ATC Vent Mod (below the grate)


 
Brad Baker

Brad Baker

TVWBB Fan
I've been using a Flame Boss ATC for a couple of months. Like other ATCs, the standard blower mount uses an an adapter through a damper opening (daisy wheel). Because the daisy wheel opening is above the grate, I have always used some bent aluminum foil contraption to direct the incoming air down below the grate. I've noticed when using the FB, and another ATC that also injects combustion air through the damper opening, that because of the location of the air injection, the fire closest to that spot gets used up first. Also, BBQ on that side of the cooker has a higher temperature than than on the opposite side. It seems to me that to even out the temperature and consumption of the fire the air should enter the fire from below the grate at the center of the ring rather than above or it to the side.

Using a step drill, I bored a 1 inch hole in the bottom of my 18.5 WSM. With some minor work with a round file, a 3/4 inch EMT large radius 90 degree compression elbow will fit. I cut one inch from one end of a 3/4 inch EMT 45 degree elbow and inserted that into the compression fitting. The diffuser, shown in the fourth photo, is a can that contained cooked chicken. The Flame Boss blower has a spring loaded retaining BB on the nozzle. I drilled a 1/4 inch hole to receive that in the other end of the elbow.

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Interesting idea! Post again after a few cooks and let us know how it works.
I was wondering, could you set a “pad” of mesh inside the diffuser can and have the blower lift off the jett when it goes into a flow cycle? Or use an inverted funnel? I wonder if the airflow would be sifficient to blow the hole clear and lift the runner just enough? I think you might be on to something...
 
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Nathan FA said:
Looks pretty good. Should be a pretty even distribution of the air.
Here is a thread that had a bunch of different options for attaching a blower to your smoker. I found this option in the thread and did something similar to you but used copper tubing to make a "burner" ...
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Good thread reference. One thing I was wondering about this approach (air from below). I'm using two crossed grates to prevent small pieces of lump from dropping below the grate. It also seems to hold more ash, which would seem to be a good thing unless it blocks the flow of air from underneath. I suppose in that case the air will go up around the sides. I'll have to keep track of it over the next few cooks. So far it has worked out well. Have you ever seen it to be a problem?
 
I use the cross grate as well, I have never noticed any issues with airflow being blocked and my coals seem to burn a a fairly even rate across the whole tray.
 
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