web analytics
Question about insulation - Forno Bravo Forum: The Wood-Fired Oven Community

Announcement

Collapse

Photo Galleries are back! Instructions below.

Dear forum users,
Thank you for your patience with the Photo galleries. We've got your galleries online!
We have finished writing a custom script to migrate the PhotoPlog to vBulletin5’s albums.

Unfortunately V-Bulletin killed the "Photoplogs" in their software upgrade which was unforeseen and we're the first development group to have written a script for getting the galleries back... that said, it took some time to reverse engineer the code and get the albums to move over seamlessly!

Forum users will be able to access their “PhotoPlog” images through their user profile page by clicking on the “Media” tab.
They will also be able to browse other albums by going to the albums page. (On the forum site, there is a link in the black bar beside “Forums” to the albums.)

In order for users to create an album please follow the steps below.
1) Go to user profile page and click “Media”
2) Click Add Photos
3) Enter Photo Gallery Title in the first field
4) Click Upload or Select from Photo Album to add photos
5) Click Post
6) Once posted, the album will be created as a “Topic” on the albums page for the public to see. The topic title will be the “Photo Gallery Title” they created before uploading their photos.


To create this migration path we used vBulletin5’s default album structure. Unfortunately, it won’t work like the “PhotoPlog” but is an album/gallery component on the forum now.
See more
See less

Question about insulation

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • Question about insulation

    Hi all,

    I'm looking at a castable insulation to go under my hearth and wondering if anyone can tell me if my maths is in the ballpark. The insulation that I am looking at has a K value of 0.18 at 500C, and I understand that R = 1/K, so the R value per inch = 1/0.18 = 5.5.

    The FB plans call for 4 inches of vermiculite concrete mixture. Google seems to be telling me that loose vermiculite has an R value of around 2.1, and I assume it would be slightly lower with the cement mixed in - call it 2? So 4 inches of vermcrete has an R of around 8.

    So is my thinking right that 2 inches of this castable insulation will be more effective than 4 inches of vermcrete?

    I'm very open to the idea that I don't know what I'm talking about here
    My oven: http://www.fornobravo.com/forum/21/t...html#post46599
    My blog: Live For Pizza

  • #2
    Re: Question about insulation

    I'm no expert on this, but I'll jump in. In general, members of this board (myself included) have had good luck with 2 inches of insulation board instead of the 4-inch vermiculite concrete layer. I think James said that 2 inches of the board that FornoBravo sells is a slightly better insulator than 4" of vermi-concrete. The more insulation the better, of course.

    Several months ago, I compared the thermal conductivity values for several different types of boards that people were using, and they ranged from about 0.69 to 1.3 (in BTU in/hr deg.F sq ft) at 540 deg.C (1200 F). The products included Insblok-19, SuperIsol, FB Board, Marinite, and Kaowool board (Note: Kaowool loses strength when wet).

    As a concrete example of conductivity, I was told that with a constant heat of 1100 degrees F on one side of Insblok-19 (with a thermal conductivity of 0.84 at 1000 degrees F), the other side will be about 200 degrees F.

    I hope that helps!
    Last edited by dbhansen; 10-02-2008, 01:42 PM.
    Picasa web album
    Oven-building thread

    Comment


    • #3
      Re: Question about insulation

      Sure does!
      So the thermal conductivity value you are talking about looks like it's in english units? If so, english units = 1.73K. That puts the castable I'm looking at (Moral Coolcast) 0.27 EU and the board (V-Lite 100 AL) 0.20. That seems like it's a lot lower than the range you mentioned - have I found a really good product, or just made a mistake in my maths somewhere?
      My oven: http://www.fornobravo.com/forum/21/t...html#post46599
      My blog: Live For Pizza

      Comment


      • #4
        Re: Question about insulation

        Yes, English units. Sorry, I don't know the conversion, but here is a website that converts thermal conductivity numbers.

        I think most people building wood-fired ovens (at least in the U.S.) stay away from the castable insulating materials and use vermiculite or perlite + concrete instead, probably due to cost and availability. Some have said that castables are "fussy" to work with, and it can be difficult to get the mixture right. Using vermiculite is a "tried and true" method for these ovens, and usually inexpensive.

        When looking at insulating board, be sure to check on the other properties besides conductivity, such as density, compressive strength, resistance to water damage, and shrinkage.
        Picasa web album
        Oven-building thread

        Comment

        Working...
        X