# 24" X 48" RF calculation advice

Discussion in 'Reverse Flow' started by smokingunny, Jun 17, 2014.

1. ### smokingunnyMeat Mopper

Here is my dilemma. I have this grill that is 1/4 X 24 X 48 pipe, cut in half so I'm not sure what the volume is. This makes Feldon's calculator a bit tricky to use. It has no lid so I need to make one and that is my first question. What dimension does the lid need to be? It will obviously be a rectangle, and I was thinking 12"H X 2'W X 4'L.

How big should the fire box be? Thinking about 20" X 20" X 18".

What size should the opening to the CC be? Considered the football shape at 8"H X 20" across.

How far up should the RF plate be, and how big of an opening should be at the opposite end of the plate?

Here are a couple of pics if this helps.

2. ### ribwizzardMaster of the Pit

since you don't have a lid, and have already decided to not use a rounded piece, first step is to locate the material to box in a lid. I would recommend welding the sides, rear and top onto the existing body and do a front opening door with pull out racks. If it was me, id probably use 24" wide 1/2" plate, that will give you plenty of room for three racks and keep the cooker looking symmetrical.

either way, decide how you going to do the cooking chamber , then that will determine what size firebox you will need.

Have fun!

3. ### smokingunnyMeat Mopper

That makes sense but I think I want to stay with a hinged lid so that it can be removed and be used as an open pit if I want to. I work with a guy who also has a bike shop. He estimated materials and cutting, plus tacking it at the proper angles, at about \$165. That also includes the fire box. I can run the beads myself to save costs.

4. ### smokingunnyMeat Mopper

OK, I've managed to make a little progress here. I'm trying to nail down some numbers so that I maybe get it right the first time. I've made a lid out of a 55 gallon barrel that I cut in half, now I just need to seal it with fire place gasket and weld on the hinges. Where I need help is with numbers generated by Feldon's, Link to BBQ Pit Calculator.

Since this is my first build, what are the experts' advice? Do the numbers sound good?

5. ### daveomakSmoking GuruOTBS MemberSMF Premier Member

Have you read on here that Feldon's has some inherent problems....

6. ### smokingunnyMeat Mopper

Yes I have. Is there another calculator or set of formulas that are more accurate?

Last edited: Oct 6, 2014
7. ### smokingunnyMeat Mopper

Would a 6" exhaust be fine? I'm thinking about having it come out of the side of the lid as opposed to the top.

9. ### smokingunnyMeat Mopper

Now that you posted that, I printed that page last night but forgot about it. I'll run some numbers and see what I come up with.

10. ### smokingunnyMeat Mopper

Ok, now that I have my lid made and dry fit I realize that while my cuts may not be the best, the guy who made the bottom part didn't make sure things were square. I had some gaps that were thankfully filled by the fireplace gasket. Still have some fine tuning to do but it will be ok. Finally got to the point where I was ready to tack on the hinges.

This is the rear view, the firebox will ultimately be on the right side from this view.

Last edited: Oct 8, 2014
11. ### smokingunnyMeat Mopper

As it it turns out, these stops that I made from an earlier modification work pretty good for this lid.

Last edited: Oct 8, 2014
12. ### smokingunnyMeat Mopper

I have this old air compressor tank that I was going to make into a grill. Then I thought maybe I'll use it as the firebox on this build. It's 16x25 inches, Feldon's says it's 73% of what it should be. What are your thoughts? If it's too small it's too small. I'm just trying to save a few bucks if I can.

13. ### smokingunnyMeat Mopper

Finally making some progress. Got part of the firebox cut and tacked into place. Hoping to have it done by next Thursday for the unit Christmas party.

14. ### smokingunnyMeat Mopper

Had to stop work due to a plate falling on my toe. Going to get it x rayed today so maybe I can resume.

15. ### smokingunnyMeat Mopper

Managed to get the firebox tacked up. I plan welding the top once it's attached to the CC.

16. ### lendecaturalSmoking Fanatic

Looks good, how is the foot doing?

17. ### smokingunnyMeat Mopper

Sore but better. I'll be posting more pics later.

18. ### smokingunnyMeat Mopper

Firebox is all welded. Here is my diagram for the FB door. The box is 18x24 at this angle and I'm planning on the door being 12x18. Too big or too small, just right? Just want to get the expert advice before I cut.

19. ### smokingunnyMeat Mopper

I guess a pic would help.

20. ### curtisimo81Smoke Blower

Looks good. Can't wait to get mine to the point where your is.  Trying to find a place that will cut mine today but I doubt I'll be able to find a place.lol