Firebox insulation question?

[fashunsmoke]

I am currently building a new firebox.  I have the old firebox from my pittmaster deluxe which I am standing vertical. It is a 16" diameter tube, and I have inserted another tube of 14" diameter inside of it.  This leaves me with 1" of space between the two that I am filling with some type of insulation.  I was planning on filling the space with concrete.  (weight is not an issue)  My goal is to maximize the efficiency of my firebox by retaining as much heat as possible.  Before I go the concrete mix route, does anyone have any other ideas that I may want to consider for more efficient types of insulation, if so why?

  Also, has anyone insulated with concrete/cement, and was it worth it?

 

[daveomak]

Mornin'........You might try sand for the first go round....If it works....cool........and it shouldn't explode if water gets trapped in it... and it can be replaced easily if needed....

 

[chef jimmyj]

I'm perplexed here...I know a lot of guy's Insulate the Smoke Box to speed recovery...But is it even necessary to Insulate the Firebox of a Charcoal or Stick Burner??? Besides Concrete does NOT like repeated Heating and Cooling...It will be Sand in 2 Seasons...An Air Gap is not a bad Insulator...JJ

 

[fourthwind]

Use kaowool,  Kaowool is also known as ceramic wool.  It comes in 1 inch thick sheets or rolls.   You can also order rock wool in little chunks that you can stuff into the gap if it's easier for you.  You can find this stuff at "Grow Depot"  Both rock and ceramic wools have 2000° ratings.  

Insulating your firebox increases the amount of energy that goes into the cook chamber dramatically.  It also has a couple other side benefits.  It helps preserve the paint on the outside be reducing the surface temp of the outside layer.   This lower temp also increases the safety of working around the pit.  The temp of the outer shell may be under 300° instead of lets say 600° plus   

 

[chef jimmyj]

Learn something new everytime I'm here...Thanks Fourthwind...JJ

 

[fashunsmoke]

Yeah, excellent advice, I read JJ's comment about the cement earlier which put my head in a spin (outside the box) as to what else I could use.  Maybe I should have also added that I am centering the firebox. Although I do not plan on spending a lot of time standing in front of the firebox, I have taken into consideration some of the comments that others on SMF that have stated that heat could be a factor on my legs.  I am kind of collaberating the physics of a vertical smoker into an offset cooking chamber (HPV = Hybrid patio version)I will check into the materials you suggested.  Thanks a bunch.

 

[shorty6 9]

i would highly reccommend some mineral wool, a place that i have bought mine from... http://www.atsacoustics.com/item--Roxul-AFB-Mineral-Wool-2-inch-Case-of-6--1006.html

this stuff is affordable, and very flexable!

 

[hotpit]

i would highly reccommend some mineral wool, a place that i have bought mine from... http://www.atsacoustics.com/item--Roxul-AFB-Mineral-Wool-2-inch-Case-of-6--1006.html

this stuff is affordable, and very flexable!

correct me if I'm wrong here, but that is for a "fire wall" between apartments/condos. and not a hightemp insulation for a fire box???

 

[fourthwind]

correct me if I'm wrong here, but that is for a "fire wall" between apartments/condos. and not a hightemp insulation for a fire box???

It is used for many things, but it works fine for fireboxes.  It is not like fiberglass.  it is made from minerals (aka rocks)  We used to use it, but have now gone to high density ceramic wool which works twice as good in my opinion.  Easier to install and has less problems when welding near it as well.  Only problem for the home builder is that it is harder to find in small quanities.

 

[oldschoolbbq]

Firebrick:

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• oldschoolbbq
• Jul 2, 2012

Got some down the barrel of the Smoke chamber also , I get great recovery and enen temps. once totally heated up,an hour or so...

 

[jerrald]

Is the density ceramic wool placed inside the fire box or line around the outside?

 

[rasimmo]

I found some kaowool sold by the foot online. http://www.piehtoolco.com/contents/en-us/d1356.html

I have not ordered any yet. It does not seem to be a bad price though.

jerrald,

I would line the outside with the blanket type. I think you can get it in block form and use on the inside if that is what you want. 

 

[fourthwind]

The wool type insulaters are sandwiched between metal sheets for best affect. 

 

[jirodriguez]

Even having a second shell will be a huge help - it creates an air break like double pained windows when it's cold outside, but they only feel cool on the inside.