short & fat reverse flow build.

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jcrazyjj

Newbie
Original poster
Feb 4, 2019
8
2
long time lurker on this site, first time builder. i picked up a 120 gallon tank a couple weeks ago and have been slowly pecking away at it as time and money allow.

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I'm curious as to the pros and cons of these two types of exhausts. I think I like the looks of the 90 bend ones more than the plenum but if it makes a negative change in the performance, than I can get over the looks real quick.
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Got the firebox all welded up and the FB/CC opening all cut out. Temporary legs welded on so I can work on it at a comfortable level and not all hunchbacked. Reverse flow plate in and welded, got smart on fume evacuation while welding inside the tank. Found out that a friend of a friend has a CNC plasma table, so I used that connection to cut out the handle brackets and inner door braces which saved me a ton of time and frustration. Lastly, built a wood rack to start drying.
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Reactions: Mad Jack
It looks like the the short fat tank makes it easy to work inside. Looks great!
I love the cnc details.
 
Got the last side of the firebox welded on, door cut out, hinges welded on, grate in. I am one step closer to getting my garage back.

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Looks good! I'm finally picking up a 125 gal vertical propane tank today. What size did you make you FB/CC opening? Did you use feldons calculator for this build?
 
Looks good! I'm finally picking up a 125 gal vertical propane tank today. What size did you make you FB/CC opening? Did you use feldons calculator for this build?

I did use feldons as a rough estimate. I think I ended up with about 100sq in for the opening. 24x24x24 firebox.
 
Got my drain in, latch on, stack up, everything mounted to the trailer and first burn in complete. We're getting real close to cooking time.

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OK guys, I got this thing all finished up and have been using it every chance I get. But, I have concerns. I'm not sure if it's a draw issue or a poor door location but, whenever I have the firebox door open more than a couple inches, which if we're being honest is only when I am tending to the fire. I get smoke billowing out the door. I also have a temp difference of 40* across the grate, obviously higher on the fireside. It is a 120 gallon, reverse flow, non-insulated, firebox is 150% over-sized according to Feldons, 110cu in throat, 110cu in under rf plate, 110+cu in rf plate opening, 6"x44" stack. Lastly, I swapped out the firebox grate for a sheet of 1/2" plate because my coals were falling through the openings. Mind you, everything is welded into place now so there is very little I can easily change but just to know for nest time would be great.

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OK guys, I got this thing all finished up and have been using it every chance I get. But, I have concerns. I'm not sure if it's a draw issue or a poor door location but, whenever I have the firebox door open more than a couple inches, which if we're being honest is only when I am tending to the fire. I get smoke billowing out the door. I also have a temp difference of 40* across the grate, obviously higher on the fireside. It is a 120 gallon, reverse flow, non-insulated, firebox is 150% over-sized according to Feldons, 110cu in throat, 110cu in under rf plate, 110+cu in rf plate opening, 6"x44" stack. Lastly, I swapped out the firebox grate for a sheet of 1/2" plate because my coals were falling through the openings. Mind you, everything is welded into place now so there is very little I can easily change but just to know for nest time would be great.

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I’m a newbie at this but have been reading everything I can here before starting my own build, but hoping I can help anyway. Your fab work and welding looks awesome too, you did a beautiful job!

One idea would be to add upper air vents to the fire box, seems to help with more even CC temps and I believe the idea is to get airflow coming across the firebox without adding more airflow under the fire and making more heat.

But looking at the pictures, I didn’t see any air vents in the fire box at all? I might be missing something obvious, it’s hard to see all the sides. If so, adding air vents would probably be the first place to start. Based on the calculator on this site and your specs I think it would work out to ~6 sq in for an upper FB air vent directly across from the opening to the CC and another 22 sq in of air vents at or below the fire grate.

Hopefully you get it working the way you want it to, I’m still on the hunt for a tank and looking at 120 gal vertical tanks too.
 
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Here's woodyg's build.... He used our tutorial on building a RF smoker....

 
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