damper question

[smith54]

hello, 1st post so please bear with me. ive been designing my 24"x48" offset as per the calculator.my firebox is 20" x 24"L. It calls for approx (1) 6" round opening for intake air.this means i will need to make 2 intakes on the front of my firebox 6" round w/dampers? i also read here that these dampers are closed almost all the way most of the time while cooking?Do i actuallty need all of this intake air once the fire is started.I guess what i'm thinking is that if i start the fire with the door open the do i still need both these dampers/intakes? i want to keep the intakes low,near the fire grate so i have somewhat limited space for both. Also ive read that i should always keep the stack damper all the way open and never shut it? is the damper just for rain during storage outside? sorry for the rambling!

[k.a.m.]

smith54, I am guessing you mean two 3" intakes to equal the the one 6". to answer your question yes in my opinion you need all your intake because those numbers give you the flexibility of multiple intake settings for different scenarios such as weather and seasons. I do not know where you read that the intakes on an offset run mostly closed unless that statement was for a particular cooker in question. Most offsets run with at least 1/2 the intakes open to breathe. I would not depend on my door to adjust air intake you will be dissatisfied with the erratic temps it causes. If your planning on a top load firebox you can do a slide damper like the ones I use it gives you somewhat infinite settings. Here is a pic.


As far as the exhaust damper yes on most offsets the damper is for when the cooker is not in use to keep out weather and critters.
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Always remember slow and steady wins the race.

Hybrid Cooker

[smith54]

thanks so much for the info!another question is on the opening to the cooker from the fb.i have the (sq. in") figure from the calculator ,but laying out the arc and figuring sq. in? i failed trigonometry.seems with a square firebox its pretty straight forward,the size of the opening.i just want to make sure its large eough.if it is oversized are there any problems? Not sure if this should have been a new post,or is a continuation ok? tahnks
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inprogress 24 x 48 offset

[smith54]

Kam, what size is the smoker in the picture? i like the dual stacks at grate height!
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inprogress 24 x 48 offset

[k.a.m.]

smith54, your doing fine with your posts. Keeping it together is less confusing. The cooker in the pic is a 24" x 36" with a 18" x 24" firebox.
Here is a link to the build.
http://www.thesmokering.com/forum/viewtopic.php?t=17781

I ran your numbers and if I read your dimensions correctly the calculator called for a 60.29 Sq.in. opening. A half moon 12.5" x 6 1/4" will give you an opening of 61.36" Sq.in. Once cut out this will increase a bit and allow for a 1" bridge at the bottom to keep grease from entering the firebox.
_________________
Always remember slow and steady wins the race.

Hybrid Cooker

[smith54]

ok, got it. i'll post pics(and more questions) as i progress.Great forum!
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inprogress 24 x 48 offset

[GreenSmoker]

K.A.M. knows his HALFMOONS like no other ringer.

(quote)"I ran your numbers and if I read your dimensions correctly the calculator called for a 60.29 Sq.in. opening. A half moon 12.5" x 6 1/4" will give you an opening of 61.36" Sq.in. Once cut out this will increase a bit and allow for a 1" bridge at the bottom to keep grease from entering the firebox.[/quote]"

As to the intakes, on my little beast with an oversize fb, of the 6 4 inch diameter openings, I start with 4 wide open and in a few minutes it is down to the front at 1/2. After I load up the racks they are shut to a sliver and seem to stay at 250ish quite well.

You can see the hole size and in the 2nd pic, the 2 in the door are open about 1/2 an inch on both. With 6 holes as Kevin says, you have options for wind or cold days etc..




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GreenSmoker / Steve C.
Little Johnny says "I like the way you're thinkin'."

Homemade Offset 30 x 30
UDS
Rocket Stove
Liar #92 or is that my age or my IQ or my shoe size or the sum total for all of them?

[smith54]

K.A.M. in regards to your slide damper on your front load 36".I love that it draws air directly under the fire. Seeing that the height graduations are preset by the teeth on the arm ,does it still allow you to "dial in" your temp as well as the old school round dampers?Greenegg mentioned his dampers open a "sliver"?
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inprogress 24 x 48 offset

[k.a.m.]

smith54, while the sawtooth is not as precise as a spinner in graduations I set them at 1/2" increments and have no problem dialing the cooker in.
_________________
Always remember slow and steady wins the race.

Hybrid Cooker

[smith54]

ok thanks K.a.M., Sawtooth it is.
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inprogress 24 x 48 offset