First build decagon, center feed, build with plates. Not the normal way.

[etotore]

I have been around for some time looking for any tank, propan, air-compressor not possible to find in my area of the world..
Only offer was an hydraulic oil tank, I polity declined that one.

So I'm making it out of mild steel plates... I don't have a fancy tool room so it will be interesting.
Side drawing of the build I'm making in 1/4" plates..

Length of smoker is 63", I'm a metric guy so please bear with me. So 200 US Gallon did I calculated it to be.
length of FBox is 23" should give 62 Gallon. (Since its center feed it can be 30 % less in size, discovered this after the cutting)
Opening's should be 173 Cuin2 ???

First question is baffle plate distance from bottom any advice. Will probably make this one in SS, since some said it was working very well.
Think it's worth a try. It has 3 times less heat transfer than mild steel, ref table I did find.

Then more heat should be transferred by the smoke, that is a good thing.

Plate usage planning.

[etotore]

FB looks very big, so read a bit more, I can reduce it's size with 30 % since it's center feed?
Think I will reduce internal volume by insulating and making the shape more like a dome internally.

The white line where the arrow pointing too will put a plate there and insulate above, think it will give better chimney effect too.
The internal, the baffle in the middle, is an idea to block direct radiation from the fire to hit bottom plate of the cocking chamber. Will mount a tube/ thin plate box on top of this baffle with a lot of small holes in it, Upper air vent will air into that box, from the side. So its air gets heated and spread out into the whole top chamber. Is a common way in clean burning ovens in Noway. Not sure it will work, worth a try anyway.

Still trying to get the welder right, but its getting there.

Will a 5" hole circular be enough from FB into chamber? Or a square one?? any advice.
Baffle placement still struggling to get grasp on that one.

[towtruck]

I think your on the right track. I would use the calculator to figure out your throat size and exhaust size. Looks good so far!!!!!

[Dirtytires]

Interesting thought on the stainless vs carbon steel. I might argue that, in a smoker, you do not want more thermal transfer on the bottom near the heat source. We like low temps and don’t want to “grill” our meats with direct heat radiation but rather heat up the entire cook chamber as evenly as possible.

Just giving you another view-point. Either way, I’m interested to see how it works out.

[dacolson]

Love the creative approach. I’ve read a bit about high efficiency stoves in Norway. Interested to see how it plays out for you.
Few thoughts:
1. If you put a plate angled across the top of your FB where your white line/arrow is, you will reduce the volume of the FB. Make sure you are watching your volume calculations.
2. On the FB/CC opening, round or square doesn’t matter as long as your area calculations work out.
3. On the baffle plate, I agree w dirtytires - you want it to heat up and spread that heat across the entire CC. I would stick with mild steel In my opinion. For BP placement, most folks aim for about 3” below the bottom cook rack. The BP height above the bottom of the CC is not as important as the gaps between the end of the BP and the end sides of your CC where they constrict airflow. That area can be calculated in the online calculator section - http://www.smokerbuilder.com/forums/vie ... 144&t=5474

Very cool pit build. Looking forward to seeing your progress.

[Big T]

I also think it's an interesting design. The pit calculator doesn't work for a center feed design, it takes into account the heat loss through the top of the FB. On a center feed there's very little heat loss since the throat is at the top of the FB, they're very efficient. This leads to having a very small fire to run the cooker, a lot of guys use charcoal as fuel because it's easier to control. I also look forward to seeing you finish your build.

[tinspark]

I also think it's an interesting design. The pit calculator doesn't work for a center feed design, it takes into account the heat loss through the top of the FB. On a center feed there's very little heat loss since the throat is at the top of the FB, they're very efficient. This leads to having a very small fire to run the cooker, a lot of guys use charcoal as fuel because it's easier to control. I also look forward to seeing you finish your build.

I agree with Big T on the small fire. Here was my center feed build..
https://smokerbuilder.com/forums/viewto ... =11&t=7432
I was given the advice (Big T) to add a slide damper at the top of my fire box, which I did and I am glad i did for several reasons. The first is that I built my first test fire and pegged the smoker at around 500* F. Very hot! That was with only 2 splits and a half of a charcoal chimney full of charcoal. My next fire was only about 10 briquettes and a couple of 6" long splits at about 2" diameter each and I was up to about 350* F with my top damper wide open. I close it to about 1/2" open and managed a small fire and am able to keep as cool as I need to go "low and slow" . A second bonus of the slide damper at the top of my FB to CC is the when I reload it with splits, I can temporarily close the damper all of the way and grab my Dewalt 20V battery shop hand blower and blast the firebox and get the splits raging hot in a matter of seconds, and not worry about shooting ash into my CC. That way I can shut things down and almost instantaneously get the "thin blue smoke" back.
I too like your design. If you look at my FB,I tapered it back to the throat opening size of the RF calculator specs, and kept everything else on the build in the parameters of the RF calculator specs as well, and it works great. I am not suggesting changing your FB-CC opening, but if you have trouble with it (like too much heat) the beautiful thing about metal is that you can always modify things. I like having the throat however between the CC and FB for the reasons mentioned above. I hope that in the end, it cooks the way you want it to..

[etotore]

Thanks for nice words an support appreciated.
Also that I got long and good explanations.

Hot spot is, on my list of things to look into with center feed, with any material, is a problem issue in this design.
Would like to try both mild steel and SS, to compare on the RF baffle. (Tinkering with a dual SS with air gap between, Bottom one horisontal, (equal resistance for flow left, right for smoke) top one shaped with a fall to get dripping away, drain, and so on. If SS 1.4 mm thickness times two it will be equivalent to 9 mm mild steel or 3/8 " in thermal transfer mass, then small air gap will affect thermal, and uniformens of heat transfer, too.) think it's worth a try.

The steel baffle I made inside the FB that blocks radiation waves from the fire to go through the air opening, and block it from hitting the RF baffle is a good first step. Forces more heat to be convection, and conduction through the materials.

I think I will make a little bigger opening between FB and CC, and make a sliding valve to find the sweet spot for air opening, between chambers afterwards. Possibility to close it I did not think about, great point. Since the mathematics for center feed is not invented yet, still volume vs fire should have some correlation in all designs, as you confirm.

Will have little less than 6" in distance from RF to the bottom plate, is to big distance compared to calculations. I know, but easy to implement. Then adjust airflow in area at the end of the RF plate, use the calculated value as a proven starting point. So I create an "over-pressure zone" below RF plate. See any issues with that approach??

Feedback is always welcome, today I was working in the push cart for the Smoker.

[etotore]

Love the creative approach. I’ve read a bit about high efficiency stoves in Norway. Interested to see how it plays out for you.
Few thoughts:
1. If you put a plate angled across the top of your FB where your white line/arrow is, you will reduce the volume of the FB. Make sure you are watching your volume calculations.
2. On the FB/CC opening, round or square doesn’t matter as long as your area calculations work out.
3. On the baffle plate, I agree w dirtytires - you want it to heat up and spread that heat across the entire CC. I would stick with mild steel In my opinion. For BP placement, most folks aim for about 3” below the bottom cook rack. The BP height above the bottom of the CC is not as important as the gaps between the end of the BP and the end sides of your CC where they constrict airflow. That area can be calculated in the online calculator section - http://www.smokerbuilder.com/forums/vie ... 144&t=5474

Very cool pit build. Looking forward to seeing your progress.

The high efficiency is actually easier to design on a normal reverse stack, also is against smoke, since it does make the burn more clean,
I think I will keep it closed in the first 3-4 hours and use it in the later parts of the smoke or maybe it has to small heating plate, to actually work.

1. Aware of that, read on some forum that FB can be up to 30 % smaller on a Center feed design because of the efficiency so it will go from 188Gal/62 FB to 188Gal /45 FB.

2. Will make it too big, and have a sliding plate for adjusting, blocking.. For flexibility.

3. Thank you, it confirms the end gap is the most important part of the RF plate.. makes me happy.

[dacolson]

How’s the fab work coming? It’s obvious you’ve got a lot of thought and math/engineering into this. It would be interesting if you can get some predictable math on volume calculations out of your upfront work when it’s done and tested.

[etotore]

How’s the fab work coming? It’s obvious you’ve got a lot of thought and math/engineering into this. It would be interesting if you can get some predictable math on volume calculations out of your upfront work when it’s done and tested.

Hi
Working with it every day, don't have a fancy work place so, last days I'm building the push cart for it.
Before it gets to heavy to man handle. Happily stuck at home until further notice due to Covid, travel restrictions.

I will do measurements myself, very interested in how different settings will affecting smokers operation, meats final results.
Since FB/CC will have a sliding valve between them that adjustment is easy, to measure changes with. As long as I know the opening size.
Maybe use a gas burner for testing and some smoke chips to get uniform energy between different baffle test, and openings?
Any test meteorology you can think of? Is a few weeks to go still.

[dacolson]

It would be interesting if you could increase/decrease the volume of the FB in addition to the size of the FB throat. Use fire bricks or something you can add or remove.

[etotore]

Will try to do it.
A way to check for issues, guess it takes long time between adjustment and results.

[etotore]

Made a sliding Throat adjuster:

I can see on the welding drops I have made, how many inches wide the opening is.
So I have sort of good control over throat opening, 6 inches wide and max length is 10,5"
Think I will need to reduce the size of opening when I find out my operating area.

Sliding doors, first Tig splatting around in 30 years.

Temporary handle, but it show the opening size.
After I had done it, I found out how I will make it later.

open

Since is symmetrical in the way it's opening from center it don't favor any side left/right.

[tinspark]

Wow, very good. Never seen that one before! How thick did u go on the sliding dampers?
Also, it looks like it may be possible to replace those relatively easily. I went 1/4" on my throat damper.
I close mine all of the way down when I add wood and use a small battery leaf blower to get the logs going then open the damper after I close the FB door. Keeps ash from getting into the CC and gets splits going in seconds. Also it is necessary in order to keep the heat from spiking. You may find that you only need a very small fire during cooks, which saves a bunch of wood...

[etotore]

Sliding dampers are 1.5 mm SS, so they not so easy get stuck by rusting into plate below.

Thanks for nice feedback, tinspark

[etotore]

Been tinkering with Center feed temperature calculations, benefit and negative sides.
Good with a challenge from Dacolson,

Warning long post..

I'm not a thermal engineer or any expert into this, so please comment and correct me.

There are three types of heat, since English is not my first language.
Use Picture:

Types of heat

Direct radiation from fire should not reach Baffle/RF-plate, since I see a problem with hot spot. Shadow plate mounted in top of fire chamber. So as much heat into smoke as possible, better control. There will go much more heat into convection, moving through the metal like an oven, from firebox and into the cooking chamber, also from the hot smoke under Baffle/RF will add to this.

Resistance on air under the RF-plate will be less, than conventional side mounter fire chamber. so smoke will be hotter, so less airflow is will be needed, / less BTU in the fire. Less air movement. (Some owners of center feed says more moist in products on center feed BBQ, could make sense, less drying out because of less airflow needed.)

Since air has less resistance in center feed configuration, shorter distance, parallel distribution under RF plate, I think I will aim for an over-pressure under RF plate.
So I will be forcing the speed of the smoke to be higher when entering Cooking Chamber. That will be low pressure compared to below RF. That will give more control over equal flow (Left/Right), also more throw, increase smoke spread into the chamber.

Think in that way Conventional Reveres-flow calculations often using same openings all the way.
Same area under RF plate, same opening in the end, going into chamber and often smaller throat.
Think that approach is not the best for Center feed. If you have over pressure under RF plate draft will be not a big issue.

Stolen some ideas for this not really only my tinkering. See references below.

So my 5 cents
Area under RF plate should be big enough, and give equal air resistance in left and right direction.
Opening from FB to CC should be able to control opening size until Sweet spot is calculated/estimated, my guess is less opening than normal reverse flow. I have made a 6" * 11" troth hole that I can symmetrically change opening size on, also I know from the handle position how much opening I have on any given time.

My idea for where will try to focus is to make a narrover opening into CC chamber.
Like a venturi jet or similar to https://desora.co/projoe/
So tune the opening and shape to maximize taste, and control.

As an idea, I will make holes in baffel/RF plate until maximum temperature I can get with a proper fire is approx maximum 250F-300F (150C) in Cooking chamber. That will be my low and slow setting.
Then have an ekstra door/valve for making bigger opening to go high and hot. (Bread/pizza/pate)

Maybe this is not the right Idea, but I need to do something in the Corona time..
Will post here while I'm playing with it, still a few weeks to go before first fire.

References:
https://desora.co/projoe/
https://www.bostonglobe.com/metro/2015/ ... ost_Viewed

Luckily I can borrow some helping tools. My two dogs

[dacolson]

Haha. Good looking dogs.

This is awesome. I love the approach. The symmetrical sliding throat cover is a great idea! I like the thought you have put into different types of heat transfer as well. I’m excited to see some data!

[Big T]

Nice work!

[etotore]

Little bit progress today to.
Insulated with 1" rockwool the front plate.

[dacolson]

[towtruck]

Looking good!

[etotore]

Today it looks more like a smoker.

Little bit late so, bit dark.

Added a better daylight Picture.

Day time

[dacolson]

[Big T]