Go Back   Forno Bravo Forum: The Wood-Fired Oven Community > Pizza Oven Design and Installation > Tools, Tips and Techniques

Like Tree1Likes

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 09-24-2009, 12:31 AM
kebwi's Avatar
Il Pizzaiolo
 
Join Date: Aug 2009
Location: Seattle, WA, USA
Posts: 1,010
Default Why not insulating firebricks for hearth insulation?

I've never seen any suggestion of using insulating firebricks for the hearth insulation, only various "boards" (superisol) and aerated concretes (vermiculite & perlite). Perhaps I'm misunderstanding something, but isn't this exactly what insulating firebricks are designed for?

What am I missing here? Are they really expensive or not very insulative or difficult to work with? I'm sure there's a perfectly good reason for why they aren't recommended, much less barely discussed, but I'm not aware of what that reason is yet.

Final thought: even if they shouldn't be used for the entire floor, would they make good standoffs or "columns" embedded into the vermcrete/perlcrete at, say 12"-18" spacing (half bricks perhaps) to provide compression resistance to the weaker concrete?

...of course that idea is only necessary if compression is a serious issue in the first place and I get a very strong impression from this forum that compression is virtually never a problem, even at 7:1, but would they help in such a case?

Just brainstorming.

Thanks.
__________________

Website:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

WFO Webpage:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Thread:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Reply With Quote
  #2  
Old 09-24-2009, 01:25 AM
david s's Avatar
Il Pizzaiolo
 
Join Date: Mar 2007
Location: Townsville, Nth Queensland,Australia
Posts: 4,726
Default Re: Why not insulating firebricks for hearth insulation?

I agree with you. Why not use them ? Trouble is they're expensive. They are also designed to withstand really high temps (1200 C+), which in our application we don't need. Aerated concrete (Hebel) is another alternative, but it is also dearer than vermiculite, for me anyway. If you can access insulating firebricks at a good price then go for it.
Reply With Quote
  #3  
Old 09-24-2009, 01:29 AM
david s's Avatar
Il Pizzaiolo
 
Join Date: Mar 2007
Location: Townsville, Nth Queensland,Australia
Posts: 4,726
Default Re: Why not insulating firebricks for hearth insulation?

Kebwi,
Forgot to add that insulating firebricks are not that strong because of all that air in them. Probably not much stronger, if at all, than vermiculite. There's a job for you, run some tests.
Reply With Quote
  #4  
Old 09-24-2009, 04:14 AM
John K's Avatar
Apprentice
 
Join Date: Sep 2009
Location: Australia
Posts: 216
Default Re: Why not insulating firebricks for hearth insulation?

Hi Guys

I am in the process of laying Insulation bricks on my hearth and will cost me just under $250.00 (75 Bricks).

The supplier advised that I will get better insulation properties using these and I won't have an issue of these crumbling under the weight of the dome.


I guess I will know shortly!!
Reply With Quote
  #5  
Old 09-24-2009, 04:41 AM
Il Pizzaiolo
 
Join Date: Mar 2009
Location: USA
Posts: 1,436
Default Re: Why not insulating firebricks for hearth insulation?

Hi John K

Are these the very white bricks they use in kilns and furnaces ? I want to build an outdoor furnace and Im thinking about using a product like that.
Thanks
Mark
Reply With Quote
  #6  
Old 09-24-2009, 05:07 AM
John K's Avatar
Apprentice
 
Join Date: Sep 2009
Location: Australia
Posts: 216
Default Re: Why not insulating firebricks for hearth insulation?

Hi Mark

Yes these are the white bricks and are very light!! see attached photo

I also jumped on the suppliers website and have found this spill listed under Insulation Bricks


INSULATION BRICK

Field Furnace Refractories is an agent for ISOLITE Insulating Firebrick.
The Insulating Firebricks have densities ranging from 0.50 -1.8 grams per cubic centimetre and temperature ratings from 900oC to 1800oC.

Isolite Insulating Firebricks have low thermal conductivity good cold crushing strength; low reheat shrinkage and excellent dimensional tolerances.

We can supply the insulating firebrick required for any furnace design to give optimum thermal insulation. Isolite IFBs are used as back up and as a hot face in a myriad of furnaces and kilns.

hope it helps

John


You can follow my build at http://www.fornobravo.com/forum/f8/j...-wfo-7911.html (John's 42inch Aussie WFO)
Attached Thumbnails
Why not insulating firebricks for hearth insulation?-dsc03883.jpg  

Last edited by John K; 09-24-2009 at 05:09 AM.
Reply With Quote
  #7  
Old 09-24-2009, 05:07 AM
david s's Avatar
Il Pizzaiolo
 
Join Date: Mar 2007
Location: Townsville, Nth Queensland,Australia
Posts: 4,726
Default Re: Why not insulating firebricks for hearth insulation?

Yes they are very white and very light, also very refractory.
Reply With Quote
  #8  
Old 09-24-2009, 05:18 AM
dmun's Avatar
Moderator
 
Join Date: Jul 2005
Location: New Jersey USA
Posts: 4,216
Default Re: Why not insulating firebricks for hearth insulation?

They work fine: they have the same insulation value as vermiculite concrete. The problem is price. At least around here they are far more expensive than regular firebrick, and an order of magnitude more than vermiculite concrete. If you're spending that kind of money, you should spring for the modern insulation boards, and get the advantage of higher insulation values.

And just for the record: there's no compressive strength problem with vermiculite concrete. It has no tensile strength, but you'd be hard pressed to crush it.
__________________
My geodesic oven project:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
,
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Reply With Quote
  #9  
Old 09-25-2009, 04:43 AM
Il Pizzaiolo
 
Join Date: Mar 2009
Location: USA
Posts: 1,436
Default Re: Why not insulating firebricks for hearth insulation?

I think I will stick with the vermicrete,, I love to work with things that have a known factor,,, I have used it with good success, and to date it amazes me how much heat it can hold...

Mark
Reply With Quote
  #10  
Old 09-29-2009, 09:37 AM
kebwi's Avatar
Il Pizzaiolo
 
Join Date: Aug 2009
Location: Seattle, WA, USA
Posts: 1,010
Default Re: Why not insulating firebricks for hearth insulation?

So, let's say, theoretically ;-) that I have access to 50 new insulating firebricks for $75. Nudge, nudge, wink, wink. Clearly, that's a good price. It won't really complete the floor, even for a 36" oven. Could I make a workable design with this by filling the center with bricks and then expanding the circumference with perlcrete, or vs/va, or something like that?

I'm thinking this might work...but just to clarify, as was stated above in this thread, it is only as insulating as perlcrete, not as insulating as board, so I either need a few inches worth, or I need a layer of perlcrete above or below it...or some board...I'm thinking of putting 1" to 2" Insblock 19 under the hearth anyway, regardless of whether I use perlcrete or insulating firebricks.

Thoughts?

Thanks, as always.
__________________

Website:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

WFO Webpage:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Thread:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


Last edited by kebwi; 09-29-2009 at 09:41 AM.
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Igloo style dome insulation Throw Deep Pompeii Oven Construction 19 12-18-2009 02:40 PM
Blanket Insulation altamont Pompeii Oven Construction 12 10-01-2009 08:09 AM
Finding firebricks and insulation in Switzerland Frances Getting Started 0 09-14-2007 08:12 AM
Super Isol vs insulating firebricks readie Getting Started 2 06-15-2007 10:25 AM
How they make insulating firebricks james Getting Started 4 10-09-2006 09:51 AM


All times are GMT -7. The time now is 05:28 PM.

Powered by vBulletin® Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.6.0
2006/10 Forno Bravo, LLC