Can a UDS air intake be too tall?

[N8man]

Originally Posted by chinesebob

Off topic but N8man - how did you build yours on to the wheels like that?

Try this: http://www.bbq-brethren.com/forum/sh...&postcount=124

[JamesB]

Thanks every1 for all the ideas. I will let ya know how the next cook goes... I'm going to try a shorter pipe and then no pipe for comparison...

James.

[wlh3]

Here is my Drum> I have a 2" inlet pipe and a 3" exhaust thats all. The only thing I did different after the first few cooks was use my lid band. This helped my Temp control alot. I can now pretty much dial in the temp I want and it stays there. I think once you go to a shorter air inlet pipe and try the lid band temp control could improve for you

[JW]

James B it is best that the air intake does not extend above the height of the barrel, also your exhaust needs to be at least 1/2 inch larger in diameter than the air intake, this will help with creating a draft. WLH3 used a design that I have been using for a couple of years now with rather good success. I just made one for my dad and during the seasoning process he was amazed at how much air he could feel being pulled into the air inlet tube. Look for some of my post in the UDS thread around page 18 - 19 and check out what WLH3 has done with his barrel, I find that keeping the inlet about 2 inches below the top rim of the barrel with a single large exhaust gives the best results.

Minimum recommended tubing sizes: 2" inlet with a 2 1/2" exhaust.

Hope you get it going soon.

[CritterCook]

I have had great luck keeping temp with mine. I'm a newbie with these but maybe with larger exhaust it might draw harder.

[FatDaddy]

Was lookin for this thread... when i built mine i thought taller intakes would be better. Im running 1/2" intakes 4 of them. 2 with the vertical pipe/ballvalve/90* on the end. Well was planning on cookin 2 spatchcocked chickens this after noon started my fire about 330, couldnt get it past 250* which i guess was good for brisket etc. but i wanted to take it higher. I started out with about half a chimney of lit coals to a minion method. I just dump lit coals all over the top( no can method) I got to reading and decided to take the long pipes out and just run the ball valves on the sides. soon as i did that and let it sit for a few min temps started climbing. well i decided to fire up the kettle for the chickens, but i bought a chuckie as well so im throwing it on the drum. But i can attest that having the intakes higher than the exhaust will definitely make controlling temp harder. its running at 245-255 now still tryin to get it dialed in. have 1 nipple open and 1 valve half way.

[Dr_KY]

I can see where having the intake higher than the exhaust can cause a problem as in it not knowing where to pull clean air from and causing it to 'vapor lock' if you will.

[Meat Burner]

Originally Posted by JamesB

That's an interesting concept...

I am thinking browser has a good point. When I first saw your UDS, I wandered if the tall intake would act in reverse of a ciphon and try to pull the air in from the lid. I think you already have plenty of intake and exhaust..or at least close. Mine all work fine with weber lids which only have 4 - 1/2 exhausts. Just my $.02.

[Dr_KY]

I should have read Browsers post.

[FatDaddy]

yea.. still havin issues of temps fluctuating but i think it is due to the learning curve. I have 1 intake open now and valve 3/4 open, it had climbed from 235 to 250 or so... will play with it through out the evening and see what i can get it to stabilize at. im thinking i need 8 little flat magnets to put over the exhaust holes when i close it down at night. other wise im loosing a lot of charcoal lettin it burn down every time.

[Bbq Bubba]

My UDS knowledge has grown from my first post on this thread...
I now have 2 drum's, 1 with 3/4" intakes and cap's w/ 1 ball valve down low and now 1 with a riser, have used them both in similiar weather condition's, not playing know it all but have done my homework!!!

Model with riser is much harder to lock in temp, don't know if it's the volume of air IN the pipe that has to stabilize or the height issue with it reverse flowing but it IS a different beast, actually saw smoke EXITING the intake on several condition's!!
It finally did settle down at 228* after some fidgiting and stayed for several hour's but seemed to burn thru the coal twice as fast! 8# only lasted 10 hr's...

First drum is 1 cap off, valve open about 1/3 and run all day at 235, no question's asked, plus i have done a high temp chicken cook at 325 with great success.....

Just my opinion having used both system's....
Btw, i have a 2" exhaust on both lid's....work's GREAT!!!

[Meat Burner]

Bubba, seems like a lot of brethren have a 2" exhaust that works very well. Whatever intake is used seems to work with that setup since the temp is regulated by the intakes. KEEP IT SIMPLE!!! Just thinking outloud and getting ready to mix up an adult bev.

[Norcoredneck]

Simple equation, simple answer. Path of least resistance. The fire will draw air from exhaust if it is easier, especially if larger diameter.

[motley que]

Originally Posted by Norcoredneck

Simple equation, simple answer. Path of least resistance. The fire will draw air from exhaust if it is easier, especially if larger diameter.

i ditched my 2" exhause as i found it hard to control temps with a 1" intake pipe. as soon as i did that, and drilled the holes into the lid, the drum holds temp better.

I truly think that using 3-4 intakes at the bottom works best. if you dont want to bend over to adjust the valve, just use your foot. my valve isnt the rotating type so i know how much its open or closed

[Meat Burner]

There is always ways to make improvements. Also, don't fix it if it ain't broke. This forum always offers new idea...which is great!...but goes back to the basic UDS design, which is simple. Always look forward to new ways to tweek the UDS. Thanks to all the ideas.