New reverse flow build

All the calculators you'll need to design your own smoker.
User avatar
Big T
Moderator
Moderator
Posts: 5534
Joined: September 1st, 2013, 2:40 pm
Title: Go Getter
BBQ Comp Team Name: Backyard Boys
Location: Lower Alabama

Re: New reverse flow build

Post by Big T » August 18th, 2018, 8:32 pm

I think most of us are always thinking about what to do on the next build.


Measure Twice.....Cut Three Times.

User avatar
The Czar
Founder
Founder
Posts: 8334
Joined: May 22nd, 2011, 9:30 am
Title: Spam Hammerer
BBQ Comp Team Name: Team SmokerBuilder- Competition BBQ Team
I'm Certifiable
Location: Missouri

Re: New reverse flow build

Post by The Czar » August 19th, 2018, 6:59 am

That is a neat patio smoker and you did a super job...now for the meats!!! Be like Arby’s!!!!


Sent from my iPhone using Tapatalk Pro


If you can't fix it by sheer force or cursing......then it can't be fixed.....


AKA= The Czar

Blondy_UK
Just Got in trouble for buying tools
Just Got in trouble for buying tools
Posts: 39
Joined: June 15th, 2018, 4:07 am

Re: New reverse flow build

Post by Blondy_UK » August 20th, 2018, 3:31 am

Thanks, that was last years build i made before i found that there were calculations involved. It takes constant tending to the fire box to keep temps stable hence the new build this year.



Chromeski
Expert
Expert
Posts: 472
Joined: July 20th, 2018, 6:59 pm

Re: New reverse flow build

Post by Chromeski » August 20th, 2018, 11:44 am

Coming along very nice. You may be able to fix last year's build still just go over the numbers and see what's missing.



User avatar
Rodcrafter
Moderator
Moderator
Posts: 8455
Joined: July 21st, 2012, 5:46 pm
Title: Member
BBQ Comp Team Name: Not competing yet...
Location: Orlando, Florida

Re: New reverse flow build

Post by Rodcrafter » September 3rd, 2018, 10:38 am

Heck yeah


Making memories!


Current Smokers: Backyard RF Offset and Hybrid RF Offset trailer rig with Cowboy cooker and fish fryer, always room for more........

Blondy_UK
Just Got in trouble for buying tools
Just Got in trouble for buying tools
Posts: 39
Joined: June 15th, 2018, 4:07 am

Re: New reverse flow build

Post by Blondy_UK » September 6th, 2018, 6:38 am

I have taken quite a bit off of the chimney stack but its still a chore to use.
Not done much to the new one lately but doing some this afternoon so will keep you updated with pics later.



User avatar
Rodcrafter
Moderator
Moderator
Posts: 8455
Joined: July 21st, 2012, 5:46 pm
Title: Member
BBQ Comp Team Name: Not competing yet...
Location: Orlando, Florida

Re: New reverse flow build

Post by Rodcrafter » September 6th, 2018, 9:15 am

Blondy_UK wrote:
August 20th, 2018, 3:31 am
Thanks, that was last years build i made before i found that there were calculations involved. It takes constant tending to the fire box to keep temps stable hence the new build this year.


What are dimensions of the older one let's take a look at it.


Current Smokers: Backyard RF Offset and Hybrid RF Offset trailer rig with Cowboy cooker and fish fryer, always room for more........

Blondy_UK
Just Got in trouble for buying tools
Just Got in trouble for buying tools
Posts: 39
Joined: June 15th, 2018, 4:07 am

Re: New reverse flow build

Post by Blondy_UK » September 6th, 2018, 2:14 pm

I will go get the dimension tomorrow and post.
I have made the door for the new one today and fitted the air vent in the front.



User avatar
AndrewPalmer71
SmokerBuilder Addict
SmokerBuilder Addict
Posts: 159
Joined: December 29th, 2016, 2:54 am
Title: SmokinAddict
BBQ Comp Team Name: Not competing yet...

Re: New reverse flow build

Post by AndrewPalmer71 » September 6th, 2018, 3:26 pm

On the old one, I bet the FB to CC dimensions are a bit small.

Sent from my SM-J727V using Tapatalk




Blondy_UK
Just Got in trouble for buying tools
Just Got in trouble for buying tools
Posts: 39
Joined: June 15th, 2018, 4:07 am

Re: New reverse flow build

Post by Blondy_UK » September 6th, 2018, 3:26 pm

Some pics of the door.ImageImageImageImageImageImageImage

Sent from my CLT-L09 using Tapatalk




Blondy_UK
Just Got in trouble for buying tools
Just Got in trouble for buying tools
Posts: 39
Joined: June 15th, 2018, 4:07 am

Re: New reverse flow build

Post by Blondy_UK » September 6th, 2018, 3:28 pm

AndrewPalmer71 wrote:On the old one, I bet the FB to CC dimensions are a bit small.

Sent from my SM-J727V using Tapatalk
Do you mean the throat or rf plate or both. I will try to measure tomorrow if i get time.

Sent from my CLT-L09 using Tapatalk




User avatar
AndrewPalmer71
SmokerBuilder Addict
SmokerBuilder Addict
Posts: 159
Joined: December 29th, 2016, 2:54 am
Title: SmokinAddict
BBQ Comp Team Name: Not competing yet...

Re: New reverse flow build

Post by AndrewPalmer71 » September 6th, 2018, 5:28 pm

I meant the throat. But im taking a wild guess. Upload your measurements and RC and the others will give you some good advice.

Sent from my SM-J727V using Tapatalk




User avatar
Big T
Moderator
Moderator
Posts: 5534
Joined: September 1st, 2013, 2:40 pm
Title: Go Getter
BBQ Comp Team Name: Backyard Boys
Location: Lower Alabama

Re: New reverse flow build

Post by Big T » September 6th, 2018, 5:48 pm

Nice work on the door :kewl:


Measure Twice.....Cut Three Times.

User avatar
ajfoxy
Expert
Expert
Posts: 2170
Joined: April 12th, 2016, 8:07 pm
Title: Neophyte Smoker Bldr
BBQ Comp Team Name: Not competing yet...
Location: Brisbane, Queensland, Australia

Re: New reverse flow build

Post by ajfoxy » September 7th, 2018, 6:17 pm

:yth: very flash.


Learning generally boils down to "Repetition or the avoidance of pain", some people learn by doing, some by watching and some just have to pee on the electric fence.

Whether you think that you can, or that you can't, you are usually right. Henry Ford

User avatar
Rodcrafter
Moderator
Moderator
Posts: 8455
Joined: July 21st, 2012, 5:46 pm
Title: Member
BBQ Comp Team Name: Not competing yet...
Location: Orlando, Florida

Re: New reverse flow build

Post by Rodcrafter » September 8th, 2018, 7:25 am

Very nice work on the door.

On the topic of the older build, It has been my experience that on an offset the FB needs to be tall enough to allow the wood burning fire to have the room it needs to burn correctly. I mean we know that most of the heat comes from the coal bed. But to make more coals from wood it takes very dry wood and small enough fire to burn thoroughly.

The next thing that comes to mind is it seems to have a better draft when the air doesn’t have to make too many turns. Example the air coming from the FB going through the throat with the opening placed where yours is has the air coming out of the throat at an angle then moving across the baffle plate. I would be willing to guess there’s a very hot spot on the FB end.

Gizmo was working on determining the temperature in the FB and under the BP to compare to the CC temperature. I say that to say each transition takes a toll on temperature. The same as turbulence in air flow.

Ok I will drink my coffee now.


Making memories!


Current Smokers: Backyard RF Offset and Hybrid RF Offset trailer rig with Cowboy cooker and fish fryer, always room for more........

Blondy_UK
Just Got in trouble for buying tools
Just Got in trouble for buying tools
Posts: 39
Joined: June 15th, 2018, 4:07 am

Re: New reverse flow build

Post by Blondy_UK » September 9th, 2018, 6:51 am

Rodcrafter wrote:Very nice work on the door.

On the topic of the older build, It has been my experience that on an offset the FB needs to be tall enough to allow the wood burning fire to have the room it needs to burn correctly. I mean we know that most of the heat comes from the coal bed. But to make more coals from wood it takes very dry wood and small enough fire to burn thoroughly.

The next thing that comes to mind is it seems to have a better draft when the air doesn’t have to make too many turns. Example the air coming from the FB going through the throat with the opening placed where yours is has the air coming out of the throat at an angle then moving across the baffle plate. I would be willing to guess there’s a very hot spot on the FB end.

Gizmo was working on determining the temperature in the FB and under the BP to compare to the CC temperature. I say that to say each transition takes a toll on temperature. The same as turbulence in air flow.

Ok I will drink my coffee now.


Making memories!
Thanks, the old cc was a 47kg propane tank 43"*15" and the fb was a smaller gas tank (19kg i think) 24"*12" with rugby ball shaped throat 8"*5". Tha throat is at an angle to the bplate so there is a hot spot at that end, the stack is 4" diameter and 8" from the top of the cc, is was a lot longer before i cut about 14" off.


Sent from my CLT-L09 using Tapatalk




Blondy_UK
Just Got in trouble for buying tools
Just Got in trouble for buying tools
Posts: 39
Joined: June 15th, 2018, 4:07 am

Re: New reverse flow build

Post by Blondy_UK » September 9th, 2018, 6:56 am

Old model.ImageImageImageImage

Sent from my CLT-L09 using Tapatalk




User avatar
Dirtytires
Expert
Expert
Posts: 2183
Joined: November 24th, 2015, 12:36 am
Title: It ain't broke...yet
BBQ Comp Team Name: Dont compete...cook for events once in a while
Location: Phoenix, Az

Re: New reverse flow build

Post by Dirtytires » September 9th, 2018, 3:04 pm

I’m going to take a stab at this...

I ran the numbers and you are pretty close on firebox size. Your firebox is at 107% and normally I would feel that is fine but on a long horizontal firebox a much greater volume is taken up below the grate. And tho you probably just cooked with it, it also appears much of the space below the grate is full of ash further decreasing the volume. On that type of of a firebox, I might suggest switching to a lump charcoal instead of wood as it tends to burn cleaner and needs less volume (in my experience, at least). I might also experiment with keeping the fire to the far right and away from the cook chamber as much as possible. If you decide to go charcoal, you can use a basket and drop it a bit lower in the firebox as well.

The calculator indicates your throat should be about 21.71 inches but you indicated yours is a 5x8 oval making it approximately 31.5 sq inches. It is a bit big as is.

Chiminey is recommended at 10.75 inches long from top of the cook chamber for the 4 inch diameter you indicated.

Looks like a solid unit and should be able to get it much more user friendly with a couple of fixes.

Just my 2 cents here...



Blondy_UK
Just Got in trouble for buying tools
Just Got in trouble for buying tools
Posts: 39
Joined: June 15th, 2018, 4:07 am

Re: New reverse flow build

Post by Blondy_UK » September 10th, 2018, 4:24 am

Dirtytires wrote:I’m going to take a stab at this...

I ran the numbers and you are pretty close on firebox size. Your firebox is at 107% and normally I would feel that is fine but on a long horizontal firebox a much greater volume is taken up below the grate. And tho you probably just cooked with it, it also appears much of the space below the grate is full of ash further decreasing the volume. On that type of of a firebox, I might suggest switching to a lump charcoal instead of wood as it tends to burn cleaner and needs less volume (in my experience, at least). I might also experiment with keeping the fire to the far right and away from the cook chamber as much as possible. If you decide to go charcoal, you can use a basket and drop it a bit lower in the firebox as well.

The calculator indicates your throat should be about 21.71 inches but you indicated yours is a 5x8 oval making it approximately 31.5 sq inches. It is a bit big as is.

Chiminey is recommended at 10.75 inches long from top of the cook chamber for the 4 inch diameter you indicated.

Looks like a solid unit and should be able to get it much more user friendly with a couple of fixes.

Just my 2 cents here...
Thanks for the info, i have another couple of tanks so may cut the firebox off and fit another one vertically with a door on the front so i can have a taller fire. What do you think? But before that i will have to get the new one finished.

Sent from my CLT-L09 using Tapatalk




User avatar
Dirtytires
Expert
Expert
Posts: 2183
Joined: November 24th, 2015, 12:36 am
Title: It ain't broke...yet
BBQ Comp Team Name: Dont compete...cook for events once in a while
Location: Phoenix, Az

Re: New reverse flow build

Post by Dirtytires » September 10th, 2018, 9:16 pm

I’ve never liked tanks for fireboxes as they just don’t have the right shape. My feeling is that if you are going to cut it off, build a square one. Trust me, you’ll never go back to a tank.



Blondy_UK
Just Got in trouble for buying tools
Just Got in trouble for buying tools
Posts: 39
Joined: June 15th, 2018, 4:07 am

Re: New reverse flow build

Post by Blondy_UK » September 11th, 2018, 2:38 am

Dirtytires wrote:I’ve never liked tanks for fireboxes as they just don’t have the right shape. My feeling is that if you are going to cut it off, build a square one. Trust me, you’ll never go back to a tank.
My new one is made from 8mm steel plate and is square, i have a sheet of 3mm steel which is the same thickness as a propane tank. What do you think about using 3mm

Sent from my CLT-L09 using Tapatalk




User avatar
Dirtytires
Expert
Expert
Posts: 2183
Joined: November 24th, 2015, 12:36 am
Title: It ain't broke...yet
BBQ Comp Team Name: Dont compete...cook for events once in a while
Location: Phoenix, Az

Re: New reverse flow build

Post by Dirtytires » September 11th, 2018, 9:43 am

Again, just my opinion here but I would use 3 mm (roughly 1/8 inch) to make a square box over a tank every time.

With that said, many would consider it too thin and wouldn’t touch it. Much depends on how hot your fire is, how often you use it, where you store it and how often you clean it. My first smoker was a bolt together from a box made from even thinner material. I used it for almost 10 years and still have it. The key was I never left ash in the firebox and it was never stored unprotected from rain. Take care of it and it will last you a long time.

So, thicker is always better but I would say you are just fine with 3mm.



Blondy_UK
Just Got in trouble for buying tools
Just Got in trouble for buying tools
Posts: 39
Joined: June 15th, 2018, 4:07 am

Re: New reverse flow build

Post by Blondy_UK » September 11th, 2018, 3:00 pm

Dirtytires wrote:Again, just my opinion here but I would use 3 mm (roughly 1/8 inch) to make a square box over a tank every time.

With that said, many would consider it too thin and wouldn’t touch it. Much depends on how hot your fire is, how often you use it, where you store it and how often you clean it. My first smoker was a bolt together from a box made from even thinner material. I used it for almost 10 years and still have it. The key was I never left ash in the firebox and it was never stored unprotected from rain. Take care of it and it will last you a long time.

So, thicker is always better but I would say you are just fine with 3mm.
By looking at the dimensions of the large propane tank what sort of size firebox wood i be looking at including space for an ash pan.

Sent from my CLT-L09 using Tapatalk




Blondy_UK
Just Got in trouble for buying tools
Just Got in trouble for buying tools
Posts: 39
Joined: June 15th, 2018, 4:07 am

Re: New reverse flow build

Post by Blondy_UK » October 13th, 2018, 3:35 pm

Its been a while but i have done some more work on the mk2, not long until i fire it up to set the paint. I used rust-olum 650 degree C paint in silver just to be a bit different but am now thinking it will probably turn a browny colour when used a bit.
Should i do a plain burn first or should i spray inside cc with oil from the start to season? The cc was blasted inside and out before build so should have no nasty's in it.

Sent from my CLT-L09 using Tapatalk




Blondy_UK
Just Got in trouble for buying tools
Just Got in trouble for buying tools
Posts: 39
Joined: June 15th, 2018, 4:07 am

Re: New reverse flow build

Post by Blondy_UK » October 13th, 2018, 3:43 pm

Latest pics, first coat of paint.ImageImageImageImageImageImageImageImageImage

Sent from my CLT-L09 using Tapatalk




Post Reply

Return to “SmokerBuilder® Calculators”