Please help Stack question

[Bigmark1127]

I am getting tripped up on the stack I have 1718.5 ESV and want to use 4 I'd pipe because that's what I have on hand I come up with 108 inches above the CC I can not find anything if I were to put on two four inch stacks do I just cut the 108 in half??
Thanks for any help

 

[daveomak]

You need an 8" stack 34" above the CC... 2- 4" stacks is equal to 1 6" stack..
Since you are putting a lot of time and money into your smoker, why not get an 8" stack... They make it for wood stoves...

 

[Bigmark1127]

Can you tell me you figure that out so I have the straight in my head thanks for all your help

 

[Bigmark1127]

Sorry the numbers straight in my head

 

[daveomak]

Volume of the CC....
Volume in cubic inches X 0.022 = Exhaust Stack Volume in cubic inches, above the CC.... (ESV)
(The increase in volume ~30% shows a dramatic improvement in equalized temperatures across the cooking surface... edit 6/19/15 )

Exhaust Calculation..

ESV in cubic inches__1718__ ... = Stack Length in inches (36" +/-)
0.7854 X Stack Diameter X Stack Diameter

Adjust the diameter of the stack, until the proper length is achieved... be sure to measure the actual internal diameter of the pipe used..
this is for round stacks only..

1718 / (.7854 x diameter x diameter) = length of stack.... adjust the diameter until you get approx. 36"...

1718/(.7854x8x8) =

(.7854x8x8)= 50.... 1718 / 50 = 34 inches above the CC...

 

[Bigmark1127]

Thank you I understand that but how do you figure for two stacks wouldn’t an 8” be the same as two 4” stacks?? This is where I get confused
Thanks

 

[Murray]

Area of a 4” diameter circle is 12.6 square inches, the area of a 8” diameter circle is 50.3 square inches so two 4” pipes is 25.2 square inches, your half way to the 50.3 square inches.

 

[Bigmark1127]

Ah that makes s sense thank you

 

[daveomak]

Thanks Murray....

 

[Bigmark1127]

Thank both of you guys!