# reverse flow help



## Troyb1990 (Apr 6, 2019)

my brother and I just finished our first reverse flow build, and had a small issue while burning it out the first time. 






We couldn't get even temps across the grates. It was running 25 - 50 degrees difference from end to end. Ill add some pics so you can see how it's built.


















Any ideas would be helpful.


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## pineywoods (Apr 7, 2019)

First thing I would try is raising and lowering one end and see what kind of differences that makes


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## Dantij (Apr 8, 2019)

My Lang 48 usually takes about 2 hours before the temps start to even out.  Give it a little time before comparing sides.


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## Nole4L (Apr 8, 2019)

I'll second Dantij.  My Lang likes a little extra time to hit a nice even temp.  The pay off is once that plate gets hot it provides great steady temps.


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## Troyb1990 (Apr 8, 2019)

Dantij said:


> My Lang 48 usually takes about 2 hours before the temps start to even out.  Give it a little time before comparing sides.


We did run it about 3 hours. The closest the temps got was 20 degrees. Maybe my plate isn't thick enough? I think its 11 or 12 gauge.


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## Troyb1990 (Apr 8, 2019)

I was wondering if doing one of the modifications marked in red in this pic would make any difference?


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## flatbroke (Apr 8, 2019)

try placing 3 pieces of foil on the griddle next to the firebox and see if that helps.  Not 1 or 2 pieces,  3 of them.


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## Troyb1990 (Apr 8, 2019)

flatbroke said:


> try placing 3 pieces of foil on the griddle next to the firebox and see if that helps.  Not 1 or 2 pieces,  3 of them.


like 3 thick just on top of the grate?


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## flatbroke (Apr 8, 2019)

Under the grate. On the metal reverse flow plate against where it meets the firebox wall


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## Troyb1990 (Apr 8, 2019)

flatbroke said:


> Under the grate. On the metal reverse flow plate against where it meets the firebox wall


I'll try that next time we fire it.


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## weedeater (Apr 8, 2019)

Couple of things to try:
Put a pan of water up against the firebox end.
Build fire as far away from cook chamber as possible. 
May need more vents on firebox to move more air through the cook chamber.  Vents up high on firebox help to move smoke through without increasing temp of fire.

Don’t give up on it!

Weedeater


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## Troyb1990 (Apr 8, 2019)

I do have 20% of my vents on the top of the firebox, but could easily add more. I did get thinking, that partly it could be we had too big of a fire going. 

I'm not giving up yet! I think we can get it working if we put a little time into it. One thing I do know is that when it's burning it burns like crazy. Sounds like a tiny jet engine in the firebox!


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## hardcookin (Apr 9, 2019)

I would see if the temps even out if your smoking quite a bit of meat.
I would also just keep experimenting until you hit the right combo.


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## Troyb1990 (Apr 9, 2019)

hardcookin said:


> I would see if the temps even out if your smoking quite a bit of meat.
> I would also just keep experimenting until you hit the right combo.


We'll do that! we're new to running smokers so I wasn't even sure where to start!


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## daveomak (Apr 9, 2019)

What temp was the smoker operating at when  the temps were tested ??? 
Is the FB door air tight ???  Is the CC door air tight ??    Did you test with the upper air inlets wide open ???
I need more information....


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## Troyb1990 (Apr 9, 2019)

We tested at a range of temps, mostly in the 230 - 270 average range. We brought it up to about 260 avg, let it set for about an hour, then cooled it down to about 240 avg for an hour. after that we heated up to about 450 for an hour to set the paint on the cook chamber, then cooled it back down

The differences were were consistent at all temp ranges. They started at about 50 then came down to around 30 after about 45 minutes and stayed there except when we were raising or lowering the temps.

The firebox door is a steel on steel seal with the widest gaps being less then a 64th of an inch.(my brother is good with steel!)

We were testing with the upper inlet open. 

Closing the chimney damper a bit seemed to help some, maybe 5 degrees.


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## daveomak (Apr 9, 2019)

Woody has even temps across his RF smoker....  He even smokes cheese in it...  Great temp control...
https://www.smokingmeatforums.com/threads/short-fat-120-gallon-build.238321/page-6





* woodyg Smoke Blower *
Monticello, MN
Smokerbuild said: ↑
Hi Woody, does your smoker have any flap that covers the halfpie cut out in the fire box to control the smoke and heat? I saw one like that. Thanks, Pat

Hey pat. I just wanted to add to my last post. Right now I am smoking some cheese







Now I am truly convinced you don't need a flap or dampener between the FB and CC. It's holding temps steady at 80 deg left to right. I'm a true believer in DaveOmak's calculator.


....


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## Troyb1990 (Apr 9, 2019)

daveomak
 I guess I missed a question in your previous post.

The CC door does not quite seal. It had a lot of spring in it when it was cut and I couldn't get it pulled back down all the way. Once the draft gets going there is only an occasional curl of smoke from the bottom.

I'm trying to decide if I should cut it off and rebuild it, or get some stove door gasket for it.


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## daveomak (Apr 9, 2019)

If you have any air leaks, temp control will be sacrificed...  I would use high temp sealing rope...  for wood stoves...   If needed, cut off the hinges, add the sealing gasket, weld the hinges back on...   they may need adjusting due to the gasket material...  
Looking at the picture of the finished smoker, I don't see the FB upper air inlets...  are they directly across from the FB/CC opening ??  Or are those holes at the bottom of the door your upper air inlets...


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## Troyb1990 (Apr 9, 2019)

We'll look into the door issue.

The upper inlet is directly across from the FB/CC opening.
here's another pic of the firebox door:


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## daveomak (Apr 9, 2019)

Looks good from here....


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## Troyb1990 (Apr 9, 2019)

Well I've learned a lot here, so we'll do some testing and likely some remodeling, and see how things turn out.

Still open for some more ideas if anyone has any!


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## Troyb1990 (May 10, 2019)

Ok, I've done some work and and a bunch of testing and I think I've pretty much got it figured out. 

We sealed around the CC door some more and that didn't seem to make much difference.

I also tried the foil idea that was earlier in this thread, along with replacing the foil with and actual steel plate, neither of which helped at all.

Next I added the baffle in the firebox like in the earlier diagram, and that made a few degrees difference, but made it much easier to control the overall temp.

Then I took a laser temp gun and ran it all over the CC while it was running and discovered that the temps made a pattern like this:







That left 2 options in my mind, raise the chimney or put a baffle in the other end. So I went the easy route and added the baffle, so I now have modifications like the following image:






I am now getting end to end temp differences consistently in the <10* range, with the hot end now being the far end away from the FB.


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## daveomak (May 10, 2019)

Cool....


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## dcrumrine (Jul 24, 2022)

I know this is an old thread but it might help someone else. The problem with this design is the placement of the stack. A reverse flow stack should be placed at the top of your CC. An offset smoker the FB CC opening should be at or just above grate level and the opening should be facing up not out. The collector should be at grate level, built this way it will eliminate the need of a baffle plate. If you build your smoker with the CC FB opening like originally designed coming out the side baffle plates will be needed and you will want to build the collector at grate level. Also something else to make note of, the back wall of your collector should be your stack pipe. This makes for a much smoother transition for the draw to turn vertical up your stack.


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## sacedbysapp (Jul 29, 2022)

Could try using longer splits, not thicker just longer. But 20 degrees id take that and run with it. Maybe use that area for something that needs a hotter temperature like chicken or if you’re running behind on something it’s taking a little longer to cook sometimes it’s not a bad idea to have a little bit of a different time zone to work with.


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