RF insulated cylinder FB with warmer questions

JAK SE MAS · Post by **JAK SE MAS** » September 24th, 2018, 10:16 am

First off I am new to the forum and live in College Station TX and have been cooking 4 comps a year for 7 years and Houston Live Stock Show BBQ Cook off for the past 2. Know down to the question at hand. I am building a 30 X 90 RF (propane tank) with a 30 x 32 FB ( propane tank ) my plans are to insulate the FB by making it squared then putting a 28 x 40 cylinder tank on the fire box for a warmer. My question is should I put the warmer directly on top of fire box and insulate up to it or should i insulate the complete FB and have a pipe with damper run through the top into FB. I kind of planed to put the damper in ether way. Last question is should I insulate the door of FB and the back of the of the FB or will I be fine just top bottom and sides. I am on a budget so most of these things were free or cheep. Any help would be appreciated

bstory · Post by **bstory** » September 24th, 2018, 3:47 pm

The entire FB except the bottom plate should be insulated. Put the cylinder on top of the FB with a 4” piece of round pipe with a slide plate to control how much heat will go into the warmer.

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ajfoxy · Post by **ajfoxy** » September 24th, 2018, 4:35 pm

Post by **Big T** » September 24th, 2018, 4:38 pm

JAK SE MAS · Post by **JAK SE MAS** » September 24th, 2018, 7:01 pm

That is kind of what I was thinking but my FB is a cylinder. I was planning on making a square box around the cylinder so in that case would you still leave the bottom uninsulated?

AndrewPalmer71 · Post by **AndrewPalmer71** » September 24th, 2018, 7:38 pm

I can envision how you'd frame out a cylinder in that manner. Either way, after you frame it, stuff the voids/ open areas with insulation like Bstory mentioned.

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Dirtytires · Post by **Dirtytires** » September 25th, 2018, 12:33 am

You can insulate all sides without a problem. I did all 6 sides of mine included a double walled/insulated door.

Just something to consider... your tank is most likely fairly thin and can be the weak point in a smoker. The heat cycles and ash abuse the firebox a bunch. Many take this into consideration and plan to cut off and replace the firebox when it burns thru. I mention this just so you are aware and can make an educated decision on replacing the firebox vs buying heavier steel now. It’s a tough call but given the choice, I would probably go heavier steel with my budget and not insulate. Your materials seem to be free-bees tho so I see your current direction has positive points as well.

Either way is going to work out just fine...

Post by **Pete Mazz** » September 25th, 2018, 3:54 am

JAK SE MAS · Post by **JAK SE MAS** » September 25th, 2018, 6:36 am

Dirtytires wrote:You can insulate all sides without a problem. I did all 6 sides of mine included a double walled/insulated door.

Just something to consider... your tank is most likely fairly thin and can be the weak point in a smoker. The heat cycles and ash abuse the firebox a bunch. Many take this into consideration and plan to cut off and replace the firebox when it burns thru. I mention this just so you are aware and can make an educated decision on replacing the firebox vs buying heavier steel now. It’s a tough call but given the choice, I would probably go heavier steel with my budget and not insulate. Your materials seem to be free-bees tho so I see your current direction has positive points as well.

Either way is going to work out just fine...

The FB is a (propane tank) 1/4 inch thick and everything I have read said this was the go to thickness.

AndrewPalmer71 · Post by **AndrewPalmer71** » September 25th, 2018, 6:48 am

Yep. You're right. Just double check that your cylinder is within specs for fb size before boxing it in. It would be a lot of work to correct any issues with fb size.

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Dirtytires · Post by **Dirtytires** » September 25th, 2018, 10:40 am

0.25 inch is great. Propane tanks I’ve worked with in the past have been considerably thinner.

bstory · Post by **bstory** » September 25th, 2018, 4:37 pm

Just my opinion, but I would consider making the entire firebox out of plate and make it all square and the place your cylinder on top for the warmer. So if you are doing insulated, build a square firebox to the specs needed and then an outer box to hold the insulation and inner box. The round FB is a pain in the butt!!!! I promise from loading wood to dumping ash during a long cook. They work obviously because you see them everywhere, if you are going to buy plate to put around the cylinder I would just buy enough to make the entire FB square. My first two smokers I built, I made round fire boxes using part of the tank and they just suck. I will never make anything other than a square firebox again. And you will not be disappointed with an insulated firebox, man it’s awesome.

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JAK SE MAS · Post by **JAK SE MAS** » September 25th, 2018, 6:50 pm

bstory wrote:Just my opinion, but I would consider making the entire firebox out of plate and make it all square and the place your cylinder on top for the warmer. So if you are doing insulated, build a square firebox to the specs needed and then an outer box to hold the insulation and inner box. The round FB is a pain in the butt!!!! I promise from loading wood to dumping ash during a long cook. They work obviously because you see them everywhere, if you are going to buy plate to put around the cylinder I would just buy enough to make the entire FB square. My first two smokers I built, I made round fire boxes using part of the tank and they just suck. I will never make anything other than a square firebox again. And you will not be disappointed with an insulated firebox, man it’s awesome.

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It’s called funds and I’m limited. I already need 1 sheet of 1/4 for the plate in the pit for the RF plate at a price of 225 dollars a 4x8 sheet, if I make a square FB that would be another 225$. I can spend less than that with the cylinder and can insulate and still have a little left over of the 225. I have a cylinder on my small pit and it is a little pain but not to bad, but I get where you’re coming from.

Post by **Big T** » September 25th, 2018, 7:46 pm

I know where you're coming from. All of my personal builds have been built from scrap piles and leftover materials from other projects. You can make the round FB work, just think about the layout before you start building and you can get the ash pan and fire basket fit in there fairly well.

bstory · Post by **bstory** » October 1st, 2018, 2:49 pm

JAK SE MAS wrote:
bstory wrote:Just my opinion, but I would consider making the entire firebox out of plate and make it all square and the place your cylinder on top for the warmer. So if you are doing insulated, build a square firebox to the specs needed and then an outer box to hold the insulation and inner box. The round FB is a pain in the butt!!!! I promise from loading wood to dumping ash during a long cook. They work obviously because you see them everywhere, if you are going to buy plate to put around the cylinder I would just buy enough to make the entire FB square. My first two smokers I built, I made round fire boxes using part of the tank and they just suck. I will never make anything other than a square firebox again. And you will not be disappointed with an insulated firebox, man it’s awesome.

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It’s called funds and I’m limited. I already need 1 sheet of 1/4 for the plate in the pit for the RF plate at a price of 225 dollars a 4x8 sheet, if I make a square FB that would be another 225$. I can spend less than that with the cylinder and can insulate and still have a little left over of the 225. I have a cylinder on my small pit and it is a little pain but not to bad, but I get where you’re coming from.

I understand. I have a plan.
Put your cylinder with an opening for a door but no door ( but do actually have a door on the cylinder) in your box and then stuff in you insulation and and weld some plate from the edge of the cylinder door opening to the wall of the outer (square) firebox, closing off all the space between the cylinder and the square box that has the insulation. Then make a double plated insulated square firebox door and completely bypass having a rounded door to the cylinder.

I hope that makes sense, and that may have been your plan anyway. I will attach a pic of my door. It’s two pieces of 1/4 plate. 2x2”angle and 1.5” insulation

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JAK SE MAS · Post by **JAK SE MAS** » October 1st, 2018, 3:12 pm

That's what I was thinking.

Post by **Rodcrafter** » October 23rd, 2018, 6:03 pm

Nice work

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