New Build: MMP2

[massive meat pipe]

Well, here we go! Could use some help and experience on this one, I think I may have sized the fire box too small. Fire box is 24X24X24 (13824 CuIn). Cook chamber is a model 288 propane, probably around 250 gal after modifications, so (57751 CuIn) Rule of thumb seems to be the fire box at 1/3 size of cook chamber, I'm a bit off. Think it will be ok? Air intakes are set up at 40 SqIn. Stack is 5" diameter sprinkler main, have 5' of it so I can adjust height. FB to CC I have speced at 120 SqIn, (but can still be adjusted), and the reverse flow opening I have speced at 150 SqIn (and can also still be adjusted). The issue I have...is I have already made the fire box. Which still looks huge, even for a 250 gal tank. But, thought I had better check with you all. So, here are some pictures of the beginning of MMP2!

Thanx!

[Mikey]

http://www.feldoncentral.com/bbqcalculator.html

[massive meat pipe]

Thanx Mikey. According to that site, I'm within 90% on the FB, and the rest looks spot on, so I can live with that!

[curious aardvark]

Insulate the firebox and you're sound

The reason fireboxes are usually so big is that 75% of their surface area radiates heat, so you lose a helluva lot. Insulate it and you lose none :-)

[dsgarner06]

Damn man you got some skills! I wish I could weld like that... the last time I welded anything it looked like crap! I agree with CA on insulating the firebox... it will help in reducing radiant heat, plus burn a heck of a lot more efficient, thus reducing fuel usage. Are you going to make it an offset or reverse flow? Looks like you are off to a great start!

[Mikey]

Thanx Mikey. According to that site, I'm within 90% on the FB, and the rest looks spot on, so I can live with that!

Just curious as to how you determined the size of your chamber and in regards to insulating your firebox, I'm not sure how rough your Winters are in the part of Oregon that you live. It looks like the firebox material is 3/8" which should be fine. Is this smoker going on a trailer or on your patio

[massive meat pipe]

Damn man you got some skills! I wish I could weld like that... the last time I welded anything it looked like crap! I agree with CA on insulating the firebox... it will help in reducing radiant heat, plus burn a heck of a lot more efficient, thus reducing fuel usage. Are you going to make it an offset or reverse flow? Looks like you are off to a great start!

Thanks dsgarner! I am an amature welder, only thing I welded before this was MMP1, an over under 55 gallon drum smoker. But, I wired a shop for a buddy of mine and he gave me a key to it in return! It will be a reverse flow, modeled after a Lang, but I plan on putting a baffle near the front to direct smoke and heat down so as not to pass up the bottom rack. I had not planned on insulating the fire box, but it is a good idea. I will not insulate it yet (as in this year), as I plan to add a warmer next summer. Thank you for the info and kind words!

[massive meat pipe]

Just curious as to how you determined the size of your chamber and in regards to insulating your firebox, I'm not sure how rough your Winters are in the part of Oregon that you live. It looks like the firebox material is 3/8" which should be fine. Is this smoker going on a trailer or on your patio

Hi Mikey, I determined the size reverse of that, fire box sized on capacity of chamber, trying to use the 1/3 method. But, where I'm at you cant be picky about what tank you can come up with, so the tank size changed when I went to pick it up, so its what I have to work with. The sheet stock used for the FB is 1/4" mild steel plate. Looking at a Lang Model 60, he uses a 20" square FB for a 60" X 30" chamber, so I'm optimistic my 24" should be ok. Insulating the FB I did not plan on, but am definitely going to consider it. As you can see from the previous reply, would be done secondary to completion. Winters here are not too bad in the Portland Metro, mild snow maybe once a year. After inspecting the 288 tank, it looks to be closer to 3/8" thickness, so that may help as well. Thank you very much for the input, I do appreciate it. Any other suggestions most definitely welcomed!

[massive meat pipe]

Oh yeah, forgot to add: Will be trailer mounted, no way I'm gonna try to drag this beast around by hand. The tank alone is just under 1000 lbs. Have a boat trailer I'm cleaning up to set it on.

[massive meat pipe]

Best way to install the clean out?

What do you all think is the best way to install the clean out on a reverse flow? To the baffle or the bottom of the CC? See the attached picture.

Thanx!

[Mikey]

That would be the grease drain and the top pic is the one you want.
You don't want any grease running back towards the firebox as you'll have one helluva grease fire if it does.

[massive meat pipe]

Update, paint removal has begun, steel is in way better shape than I could have hoped.

[Mikey]

Looking good...so far

[massive meat pipe]

Bout 2/3rds done stripping paint, but I think the progress speaks for itself. Will be 2 weeks before i have time to finish. Makes me sad!

[massive meat pipe]

Lil help?

Alright, finally got the tank stripped, all ready to layout and cut. This is what I came up with for grill rack layouts, reverse flow plate, and door opening. What do you all think? I would appreciate the input.