I would make it just a little bigger. In my opinion if it is smaller than throat opening it would hamper the heat and smoke flow through the CC. I think it would be easier to add just a little to each end of the BP if needed than cut it.
jm2cw
Well right now, the throat opening is very oversized (144 sq inch, recommended size is 78) I am going to have sliding adjustable baffle plates, as my design allows for it very easily and I have spare steel of the right size.
My thought though, with Centre feed, the baffle plate and the throat opening is kind of one and the same thing...? I have a shaddow plate over the opening and surely the restriction of airflow will happen at the baffle plate gaps, so why bother restricting it twice? M feeling is to let the air come out of the oversized throat then the slow down will happen under the baffle plate. This may even help distribute heat, as more heat is retained under the baffle.
This is the throat and shadow plate as it is now. I added up the four openings around the shaddow plate, adds up to 96sq inches, so that will act as a bit of a throat too...
The FB generates 2 things:
REAL hot radiated heat.
Boatloads of REAL hot air.
Radiant:
The bottom surfaces of the roof of the FB and the lid of the "top hat"(shadow plate) takes the first hit from the radiant heat which they then absorb and SLOWLY transfer that heat to it's top surface and re-radiates it on up to the bottom of the main BP and so on....
This gives the convective heat output of the FB a chance to spread the heat ALL over the cabinet and greatly reduces the hot spot that would be right over the FB throat without it. It also helps step down the FB temp to a level in the CC that we like to cook at.
In my opinion the throat in this design is the gap around the edge of the top hat lid - once all that hot air hits the comparatively HUGE volume of the CC it RAPIDLY expands and speeds up and can easily slip through even a small gap.
Convective:
Edgar called for a 72 sq. inch throat so that's exactly what I gave him. I designed him with adjustable BP gaps at both ends. I ended up adjusting those gaps to about 3/4 inch on each end which is a total combined gap of 30 sq. inches. Sounds constrictive doesn't it? What you need to remember is that you can pass the same amount of air through a smaller opening if it's Much Hotter and thinner and very highly motivated (faster) especially when you add the stoking qualities of the cabinet/draft/stack etc. I wouldn't worry much about the numbers you've listed so far - shouldn't be a big deal.
Then again I could be completely wrong.
And on the eighth day God created barbecue …. because he DOES love us and he wants us to be happy.
Current smokers: Egor (trailered RF) and Easybake (tabletop pellet drive)
That's the biggest gap they'll ever need to be. You can always add a steel plate to each to close it off if you want to experiment with a smaller gap(s) later.
Sorry DC but I think that is actually what's going on in one of these things…..
And on the eighth day God created barbecue …. because he DOES love us and he wants us to be happy.
Current smokers: Egor (trailered RF) and Easybake (tabletop pellet drive)
And on the eighth day God created barbecue …. because he DOES love us and he wants us to be happy.
Current smokers: Egor (trailered RF) and Easybake (tabletop pellet drive)