New Build Questions

[Smokinchicken]

Getting started on a 250 Gallon Propane Tank (96"x30") with a Square FB 27"l x 30"w x 24"h and a 6" Chimney 34" Long. Do these figures look about right? How many inches up from the bottom should the BP sit? Intake size? Thanks in advance!

[Squiggle]

There's a pit calculator on the main page that will tell you the right numbers & im sure these guys will check them for you. The BP is generally at the same height as the top of the FB & there is a bunch of throat opening calculators in Pete Mazz's signature (I'm sure he'll be along very soon after checking your numbers, he's a bit of a demon when I comes to numbers)

[Rodcrafter]

Welcome to the crew!


Making memories.

[Pete Mazz]

Your throat needs to be 155 sqin. If you use my throat calc you'll get this:

If you want to use a dam or make a trapezoidal shaped throat, go to my calcs and have at it.

The PitCalc shows 58 sqin for intakes. Best bet is make at least 2 and oversize them a bit as they can always be shut down.

[Rodcrafter]

[Smokinchicken]

Your throat needs to be 155 sqin. If you use my throat calc you'll get this:

throat.jpg

If you want to use a dam or make a trapezoidal shaped throat, go to my calcs and have at it.

The PitCalc shows 58 sqin for intakes. Best bet is make at least 2 and oversize them a bit as they can always be shut down.

Changed the length of FB from 27 to 28. Height of Throat shows to be 8.462. Would this also apply to the BP Opening? My tank has shallow bells.

[Pete Mazz]

Yes. Some start at 100% throat size and make an adjustable plate to fine tune it. Anywhere from 50 to 100%.

[Smokinchicken]

Is there a calculator for determining the BP opening? Is an adjustable plate needed and if so how do you know how and when to adjust? I've run an offset quite a bit but never a RF. Could you explain a little about how the intakes are used. Calculator recommends 58sq so I'm thinking a 3x10 intake on either side of the firebox. I wonder when the smoker gets rolling how much would the intakes be shut down? Would one be closed and the other partially open, etc?

[Dirtytires]

We all remember that fire needs air and fuel to burn. We can't easily remove fuel so we restrict air to keep the fire/heat to the proper size. The more you restrict air intake, the more you choke out the fire. With that said, You Still need enough air to keep your fire healthy and keep air moving within the smoke chamber.

I have a slide on both sides of my firebox and, once at temp, tend to have pretty good luck with about 1/3 open on both of them to maintain temp. It takes a bit of tweaking here and there depending on fuel load, direct sunlight (believe it or not, my smoker hits 130 just sitting in the sun in July!) and food load.

It is recommended to put dampers on at least 2 sides to avoid direct wind (which acts as a fan and feeds extra air) and remember you can use them independently. Sometimes I run one intake closed and the other 1/2 open.

The tighter your firebox is sealed, the better control you will have with the dampers. Leaking air around doors and seams is impossible to control.

[Pete Mazz]

This is from the troublemaker that started this all:

On a small pit like you are talking about, you will not have too many troubles doing that kind of setup. because it is smaller in size it is very forgiving. Now if you were to get into a large pit you may have some control issues depending on your cooking preferences.
I always say "depends on your cooking style"
For starters, Most important thing to remember when you are talking about anything removable in the cook chamber is the grease and juices from the meat. You got to keep them from building up and draining into the firebox which could cause a grease fire.
Next, The tray you are referring to in the cook chamber, we refer to it as the Baffle plate, is used as a heat sync to help even out the temp in the cook chamber. this is done by building up heat and then radiating evenly. If you put water or juice in the baffle plate and fill it up, it will come up to temp gradually but will take a long time to come up to temp once it finally does (212*F at sea level) it will quickly boil off and need to be re filled. once you refill it you will start the process over again and the pit temp will drop a lot. thus you will lose control of the pit. if infact you then forget to fill the pan back up about every 45 minutes or whatever it would take then the pit would run out of water and skyrocket out of control. for this reason I do not recommend using water directly in the plate. Instead, use a pan of water placed on the plate which will produce the same result of more moisture in the C.C. without the other problems.
as far as the Gap in the plate goes, it just depends on the "tune" you want for your cooking style. I design all my smokers at a tune that I feel works best for me. here's a basic run down how it works....
Bigger plate gap= less restriction under the plate=less time the flue products spend under the plate= less heat transfer to the plate.
smaller plate gap = more restriction under the plate= more time the flue products spend under the plate= more heat transfer to the plate.
IMPORTANT= too small or too big of a gap leads to improper combustion on the small side or no control on the bigger side.
WINDOW OF TOLERANCE- big side= size of firebox to CC opening
Small side= size of smoke stack diameter in square inches.

Hope this helps! Did I answer all your questions?

[Smokinchicken]

I'm kinda like goldy locks. I like my just right. Problem is I don't know what is just right. Is there an ideal % of the FB opening that is safe?

[Big T]

I make all of my BP gaps the same as the throat and I've never had any issues. I have never made them smaller than the throat so I don't know if it would perform better or worse than what I've built. I've thought about going a little smaller or building an adjustable BP gap but it already works so well that I didn't want to mess it up. jm2cw

[Squiggle]

I like your style, don't mess with what works for you!

[Frank_Cox]

We all remember that fire needs air and fuel to burn. We can't easily remove fuel so we restrict air to keep the fire/heat to the proper size. The more you restrict air intake, the more you choke out the fire. With that said, You Still need enough air to keep your fire healthy and keep air moving within the smoke chamber.

I have a slide on both sides of my firebox and, once at temp, tend to have pretty good luck with about 1/3 open on both of them to maintain temp. It takes a bit of tweaking here and there depending on fuel load, direct sunlight (believe it or not, my smoker hits 130 just sitting in the sun in July!) and food load.

It is recommended to put dampers on at least 2 sides to avoid direct wind (which acts as a fan and feeds extra air) and remember you can use them independently. Sometimes I run one intake closed and the other 1/2 open.

The tighter your firebox is sealed, the better control you will have with the dampers. Leaking air around doors and seams is impossible to control.

Dude, ya nailed it......
Couldn't said it better
Many beers to ya!

Sent from my SAMSUNG-SM-G890A using Tapatalk

[Smokinchicken]

Thanks guys! You all have been very helpful. Hope to have pictures soon.

[Smokinchicken]

1st build about 15 years ago.

[Smokinchicken]

Another view.

[Smokinchicken]

I wanted a 2" drain with a ball valve but my guys put a 1" drain instead. Will this be sufficient?

[Squiggle]

Ver cool!

Can't see why not, how much oil do you think you'll be producing? Lol.

[Rodcrafter]

The oil won't be a problem but the stuff on the baffle plate isn't all oil. I wouldn't say change it, but you may want to do the cleaning only when it's hot.


Making memories.

[Big T]

I have used 1'' and it can get chunks of burnt grease and meat stuck in the drain. It's not a major deal to run something through it to clean it out but it is inconvenient.

[Smokinchicken]

Update: I work at a prison that has a vo-tech. You supply the material and they supply the labor. They have been working on my new trailer rig for over a month now. I thank all you guys for your input. This is the 3rd build that I have supervised but the first time that I havn't just winged it. The major portion of the build is done and just putting the finishing touches to it which may still take a couple of weeks with their schedule. No cameras in prison but I will have pics in the near future.

[Big T]

We're looking forward to seeing it.

[Squiggle]

[Rodcrafter]

Awesome free help


Making memories!