Conflicting calculations??

[bbqfoodexpress]

Hi,
In preparations of my build I am doing the required calculations. Now I am lost on how to calculate the CC/FB opening. According to the tutorial it should be 28814 Inch³x 0.004=115 Inch² based on the volume of my CC. However on the online smoker calculator (http://feldoncentral.com/bbqcalculator.html) it should be 0.008 of the size of my firebox... 85.18Inch²

That is a difference of 35% and more than 1 inch of the height of the halfmoon opening.

What to do??

Best regards,
Ron

 

[civilsmoker]

The tutorial has been modified based on many builds to provide for a more versatile smoker. If the CC/FB opening is too restricted then you won't be able to reach higher temps in the CC. This extra area that translates through the full smoke is more forgiving for the losses that happen and such as the actual flow can be controlled by the intake air.

Having slightly larger FB and less friction in the smoke path are all things that add to functionality. If the FB is too small or the CC/FB opening is restricted there is nothing that can be done to over come the losses do to the provided area.

I would recommend you follow the tutorial all the way through the smoker for sizing.

 

[daveomak]

Reading the tutorial, Feldon's has a few flaws... We worked out the problems and built the tutorial....
Feldon's bases it's numbers on the size of the FB...
The tutorial is based on the size of the CC....
The tutorial will build you a great smoker...

 

[Ringer]

I used the tutorial, 100% wouldn't change a thing

 

[bbqfoodexpress]

Thanks all,
I will stick to the tutorial then :-) It means a bit less space for the foodgrids but the flow en temperature control is more important.
My lower grid will be approx. 4 inches above the RF plate. will that be to close burn risks during low n slow sessions?
Ron

 

[JckDanls 07]

Ron... 4"will be ok.. I built mine exactly as the tutorial ... Works like a champ... cruises right along at 225 with the intake only open about a quarter of inch ...

 

[daveomak]

Thanks all,
I will stick to the tutorial then :-) It means a bit less space for the foodgrids but the flow en temperature control is more important.
My lower grid will be approx. 4 inches above the RF plate. will that be to close burn risks during low n slow sessions?
Ron

The upper air inlet on the FB, moves heat from the FB to the CC.... If you run the smoker with the upper air inlets open, you will not have a hot spot and you will have more even temps across the cooking grate....

 

[bbqfoodexpress]

The upper air inlet on the FB, moves heat from the FB to the CC.... If you run the smoker with the upper air inlets open, you will not have a hot spot and you will have more even temps across the cooking grate....

Yep I definitely will have an upper airinlet in opposite of the CC/FB hole... I wish I knew this when building the locomotive.... but maybe some modifications will happen lateron in the future
Thanks,
Ron

 

[ahumadora]

Don't bother with Dave's idea of upper and lower inlets. It doesn't work. FYI. I have built over 1000+ pits to date and don't use a a calculator. Fire box to cook chamber needs to be as large as you can reasonably make it.

 

[daveomak]

LOL... Morning Ahumidora... What's up in Argentina.... Good to see you on the forum...
Sounds as if you are doing well...
Looks as if you are doing well...

 

[daveomak]

Short/Fat 120 Gallon Build

Had a great day today! After doing a couple small little jobs on the smoker I decided to fire it up. I started with a chimney of charcoal. Once that was going I added 3 small splits of wood. It came up to 200 and just stayed there. They were small so I added 2 more and closed my intake about...

www.smokingmeatforums.com

 

[JckDanls 07]

ahumadora ... glad to see ya back... always enjoyed your builds ...