UDS Diffuser

Anchors Smokeshop

Anchors Smokeshop

is one Smokin' Farker
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I used my UDS this past weekend for the first time to smoke some ribs and the bottom of the 2 racks that were on the lower grate got burnt.
The temp in the drum never got over 230 and there is plenty of space between the charcoal basket and the lower grate.
I think I need to add a diffuser below grate but this seems like it will defeat the purpose of allowing the drippings from the meat drip onto the coals.
Does anyone use a diffuser in their UDS?
If so, please explain how you set it up. Pics will help too!
 
Ok, where and how were you measuring your temps? Was there a reason you had the ribs on the lower rack? I use a diffuser at times depending on what I am cooking. Below are some that I have played with. Having holes will allow some of the drippings to get through while still diffusing most of the heat around the sides. Many people just use a clay dish wrapped in foil for easy cleanup.

IMAG0088.jpg
 
Okay I got a question how far above the coals do you place the diffuser, or how far below the grate also how do mount it in the drum? I don't have one but would like to try using one to see what difference it would make.
 
I put an old wire grate on top of my charcoal basket,
then I set a oval aluminum throw-away turkey pan on top of that.
I flatten it out a little and that is my diffuser.

I also had 2 layers of ribs on my UDS. I switched the grates of food half way through my 1st 3 hours of my 3-2-1- smoke. The bottom grate does get hotter than the top. My spare ribs finished in about 4 hours. Maybe over cooked. They were fall off the bone.
 
All of my smokers use a metal smoker plate(diffuser). The idea has many advantages, but mainly for me is separating ashes from following airflow from firebox to product. Another is, for my units, is slowing the airflow down to a manageable level. That means on this design, that's the only air rising is through the holes, making temp control easy. The juices from the product still evaporizes on the smoker plate, giving flavor, less ash. You can see the diffusers we sell at www.BarrelSmokers.net. The ones listed are for 55gal. models and we will make ones for 85gal. and 110gal models as per request. Thanks. Steve.
 
Some times I place another "coal" grate on top of my firebox and add water to an aluminum foil pan.. Similar to a WSM. All depends on what I am cooking. Ribs yes, Pork NO
 
I am planning to add an option for a diffuser to my UDS as I build it. I was wondering if I could just add a third cooking grate just above the fire box for the purpose of holding whatever diffuser device I decide to use? Will a cooking grate hold up to the temps that close to the charcoal basket?
 
JMSetzler said:
I am planning to add an option for a diffuser to my UDS as I build it. I was wondering if I could just add a third cooking grate just above the fire box for the purpose of holding whatever diffuser device I decide to use? Will a cooking grate hold up to the temps that close to the charcoal basket?
Click to expand...
Or you can build a taller charcoal basket and place the diffuser on top of that.
 
JMSetzler said:
I am planning to add an option for a diffuser to my UDS as I build it. I was wondering if I could just add a third cooking grate just above the fire box for the purpose of holding whatever diffuser device I decide to use? Will a cooking grate hold up to the temps that close to the charcoal basket?
Click to expand...

That's what I did on mine. It's about 8 or 10 inches above the top of the charcoal basket, not right on top of it. I've used pizza pans, (with & without holes ), foiled clay saucers, and even a water pan GASP :shock: ! Seems to work for me. Your mileage may vary.
 
On my charcoal basket I have a piece of rebar in the center that extends out the top. On the end I welded an eye hook upside down so the threads are on the very top. This serves two functions. First, I can reach in with another hook and pull up the whole basket through the hole in the eye hook. Second, I can drill a hole in any diffuser plate and thread it onto the threads. I wish I had a pic of it but I cannot find one. Anyway, this works well for me but really serves the same function as just having another rack level.
 
JMSetzler said:
I am planning to add an option for a diffuser to my UDS as I build it. I was wondering if I could just add a third cooking grate just above the fire box for the purpose of holding whatever diffuser device I decide to use? Will a cooking grate hold up to the temps that close to the charcoal basket?
Click to expand...
What you described is what I did. I've got a Weber cooking grate 9 inchs below my real cooking grate.

I started with a 10" aluminum pie pan and that reduced the temp difference some. This week I put a 16" aluminum pizza pan ($4 from Walmart) there. I drilled some 1/4 inch holes in it to drop the drippings. The heat difference this time was a max of 20 degrees with normal difference 15 degrees. My side measurement is only about 1.5" long so 15 degrees is pretty good from center to 1.5" from the side.

The diffuser changes your intake adjustment a bit. When it spreads the heat out, it takes more oxygen to get the center heated to 250 as well as getting the side to 235. Before the center was 250 and the side was about 190. My intake settings went from only the ball valve wide open without the baffle to one cap open and the valve 2/3 open with the baffle.
 
Carbon said:
Or you can build a taller charcoal basket and place the diffuser on top of that.
Click to expand...

That's what I have, I use a pizza pan drilled out, I also can adjust the height of my charcoal grate, I can raise it if I want to use it for grilling.
 
Last edited:
pman777 said:
The diffuser changes your intake adjustment a bit. When it spreads the heat out, it takes more oxygen to get the center heated to 250 as well as getting the side to 235. Before the center was 250 and the side was about 190. My intake settings went from only the ball valve wide open without the baffle to one cap open and the valve 2/3 open with the baffle.
Click to expand...
Exactly my experience as well. And also more oxygen equates to more fuel spent.

Off topic but this is another instance where I like having just one single large intake vent/control instead of having 3 or 4 smaller vents to deal with indivudually.
 
Thanks for all of the suggestions.
As a temporary solution, I added another grill grate below the lower grill grate so there are now three levels.
The lowest grate will hold an aluminum tin filled with water while the upper two grates will be for cooking.
 
I used a 16" terra cotta pot base as a diffuser in mine (as do numerous others, not my invention). It works really well to diffuse the heat, retaining the heat, and doesn't need refilled like a water pan. Check out your local Lowes gardening section.
 
We don't use a diffuser and have never had a problem. We like the campfire flavor imparted in the meat so don't use one. Depending on how you built your drum, you might need to rotate the racks one time but other than that, I see no need. But, do whatever you want and it will be fine.
 
Question for those that don't use differsers....
Do you use 18" diameter or larger charcoal baskets?
 
Don't think that makes any difference but interested in why you asked. Why 18" diameter?
 
Meat Burner said:
Don't think that makes any difference but interested in why you asked. Why 18" diameter?
Click to expand...
Many, or should I say most baskets I see are fabricated around 18" charcoal grates from 22.5" kettles. I made mine from a 13" charcoal grate (from my modified ECB) which I am using for the time being in my new UDS.
I was basically wondering if a wider charcoal basket created less of a hot spot at the center of the cooking grate compared to using smaller charcoal baskets.
 
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