trailer mounted reverse flow offset w/ vertical chamber, Weber OTG and an ECB

10-03-2012, 05:22 PM	#4
landarc somebody shut me the fark up. Join Date: 06-26-09 Location: San Leandro, CA Downloads: 0 Uploads: 0	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. __________________ "perhaps...but then again...maybe not..." careful there son, those ribs are boiling hot... \_\|_/ (='.'=) Here there be bunnies... (")_(")ooo Pacific Rim BBQ Bob's Brew and Que

10-03-2012, 09:20 PM	#8
Smoking Westy Full Fledged Farker Join Date: 06-10-12 Location: Bloomington, IL Downloads: 0 Uploads: 0	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... __________________ WSM 22.5", One-Touch 22.5", Redhead 18.5" Smoke Joe Silver, Q200, "Mr. T"

10-03-2012, 09:33 PM	#9
Boshizzle somebody shut me the fark up. Join Date: 01-26-10 Location: Virginia Downloads: 0 Uploads: 0	__________________ Jambo Pit - UDS - Lang 60 (Sold) 18.5" & 22.5" Weber Kettles - Smokey Joe and Mini-WSM - Bubba Keg - #2 La Caja China Chargriller Outlaw Impeccably Accurate BLACK & RED Thermapens KCBS CBJ Operation BBQ Relief Founding Member I am Obsessive Compulsive about BBQ. Google it.

10-03-2012, 05:35 PM	#5
Smokin' D is one Smokin' Farker Join Date: 12-11-07 Location: N. Andover, MA Downloads: 0 Uploads: 0	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.

10-03-2012, 05:42 PM	#7
Heisenberger Got Wood. Join Date: 09-07-12 Location: Austin Downloads: 0 Uploads: 0	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!

10-03-2012, 10:05 PM	#10
AustinKnight is One Chatty Farker Join Date: 08-23-10 Location: Austin Texas Downloads: 0 Uploads: 0	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 __________________ \|HOOK'EM UDS\|MINI UDS\|22.5 WEBER PERF\|B&B\|OAK & PECAN\|DIGIQ\|TW8060\|THERMAPEN ORANGE\|Char-Griller Akorn\|Thin Blue Smokery\|

10-03-2012, 10:05 PM	#11
Johnny_Crunch Babbling Farker Join Date: 04-03-10 Location: Cypress TX Downloads: 0 Uploads: 0	The 8 hole design with no nipples works fine. Don't over think this. KISS! __________________ J Crunch

10-04-2012, 07:02 AM	#13
Terry Hesticles Is lookin for wood to cook with. Join Date: 09-13-12 Location: Edmond, OK Downloads: 0 Uploads: 0	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.

10-04-2012, 07:21 AM	#14
captndan is One Chatty Farker Join Date: 06-29-11 Location: Greeneville TN Downloads: 0 Uploads: 0	A steel pipe cap spells burned hands to me. How about a cork? Just an idea.