UDS Diffuser Throwdown

bigabyte said:

I have heard of people setting up their tuning plates in their offsets based on similar tests, using biscuits or what-not. I had forgotten all about it until seeing this thread. It's the first I had seen someone do this in a UDS (or other vertical for that matter), at least that I can recall anyway.

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Yeah, the biscuit idea was not my own. I saw it somewhere else. I had intended to make that clear, but I guess I left it out. Thanks for confirming that others do this test. I'm glad that I can be the first (that the great bigabyte knows of) to do it with a UDS. :-D

SmokerKing said:

I've been testing a few designs the past several months and this one is working out so far. I works not only as a diffuser but equalizes the center and outside temps to within 10-15 degrees or so. Last smoke the center and the side thermos read within a few degrees of each other throughout the entire rib cook;

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That really is awesome. I've seen some of your posts before, and that is what made me want to try a bundt pan. But, I must say that I'm surprised that that is winning design so far. I'm not questioning you, just expressing my surprised. It doesn't seem like it would be much different than a small diameter bowel like I used. Could you be getting a hot spot in between your outside edge thermometer and the center? I would love to try something like that out some day. Good job.

bdodd444 said:

I like that grilling wok idea, but the pictures led me to another question. Where are you placing your difusers?

I have 3 UDSs, and for my butts and briskets UDS. I have a 3rd grate about 6 inches below my lower grate. I wrap that with foil and poke holes in it. I have played around with placing two disposable 1/2 pans with water on it directly below my brisket. It worked well for my brisket (two fifth place calls), but the butts on the top grate took forever. I'm wondering about putting "grill wok type" diffuser over my charcoal basket as in the pictures above. This is a great thread, unfortunately 1/2 the pictures aren't visible to me (just a white box with a red X). Thanks.

Brian

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This is something I've been thinking about. I put the rack for my diffuser ~10" below my upper cooking grate. So, a flat plate would be 10" below, while the rim of a bowl will be 6" below the cooking grate. I put it here for two reasons, one is that the top of the bowl in a Weber WSM is ~9" below the top cooking grate. But, the other reason was that this put the grate about 1" above the top of my fire box (12" sides) and I couldn't get it any lower. So, this puts it about 13" above the bottom of the fire box or about 16" above the bottom of the drum. That is a lot of dimensions and a picture is probably worth a 1000 words. Sorry...

My current thinking that it is best to get the diffuser as low as possible so that the air between the diffuser and grate has an opertunity to spread out and even out.

I do worry about my diffuser being too close to the fire box, but so far I haven't loaded it up more than probably 4" high, so I think there is some room.

I also wonder if a bowel or funnel shape is more efficient to move air out than a flat plate or pot. Don't know. Who would have ever guessed there was so much science to smokers.

Picked this up at Lowes today. Actually, it is an 16" on top of an 8". I'm thinking it has a little bit of a funnel effect. It will also create a big air space, heat sink. Is this all good? Who knows. I'm doing a pork but tomorrow, I guess we'll see how it works.

Question, foil just the top, or the top and bottom, or does it not matter?