Go Back   Forno Bravo Forum: The Wood-Fired Oven Community > Pizza Oven Design and Installation > Getting Started

Like Tree4Likes

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 08-22-2005, 02:03 PM
james's Avatar
Brick Oven Merchant
 
Join Date: Mar 2005
Location: Pebble Beach, CA
Posts: 4,648
Default Insulation Efficiency

I know that some folks are talking about getting the insulation right to keep heat inside the oven, and wood consumption down. This is true for both site built and FB precast ovens.

We recommend a 1" Insulfrax insulating blanket (6#) and 4"-6" vermiculite or perlite as a general rule. Here are some simulated insulation numbers we had an engineer do a while back.

James

*******************

I had an insulation engineer run a test, and conclude that the blanket replaces 2" of loose vermiculite. We had them run a simulation where they added 1" of insulfrax, and reduced 1" of vermiculite. 1":4", 2":3", etc. over a 24 hour 1000F exposure. The outer face tested consistently dropped by adding 1" more insulfrax and 1" less vermiculite.



1" Insulfrax Blanket 6#, 4" Vermiculite 1000F** 172F

2" Insulfrax Blanket 6#, 3" Vermiculite 1000F** 161F

3" Insulfrax Blanket 6#, 2" Vermiculite 1000F** 151F

4" Insulfrax Blanket 6#, 1" Vermiculite 1000F** 142F

5" Insulfrax Blanket 6# ******* 1000F** 135F



Thinking about it, I should ask him to add 1# insulfrax, and drop 3" of vermiculite and re-run the test. I would note that after 24 hours of 1000F, (which you will not approach), the outer face is barely warm.
__________________

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.

Last edited by james; 06-27-2006 at 03:17 PM.
Reply With Quote
  #2  
Old 08-22-2005, 03:19 PM
paulages's Avatar
Journeyman
 
Join Date: May 2005
Location: portland, or
Posts: 292
Default

james,
ask him if it is possible to compare these figures to castable refractory insulation (in place of either the refrax blanket OR the vermiculite insulation. i would think the castable might perform similar to the blankets.

the closest figures i can contribute are:

roughly 1.5-2 inches of 2500deg F rated castable insulation reaches 120-140 deg.F when the interior is 700-950 for 2 -3 hours. (i know those are a lot of variables, but it at least gives us a ballpark idea of how well it functions).
__________________
-paul
overdo it or don't do it at all!

Last edited by paulages; 08-22-2005 at 03:22 PM.
Reply With Quote
  #3  
Old 08-22-2005, 03:30 PM
james's Avatar
Brick Oven Merchant
 
Join Date: Mar 2005
Location: Pebble Beach, CA
Posts: 4,648
Default

I'll see if I can do that and get back.

The figures above are aftter 24 hours -- which is a more extreme test, so the insulation is more efficient at those thicknesses. Paul, are you going to add loose vermiculite around the dome still?

James
__________________

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
  #4  
Old 08-22-2005, 04:07 PM
paulages's Avatar
Journeyman
 
Join Date: May 2005
Location: portland, or
Posts: 292
Default

yes---whenever i get around to finishing the walls. i have a million projects going on right now...but i've found plenty of time to cook in it!
__________________
-paul
overdo it or don't do it at all!
Reply With Quote
  #5  
Old 08-07-2007, 09:12 PM
Versachi's Avatar
Laborer
 
Join Date: Sep 2006
Location: Thunder Bay Ontario, Canada
Posts: 73
Question Re: Insulation Efficiency

Just wondering if anyone has used fiberglass insulation around their dome? I wouldn't use it directly on the dome but if you had a layer of insulating blanket couldn't you use batts around your dome. The r-value would be much higher than perlite or vermiculite. I don't think temperature would be much of an issue since fiberglass is made at a higher temperature than we could fire the oven
__________________
"Opportunity is missed by most people because it is dressed in overalls and looks like work." Thomas A. Edison
Reply With Quote
  #6  
Old 08-08-2007, 03:43 AM
Journeyman
 
Join Date: Apr 2005
Location: Brazil
Posts: 306
Default Re: Insulation Efficiency

Versachi:

Yes, you could use fiberglass to isolation your dome.
Depending on cloth type, the blanket has different temperature capability. As lower as 150°C to higher 500°C.
You could use an inch of vermiculite/cement mixture and cover it with fiberglass blanket.
Search by Pizzabrasil and see oven pictures and better explanations about this matter.

Good luck

Luis
Reply With Quote
  #7  
Old 08-08-2007, 03:56 AM
dmun's Avatar
Moderator
 
Join Date: Jul 2005
Location: New Jersey USA
Posts: 4,216
Default Re: Insulation Efficiency

If you use domestic fibreglass batts, be sure to strip off the paper vapor barrier, which is combustible.
Reply With Quote
  #8  
Old 09-18-2007, 03:11 PM
RCLake's Avatar
Journeyman
 
Join Date: Jul 2007
Location: Corsicana,Texas
Posts: 433
Default Re: Insulation Efficiency

I'm shopping for this in Dallas and I'm getting quotes on the blanket for 1" and 2" but also for 8 pound and 6 pound. I'm assuming the heavier is better but does anyone know by how much (i.e. 8/6 better
Reply With Quote
  #9  
Old 03-17-2008, 07:23 AM
Laborer
 
Join Date: Dec 2007
Location: Vermont
Posts: 57
Default Re: Insulation Efficiency

Since this thread was dredged up, I'll ask a question.

I have been taking in all the insulation conversations & I'm wondering about the FB blankets. I haven't actually seen it so I'm wondering how compressible it is, seeing how people are adding a hardcoat of vermiculite concrete/stucco to their oven over the blanket.

Wouldn't heavy-weight coating like that tend to compress the blanket, reducing it's efficiency?
mrchipster likes this.
Reply With Quote
  #10  
Old 03-17-2008, 09:13 AM
CanuckJim's Avatar
Il Pizzaiolo
 
Join Date: Jan 2006
Location: Prince Albert, Ontario, Canada
Posts: 1,480
Default Re: Insulation Efficiency

TD, et al,

The vermic/cement mixture is quite light, really, so the blanket(s) don't compress significantly. I'd recommend 8 lb over 6 anytime.

Jim
__________________
"Made are tools, and born are hands"--William Blake, 1757-1827
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



All times are GMT -7. The time now is 10:27 PM.

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