Insulating a round offset firebox.

[BayoustateBBQ]

Has anyone here insulated their round firebox? Do you have to use oven brick? Any cheaper methods? when you have a majority of your heat radiating out of the fire box, surely insulating it would help control temps and cut down on fuel right?

[luke duke]

Use mineral wool

[captndan]

I used the stuff NASA used on the space shuttle. Got it at a fireplace and stove store.

[Texas Turtle]

I assume that you could put fire brick inside the firebox (I've been looking for some around here), but where do you put the mineral wool?

[BayoustateBBQ]

Found mineral wool and I also found some ceramic wool that was like $25 for a 12" x 2ft length. I'm taking it you mount any wool type material around the outside of the firebox?

[BayoustateBBQ]

I would estimate I'm losing atleast 50% of my heat through the outside of the firebox

[pbj]

The use of mineral wool should include covering the mineral wool so fibers, etc. don't get sucked into the fire box and through the cooking chamber. I've worked with it professionally and it gets everywhere. Wear a mask when working with it.
Curly

[Mark]

Here is a much better alternative to outside insulation: An inside heat shield.

Basically, it's a stainless steel sheet metal lining that is seperated from the firebox via spacer rods.

You will probably need 2 pieces of stainless steel sheet metal each a little more than half the length of the fire box and each a little longer than the circumference.

First you need to weld or bolt (or whatever) several horizontal spacer rods running the inside length of the firebox. I'd say 4 to 6 rods in total.

Then you simply roll up each piece of stainless steel sheet metal, insert it and let it go. When it atempts to spring back flat, it should fit snugly against the spacer rods creating a dead air space between the stainless steel sheet metal and the fire box.

Then do the same for the other piece. And by making each peice a little more than half the length of the firebox, they should overlap slightly in the middle, thereby creating a complete heat shield.

Of course, the ends will not be shielded, but then they're not as critical a source of heat loss.

Comnprehende? If not, drop me a PM.

Mark

[BayoustateBBQ]

Ok so you are saying to put the wool in the firebox? I was under the impression you wrap the outside

[Mark]

No. Forget about "wool." The attached picture is for an old Bandera but the concept is the same.

Does this help?

[ButtBurner]

Originally Posted by Mark

No. Forget about "wool." The attached picture is for an old Bandera but the concept is the same.

Does this help?

Im going to do something similar but with 1/4" plate

[BayoustateBBQ]

Ok, got the dead air space insulation idea. I have some 18guage sheet metal and a sheet metal slip roll so I can roll the metal to the same radius as the fire box. Theres spots on my fire box that have litteraly cooked the powder coat on the outside so I have to do something. Would you suggest some 1 1/4 fire bricks on the bottom aswell? Found some on ebay for a good price,however are they fairly easy to cut without cracking them?

[Mark]

No. I suggest an inner heat shield of sheet metal; stainless steel if possible as it should never need replacing. It should also be seperated from the wall of the fire box somehow; like spacer rods.

[Mark]

PS: If your placie the heat shield on the inside, you'll probably be better off NOT rolling it. That's because you want it to "snap" back into it's original flat form.

[Mark]

PSS: I mean try and snap back. But it can't because it is contained by the roundness of the fire box and that force alone should be sufficient to keep it pressed tightly enough against the firebox (seperated by spacer rods).