S7 Ep4: Finding The Sweet Spot: Smoker Efficiency VS Your BBQ Results

[@tRdoc21]

Great episode, Frank! Always love learning more about pit design, running a pit, BBQ, flow management, etc. Thanks for sharing!

[@konoctiswigwam8130]

Frank, would like to get your opinion. Kerry Mooney, a retired fire officer, designed a pit that uses a collector on each side of the chamber to even out the heat, he calls the fire box side a diffuser, which he designed with the Goldee's elbow and a direct flow. There has been so much debate on heat across the grates, but his design seems to cook the biscuit test the most even I have seen in any video. I'm preparing to build my own smoker, and planning to use Kerry's design as it takes so long to build a smoker that I figure I might as well do what feel right to me. Do you have any opinion on Kerry's design? You can find it by searching for "new design backyard offset smoker...no hot spot" EDIT: I should add, most offset smokers have such a large grate area, that I could easily have enough space with a traditional Franklin style pit by just not cooking in the hot spot. Same with The Solution that you build.

[@SmokerBuilder]

@@konoctiswigwam8130 hey buddy, I have seen one of the videos you mentioned. The real thing to keep in mind is it doesn’t really matter how the air comes into the cooking chamber from an offset firebox, it always wants to go up simply because the hot air mass is less dense than the cooler air mass. The air mass coming out of the throat is supercharged with heat. One big difference between the Goldies pit design and our design is the size of the opening allowing that air mass to enter the Cook chamber. This is the literal square inches of opening and includes the length of travel in order to get into the cooking chamber. When an opening is small, the volume of air is restricted, but the velocity increases. The naked eye it looks like we’re moving a lot of air really fast however it’s a smaller amount of air going faster. The elbow has what’s called friction loss and you have to take this into account anytime you’re moving air or any other fluid through duct or anything like that. The walls of the tubing, etc. have friction that causes the air to spin and slow down on the edges of the air mass, this also causes restriction in the total volume of usable space for the air mass to travel. By the way, I’m not saying any of these methods aren’t good enough or don’t work. I’m just saying that these methods of transferring the air mass from a fire box into the Cook chamber have some other considerations that affect performance. In the solution offset, we have a massive opening this allows that supercharged superheated air mass to chill out a little bit as it rises to the top. Our baffle system simply guides the air where it wants to go and encourages the cooler air mass to spin upward. By the way, the spin I’m talking about is lengthwise in the pit I do not believe that air spins like a corkscrew down the length of a pit. That would only happen if we were a full column of pressurized air or fluid going down the length of the pipe for a long distance . I hope that helps, I talk about a lot of this stuff in smokerbuilderu.com in our BBQ pit engineering with Frank Online course

[@konoctiswigwam8130]

@@SmokerBuilder Yes, that does help, that's for the reply. Kerry seemed to restrict the throat to 28 sq.in. which is compared to the Goldee's elbow. Seems the grates in the middle of the throat may help with that, not exactly sure. But it did seem his biscuit test was very even, and the temps seem the lowest at the throat where the firebox enters the chamber. That seems the opposite of being hot coming in. In Kerry's case the hottest spot (just slightly) is in the center, not the ends...but it was only a few degrees.🤔

[@konoctiswigwam8130]

@@SmokerBuilder I was just thinking about what you were saying and it makes sense that the air condenses into the chamber through the opening. What if that area was insulated with firebrick or kao wool ? Would that reduce the hot spot? I was watching one of Johnny White's videos where he's cooking 8 med sized briskets on their smoker. He builds the fire directly under the elbow, and during the cook he needs to rotate the briskets anyway, due to the hot spot.. That's exactly what I was hoping to avoid. I have been using a Weber Smokey Mountain with an old Rock's BBQ Stoker for about 20+ years. I don't use any water pan, I replaced it with terracotta dish I got at Home Depot, 20+ years ago, I wrap it in foil, let the grease cool and it cleans up. It's a different way of cooking, I only use oak lump charcoal, mix with Kingsford or Cowboy on a long cook. This basically turns my WSM into an appliance. But in regard to the Stoker I use, with the advent of wireless probes like the Meater, you can still monitor the meat, so as long as one keeps it within 25-50 degrees, they can still see what the actual meat is doing without opening the pit. BTW, one downside to my setup, I do use what is known as the Minion Method, but once I open the pit, it's difficult to stabalize again, it will do it, but it takes a while...I guess my questions is if insulating the opening between the firebox and chamber would reduce the hot spot? (with the intent to keep it a more even smoke)