Reverse Flow Cabinet Build Questions

[FishinMusician]

Hi guys,
Running the idea of a reverse-flow cabinet smoker build in my head and had a few questions that I haven't been able to find through the search function.

A little info before the questions:

-Small/Medium size: Haven't gotten as far as exact dimensions yet, but thinking on the small/medium size of things is where I plan to go. For example, maybe somewhere between the Humphrey's Weekender and Long Weekenders, or LSG Minis (+ a little maybe), or Pit Maker's Safe.I apologize if this is too vague.

-Material: 1/4 Metal

Questions
-Insulation: Being as the smoker will be used in South Texas, and low 30s is about as low as we go outside of extreme circumstances, and not for long, is a fully insulated smoker necessary?

-Insulation 2: Do I need to insulate between the fire box and chamber? Thicker metal etc..?

-Chamber inlet: :Knowing throat is important, that will be calculated, but what are the best options for smoke inlet into the chamber? Have noticed some smokers where the inside chamber walls on sides and back leave about a 1" gap at the top for the smoke/heat to enter.

-Basket size/charcoal amount: With the ballpark size I'm looking at (as mentioned earlier), what size charcoal basket would you recommend? Also, I'm thinking 20lbs + of coals should be sufficient? I'm used to working the round basket on my Weber Smoky Mountain (22") that I've modified to comfortable hold up to 20+lbs w/wood chunks.

-Fire Box Intake: Would a single 2" ball valve be sufficient for in-flow?

Would appreciate any help that I could get.

I really enjoy cooking on my Weber Smoky Mountain 22, but two of the bigger cooks I've done have made my mind and eyes wonder a bit. I feel with the bigger cooks, I can get a better product + less hassle if I upgrade size and functionality (door vs. lid + grate stack),

Thanks.

 

[onemanlan]

Hi guys,
Running the idea of a reverse-flow cabinet smoker build in my head and had a few questions that I haven't been able to find through the search function.

A little info before the questions:

-Small/Medium size: Haven't gotten as far as exact dimensions yet, but thinking on the small/medium size of things is where I plan to go. For example, maybe somewhere between the Humphrey's Weekender and Long Weekenders, or LSG Minis (+ a little maybe), or Pit Maker's Safe.I apologize if this is too vague.

-Material: 1/4 Metal

Questions
-Insulation: Being as the smoker will be used in South Texas, and low 30s is about as low as we go outside of extreme circumstances, and not for long, is a fully insulated smoker necessary?

-Insulation 2: Do I need to insulate between the fire box and chamber? Thicker metal etc..?

-Chamber inlet: :Knowing throat is important, that will be calculated, but what are the best options for smoke inlet into the chamber? Have noticed some smokers where the inside chamber walls on sides and back leave about a 1" gap at the top for the smoke/heat to enter.

-Basket size/charcoal amount: With the ballpark size I'm looking at (as mentioned earlier), what size charcoal basket would you recommend? Also, I'm thinking 20lbs + of coals should be sufficient? I'm used to working the round basket on my Weber Smoky Mountain (22") that I've modified to comfortable hold up to 20+lbs w/wood chunks.

-Fire Box Intake: Would a single 2" ball valve be sufficient for in-flow?

Would appreciate any help that I could get.

I really enjoy cooking on my Weber Smoky Mountain 22, but two of the bigger cooks I've done have made my mind and eyes wonder a bit. I feel with the bigger cooks, I can get a better product + less hassle if I upgrade size and functionality (door vs. lid + grate stack),

Thanks.

Well, I have a Humphrey's BB so if you want those dimension let me know.

My answers are based on what I observe on the BB.

Insulation 1: I'm in Alabama, haven't been through a winter with it yet, but given what I've this one has more than enough insulation to cook through it without too much loss in efficiency. Even with the thickness of the BB I can still feel heat through the walls in places. You probably don't need to go full Humphrey's thickness, but you're giving up efficiency.

Recall insulation works in both in both directions - keeping outside heat(or cold out) & keeping inside heat(or cold) in.

Insulation 2: A plate separates the firebox from the cook chamber. A water pan goes above that as well.

Basket: The BB can hold about 15-18 lbs or so of charcoal. 75% full charcoal box has netted me a 14-15 hour cook(which is ~1 lb/hr). I can measure it if you like.

Intake: Yeah, 2 inch ball valve is more than enough. When you're at cooking temps the inlet valve can be closed to leave 1/4 or 1/8th of an opening while mainlining temp.

I hope that helps a bit. I'm excited for your project! Sounds fun. Wish I had the fab skills to help more.

 

[boogiechillen]

I’d say no insulation between firebox and cooking chamber. Maybe just thicker steel there.

Mine has about a 1” gap around the three sides at the top for the smoke to enter the cook chamber.

2” ball will be plenty. Mine is 1.5”.

I’d assume you would make the charcoal basket biggest enough to slide in and out of the chamber. 20 lbs should be plenty.

 

[FishinMusician]

Well, I have a Humphrey's BB so if you want those dimension let me know.

My answers are based on what I observe on the BB.

Insulation 1: I'm in Alabama, haven't been through a winter with it yet, but given what I've this one has more than enough insulation to cook through it without too much loss in efficiency. Even with the thickness of the BB I can still feel heat through the walls in places. You probably don't need to go full Humphrey's thickness, but you're giving up efficiency.

Recall insulation works in both in both directions - keeping outside heat(or cold out) & keeping inside heat(or cold) in.

Insulation 2: A plate separates the firebox from the cook chamber. A water pan goes above that as well.

Basket: The BB can hold about 15-18 lbs or so of charcoal. 75% full charcoal box has netted me a 14-15 hour cook(which is ~1 lb/hr). I can measure it if you like.

Intake: Yeah, 2 inch ball valve is more than enough. When you're at cooking temps the inlet valve can be closed to leave 1/4 or 1/8th of an opening while mainlining temp.

I hope that helps a bit. I'm excited for your project! Sounds fun. Wish I had the fab skills to help more.

I’d say no insulation between firebox and cooking chamber. Maybe just thicker steel there.

Mine has about a 1” gap around the three sides at the top for the smoke to enter the cook chamber.

2” ball will be plenty. Mine is 1.5”.

I’d assume you would make the charcoal basket biggest enough to slide in and out of the chamber. 20 lbs should be plenty.

Appreciate your replies, guys.

onemanlan: if you wouldn't mind with the measurements, that'd be fantastic. I don't know anyone around here who has one so I can't really go measure one in person, and not sure if any of the shops would want to help me out (and understand).

As for my fab skills, I have a few, but luckily my wife's cousin is a welder by trade, and he volunteered his time. Lucky lucky

 

[FishinMusician]

Thanks for the replies, guys!

onemanlan: I'd really appreciate the measurements of your basket, and fire box if you wouldn't mind. Whenever you get time, trust me I'm in no hurry here. I don't know anyone with anything similar, so I can't measure myself.

As for my fab skills, I have some moderate ones, but am very lucky that my wife's cousin, who is a welder by trade, volunteered his time when I mentioned wanting this style of pit.

 

[onemanlan]

Do my best to report back in a day or so.

 

[onemanlan]

Here you go - I pulled the top 2 values from Humphrey's Website. All values in inches.

Outside Dimensions: 24w x 29d x 43h

Cooking chamber: 15.25w x 22.5d x 18h

Firebox Chamber Size(inside): 14w x 17.5d x 5h

Firebox size: ~15.5w x 23d x ~14h

The Firebox is kinda hard to measure inside b/c of the edges of the doorway make it difficult to measure side to side.

 

[FishinMusician]

Here you go - I pulled the top 2 values from Humphrey's Website. All values in inches.

Outside Dimensions: 24w x 29d x 43h

Cooking chamber: 15.25w x 22.5d x 18h

Firebox Chamber Size(inside): 14w x 17.5d x 5h

Firebox size: ~15.5w x 23d x ~14h

The Firebox is kinda hard to measure inside b/c of the edges of the doorway make it difficult to measure side to side.

You are the man sir. Was able to find the top two myself as well, but the firebox was the one I needed and I really appreciate it!

Kinda rough drafting some things right now. Thinking a 1” insulated wall should do. May post some of the CAD work later.

Thanks again

 

[FishinMusician]

Guess a couple of more questions:

-What's the heat/smoke entry like from the fire box into the side walls and back wall? I have an idea (similar to the entry into the chamber from the side walls and back wall is what I'm thinking).

-I have access to a lot of good "scrap" 20 guage stainless steel, and was wondering if two sheets of that with insulation sandwiched in between would suffice for the outside walls and doors (+ the framing, obviously)? To me it seems like it'd work find, but I'm not a pro at this. Just seems like a big opportunity to save a little cash, and also keep it lighter.

 

[onemanlan]

I'm not sure if this helps answer question 1. It's a video review I made a while back with some close up pics.

No clue on question #2. Not an expert in that regard either.