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jtippers
06-07-2017, 09:00 AM
Hail BBQ Brethren,

First time poster on this forum, so please excuse if this is in the wrong location.

I am in the process of building a new reverse flow stick burner from an old 120 gallon propane tank. I can't seem to find any info concerning the thickness of the heat baffle.

Working with my granddad on the project and he picked up a piece of #10 sheet metal (really thin) and swears it will work... This is the only part of the smoker I am worried about. Am I justified in thinking we needed a much thicker piece of metal, or do you think the 10 gauge will work?

Would like to fix it, if needed, before we start painting and burning it in.

Many thanks in advance!!!

-J

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MisterChrister
06-07-2017, 09:37 AM
That's a pretty friggun cool build there! I agree, that's too thin and will likely burn thru on the firebox end, but I'm no pro. Some of those should be along shortly.

Welocme to the best website on the interwebz!

jtippers
06-07-2017, 10:36 AM
Thanks for the compliment!

My biggest concern is with the metal being that thin it will radiate heat and burn the bottom of whatever I am smoking.

Then again, I could be overthinking... that's why I ask the experts! :D

Zak
06-07-2017, 03:19 PM
That 10 gauge should be .1345" thick and 1/8" is .125" thick so if you think 1/8" thick steel will burn through, you're building way to big of a fire. The problem with reverse flows, as i found out after i built mine, was the radiant heat from the plate under the cooking grates. I've crisped a few briskets by running to hot, which my plate is 1/8" thick and way over kill, but i'm running 325-350. Cooking at temps below 300 then no problems. Even if you put a 1/4" plate in it'll eventually reach a high temp and radiate heat the same way, it'll only take longer to come up to temp and it'll hold that temp longer also.

jtippers
06-07-2017, 03:53 PM
Awesome! That makes perfect sense. I was mistaken earlier when I said 10 gauge, its actually 16 gauge... even smaller!

I'll light it up and smoke a couple of butts to see how it does and watch for hot spots. I don't anticipate going above 275-300, at least not on purpose... :heh:

Shagdog
06-07-2017, 04:38 PM
I would go with 1/4". The radiant heat from 16 gauge is going to make the right side run pretty danged hot. Things in that corner are going to get extra crispy

TuscaloosaQ
06-07-2017, 05:50 PM
I would you 1/4 inch plate... at a bare minimum 3/16... I really would be would not be worried about heat distribution as much as I would be worrying about having to go back in the cooker one day and cut out the baffle plate that rusted thru... go all out the 1st time.... and never look back.... you have way to nice of a build to not go all out on the baffle plate..... 1/4 inch all the way

jtippers
08-17-2017, 11:34 AM
Hey folks!

Thanks for all the awesome feedback on my first question!

After using the smoker a few times, I was having some wild temp swings from left to right inside the cooking chamber with the hotter temps being on the right (firebox/exhaust side). At first, the temp swing was 100+ degrees. After some studying (and drinking) over the problem, it dawned on me that I cut the hole in the firebox on the top and side feeding into the cook chamber.

In that config, the fire was beating directly on the bottom of the heat baffle. I welded the top piece back in and that settled it down to about a 40 degree swing. Is there anything else I can do to minimize this fluctuation?

I am thinking of adding a 2" piece of mineral board on the top of the firebox to further insulate the bottom of the heat baffle where the firebox overlaps it.

The only other thought I have is maybe my exhaust pipe is too tall...

Here are my specs:
120G propane tank
1/4" x 20" x 20" steel fire box (uninsulated)
3/16" Heat baffle
4" exhaust pipe 34.5" tall

Happy to post pics, but I still need to upload them somewhere.

Thanks,
Josh

jtippers
08-17-2017, 11:47 AM
Here we go...

http://i.imgur.com/4d7T409h.jpg

http://i.imgur.com/GNGhajNh.jpg

http://i.imgur.com/hh4pymYh.jpg

SmittyJonz
08-17-2017, 04:06 PM
How big is you end gap on other end.?

jtippers
08-17-2017, 04:42 PM
7" at the widest point... it follows the curve of the tank.

sylntghost
08-18-2017, 05:02 AM
I may be wrong and someone can correct me if so. But I think you could go with a piece of 6 inch pipe as your smoke stack on a 120 gallon tank.

m-fine
08-18-2017, 05:27 AM
If your chimney is less than 50+ feet, it is not too tall. Tall means it drafts better. Too much draft can always be dialed back with your intake baffles. Not enough is a fatal flaw.

It looks and sounds to me like you just need to learn how to manage the fire and airflow for your pit. Try a smaller fire closer to the door so the flames are not licking the RF plate. Adjust your air intakes, never down to the point the fire is choking and smoldering, but maybe dial back some of the fanning of the flames.

If it stays way too hot at the fire box end, try sticking a water pan there under the chimney. Water can absorb a ton of heat out of the RF plate. You can also use it to cool the top of the firebox which can transmit heat to the smoke chamber.

jtippers
08-18-2017, 01:35 PM
If it stays way too hot at the fire box end, try sticking a water pan there under the chimney. Water can absorb a ton of heat out of the RF plate. You can also use it to cool the top of the firebox which can transmit heat to the smoke chamber.


I'll be the first to admit, I'm a novice at cooking with a stick burner...

I had been running the smoker without a water pan every time I tested it. That along with moving my fire to the back of the firebox seems to have done the trick.

One thermometer probe is on the far left of the grate and the other is on the far right.

Have a couple of racks of baby backs on now. Will post pics later when they finish up!

https://uploads.tapatalk-cdn.com/20170818/e8c7a92cbaf45086fec6dd50fcbf8ed0.jpghttps://uploads.tapatalk-cdn.com/20170818/d54159756fb5f812ac5c175ba6ba1ef3.jpg


Sent from my iPhone using Tapatalk

Cook
08-18-2017, 02:45 PM
If your chimney is less than 50+ feet, it is not too tall. Tall means it drafts better.

I am NO pit builder...but I have heard actual pit builders say that if the exhaust pipe is too tall, the temp of said exhaust will cool and fall back down the pipe. Which isn't exactly how you want it to work.

m-fine
08-18-2017, 02:57 PM
I am NO pit builder...but I have heard actual pit builders say that if the exhaust pipe is too tall, the temp of said exhaust will cool and fall back down the pipe. Which isn't exactly how you want it to work.

That is technically theoretically true, but it isn't going to happen on a relatively normal pit. As I said, over 50+ feet tall...unless it is super wide, as in feet not inches.

It only takes a very small temp difference for the air to keep rising and there isn't enough heat loss in a chimney to get from 200+ down anywhere near ambient temp.