First UDS Test FAIL

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gatorman777

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First time I'm posting even though I've been viewing for quite some time.

I built a Chicago Bears UDS out of a 55 gallon drum. I've attached a pic.

This past Saturday, I did my first burn with no meat. I used Stubbs briquettes and used the minnion method to lite it. This is where the issues started. I was able to maintain 225 with one valve wide open. After 4-5 hours, the temperature started plummeting. I could not keep it above 150.

I noticed a few things that may help give me a definite answer. I've been searching this site with no definitive answer.

1) I only used the charcoal I lit with the chimney. It might have burned an additional 5% charcoal but I'm unsure.

2) Smoke was coming out of the intake stack along with the exhaust holes on the lid.

3) When I removed the lid, the temp plummeted instead of going up like I've been reading.

Outdoor temps were 50-55 degrees and we had mild winds. Intake valve opened was on opposite side of wind.

Any help would be greatly appreciated.
 

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Smoke should never come out of the intake.

Did you have all of the exhaust holes open?

May have had some bad charcoal.


Nice looking UDS.
 
sounds like maybe ash build up might have been blocking air flow. maybe a goos shake of the basket might help. Another possibility is tha intake, I see they are raised and possibly the wind pulled the air out the intake because it was on the back side, hence the smoke coming out of it. I turn my intake to the wind as long as it is not to bad. If real bad I make up a wind block.
 
Temps will drop while lid is off, but the fire will also build while the lid is off and you'll get a spike in temps after closing up. Try again and leave the lid off for a few minutes to allow the fire to settle in, then put lid on. If temps drop again repeat the process and if fire wanes you have your answer-not enough intake and or exhaust. Based on your pic it looks like you have those covered though.
What's your fire basket consist of? Let's see a pic of that. That's the only other variable as far as the cooker is concerned. If the aforementioned are all covered then if look to the coal. Was it damp in any way? Did you let them ash over before dumping and putting lid on? These are factors too.
 
Just looking at the picture, I'm going to guess it is an exhaust issue. Those holes look fairly small in the picture. If you are doing 8 holes, they need to be at least 3/4" big to get to the generally accepted minimum area of 3.14" (the same as one 2" hole). 8 3/4" holes will actually get you a little more, but too much exhaust is rarely a problem.

Try it again with your lid set off of the top of the drum ever so slightly. I'd be willing to bet your temps get right up where you want them.

Edit: Also, what size are your intakes and how many do you have? I can see three of them and I'm guessing they are 3/4"? An intake on a riser with a ball valve flows slightly less than a simple pipe nipple. Be sure you are giving it enough intake.
 
You need a bigger blow hole to let the gases out and a new Red White & Blue paint scheme
th
 
I built a Chicago Bears UDS
Click to expand...
It figures your UDS would sit on the sidelines of low temps and sulk.....

btw - your smoker is Class 'A' all the way!
 
First, those exhaust holes look like half inch holes - increase your exhaust to eight 3/4'' holes. Hell, you can even make two of them one in holes.

Second, adding a riser to the intake which results in the 90 degree bend of the pipe will massively cut down on your intake in my experience. Either make the intakes bigger, or remove one of the risers and just have it be a 3/4 inch pipe nipple with no riser. You probably need all three intakes open with your current setup.
 
I was waiting for the jokes!! My smoker acted like our coach, calm and extinguished. Maybe I should've built a Dolphin UDS.

I've attached a pic of my basket. This is what was left from a bag of Stubbs briquettes....after I shook out all the ashes from the middle.

I have 8 3/4" holes on top for exhaust.

I did shake the exhaust once and the temp went up a little. An hour later it extinguished.
 

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I hate to say it, but it looks to me that you never had a good hot fire going from the get-go.
You likely did not properly load and fire your basket.
Or had closed intakes.
 
Heisenberger said:
First, those exhaust holes look like half inch holes - increase your exhaust to eight 3/4'' holes. Hell, you can even make two of them one in holes.

Second, adding a riser to the intake which results in the 90 degree bend of the pipe will massively cut down on your intake in my experience. Either make the intakes bigger, or remove one of the risers and just have it be a 3/4 inch pipe nipple with no riser. You probably need all three intakes open with your current setup.
Click to expand...

My thoughts exactly
 
Take a step drill and enlarge your exhaust holes large enough to use a black pipe screw in plug. Increase the bottom gap of your fire box by a couple inches.
Fill the fire box at least half way and put 10 lit coals in the middle top along with several wood chunks here and there and I think your good to go.
Full exhaust open adjust air intake to set temps. Mine picks a temp of around 300.
Don't fight it just adjust timing to what your cooker gives you.
Go Bears!!
Ed
 
You also need to keep the fire basket a few inches off the bottom to get good circulation
 
That's an issue of ash build up, then. You should have 3-4" been the bottom of your basket and the bottom of your drum and/or ash catcher. I'm guessing ash build up is keeping fresh air from getting under your fire.
 
I stand corrected. The holes are 1/2" holes. I just went out there and measured. I will increase the exhaust holes to 3/4". Would that make a huge difference?

The way this thing was burning, it felt like I was smothering it and it just burnt the charcoal that I lit with the chimney.

With my setup, what is everyone's guess on how many valves should be open.
 
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