Throat Opening Placement

[Fattdaddy]

I am starting into a 250 gallon build and was getting ready to make the cut into the tank for the firebox. I have found the center of tank and am wondering if the top of my firebox should come into the CC at grate height or under?
I plan on using tuning plates so my initial thought was to have the top of the FB about 3” lower than grate level which I an on my tuning plates being 3” under the grate.

Any thoughts or advice would be appreciated!

Thanks,
Fattdaddy.

[Back9Q]

I guess first thing is what style FB are you using? Round,square,insulated, etc?

That will help us give you advice on placement


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[Fattdaddy]

Right now Im thinking about doing a square FB that will be insulated.

[Pete Mazz]

Keeping it low will help with not getting a hot spot at the throat exit. Tuning plates are the way to go IMO.

[Back9Q]

Two options I see with insulated. Mount it dead center of tank for following reasons

1. Appearance
2. Due to insulation the top of the box and top of opening will be roughly 4” which is what you are after

Other option is mount high and have opening at grate level taking heat up to top quickly and down to stack. Non tuning plates for this method. Think Jambo/outlaw smokers


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[Dirtytires]

In all honesty, I would decide on and build your firebox before you cut into the tank. The shape you cut is determined by the finished shape of the firebox and, right now, you don't know that.

However, mounting the firebox low on the cook chamber will allow for better use of the tuning plates and more usable rack space.

[Fattdaddy]

Thanks for the input. The only other thing if someone could help me out with is the throat size (opening from FB to CC). I could do either a rectangle or trapizoid.
Here are my measurements 250 gal tank, 6” round stack, square FB 27”x30”x24”.

Thanks in Advance!

[SheffSmoker]

If you see the link at the top of the page, you can punch your numbers in to get the throat size from that.

https://smokerbuilder.com/forums/app.php/pit-calculator

[Dirtytires]

Shape of the throat makes no difference. I like to keep it as low as possible and use the tank as my template to see what shape I can make it.

The throat calculator will give you the area of the throat and then you can plug that into the shapes calculator to see what size works best.

[breavis]

My thinking is if you keep the throat below the grate it's not as bad to have flames getting close to the meat.

[ThinBlue]

Would having the throat at the bottom of the CC theoretically promote better convection or is it negligible? I'm trying to understand figure out if companies, or backyard builders, have a rhyme or reason for choosing to place it grate level or at the bottom of the CC.

[Brewmaster]

Good question! One that I can't answer but I will say that if you look at all the bigger or more sought after (debatable? haha) builders' patio models, they all seem to have fairly common placement of a couple inches below center/grate level, or pretty much at grate level. One slightly odd one out are the Workhorse models where the box is indeed installed at grate level, but the throat opening is on the bottom half of the chamber. So on the 94 gallon size (1975) that places the opening about 6" below grate level, with 6" height throat opening below to the bottom of the food chamber, and I can attest the design works amazingly well, at least when combined with the massively over-sized firebox.

[SheffSmoker]

On my 3rd build now, and I've put them all as low as possible, and the FB as low as possible to match. I want the radiant heat from the fire as far away from the food as I can. They all work as they are supposed to, I think some of the commercial pit builders are trying to fix what ain't broke.

[ThinBlue]

On my 3rd build now, and I've put them all as low as possible, and the FB as low as possible to match. I want the radiant heat from the fire as far away from the food as I can. They all work as they are supposed to, I think some of the commercial pit builders are trying to fix what ain't broke.

My understanding is that putting the throat higher and then deflecting straight up in the cc as dacolson has done is supposed to afford you less loss of main grate real estate.

When you build your with the throat at the bottom about how many inches do you sacrifice to a hot spot?

[Back9Q]

Agree with Thin blue. Not sure on how much space is lost going low. I imagine can use Franklin pit as good estimate for that size of smoker with his baffle on far side of pit at grate level


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[ThinBlue]

at least when combined with the massively over-sized firebox.

I think that's one of the keys to that design. Enough space for the air to rise and start swirling before exiting the fb.

Around 4:10 in this video you can see the the smoke is naturally exiting in a swirling motion roughly parallel to the throat opening. The fire is also probably 6-8" away from the door opening. What I'm concluding from that is for their design to work as intended they needed to give the pit master at least a 6-8" air gap between fire and throat in order for it to work as intended. So, just doing the quick math, if they thought someone would use a 16" split + 6" air gap to the throat + at least 2" from the fb door then you have a minimum fb of 24-26" for that design to run properly. Or I could have, and probably did, ccompletely overthink all of it.
https://youtu.be/vvcuR-iWo6I

[SheffSmoker]

On my 3rd build now, and I've put them all as low as possible, and the FB as low as possible to match. I want the radiant heat from the fire as far away from the food as I can. They all work as they are supposed to, I think some of the commercial pit builders are trying to fix what ain't broke.

My understanding is that putting the throat higher and then deflecting straight up in the cc as dacolson has done is supposed to afford you less loss of main grate real estate.

When you build your with the throat at the bottom about how many inches do you sacrifice to a hot spot?

When first built, the beginning 4" of cook rack was way hotter than the rest, after some experimenting with both a downward and upward deflector I added a very rudimentary upward deflector and now it's just the first inch or two that's hotter. Don't mind that though as I use it for crisping chicken up.

After watching that video I can't believe they are asking 3 grand for something still full of manufacturing crap! I wouldn't sleep at night knowing I'd sent out something like that.

[ThinBlue]

After watching that video I can't believe they are asking 3 grand for something still full of manufacturing crap! I wouldn't sleep at night knowing I'd sent out something like that.

I agree. You would think they'd spend a couple minutes after it's built and at least take a hand scraper and a broom to it to. They go for about $1k less than similarly sized pits on the market so I think a lot of folks just accept it.

[Brewmaster]

After watching that video I can't believe they are asking 3 grand for something still full of manufacturing crap! I wouldn't sleep at night knowing I'd sent out something like that.

I agree. You would think they'd spend a couple minutes after it's built and at least take a hand scraper and a broom to it to. They go for about $1k less than similarly sized pits on the market so I think a lot of folks just accept it.

I've seen a few other users videos of Workhorse setup and seasoning but that's the only one I've seen or heard mention of any scale left on. Seems pretty odd.

[Brewmaster]

at least when combined with the massively over-sized firebox.

I think that's one of the keys to that design. Enough space for the air to rise and start swirling before exiting the fb.

For sure!

Around 4:10 in this video you can see the the smoke is naturally exiting in a swirling motion roughly parallel to the throat opening. The fire is also probably 6-8" away from the door opening. What I'm concluding from that is for their design to work as intended they needed to give the pit master at least a 6-8" air gap between fire and throat in order for it to work as intended. So, just doing the quick math, if they thought someone would use a 16" split + 6" air gap to the throat + at least 2" from the fb door then you have a minimum fb of 24-26" for that design to run properly. Or I could have, and probably did, ccompletely overthink all of it.
https://youtu.be/vvcuR-iWo6I

I'm pretty sure that firebox is 27" long. The few times we've cooked on one of these we tried to keep the fire pretty much as close to the door as possible. My thinking is that the whole mass won't be as hot when it enters the cook chamber, making it generally more even-tempered throughout, so to speak. Haven't really had enough time on the cooker to figure out if it might work better or worse with the fire shoved in a bit further though, common sense tells me the closer the fire is to the throat entry, the hotter it'll be, but that could be ass backwards with the ambient air ingress.

[ThinBlue]

You are right on that, Brewmaster. It is 27"... that inch is a freebie.

[Pete Mazz]

I think some of the commercial pit builders are trying to fix what ain't broke.

This.