web analytics
Thermalite aerocrete blocks for hearth 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

Thermalite aerocrete blocks for hearth insulation?

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

  • Thermalite aerocrete blocks for hearth insulation?

    I know the conventional wisdom is to use perlite/vermiculite concrete or insulating board under the hearth, but I came across these Thermalite aerocrete blocks in the shop the other day: http://www.hanson.co.uk/67/blocks/th...cts/turbo.html
    I should probably say straight away that I've got no affiliation with this company!
    They're made from waste pulverised fuel ash, and have a thermal conductivity of 0.11 W (m.K), compared with 0.094 W (m.K) for vermiculite concrete (taken from this website http://www.william-sinclair.co.uk/in...retes?OpenPage. It seems pretty close to vermiculite concrete in insulating ability, and it'll be very easy to lay these. They're cheap too - about 65p a block (~440x210x100).

    I took my blowtorch to one earlier and was able to heat a spot up to bright yellow after 10 minutes...

    ... and could comfortably keep my thumb about 4cm away from the heated spot once I turned the blow torch off...

    The discoloration was only about 1-2mm deep - obviously the blocks wouldn't get this sort of direct heat unless my build goes badly wrong There's some more pictures on my blog if anyone's interested.

    I'm thinking about using these for my hearth insulation as they'll be so convenient and cheap. I know that there's been some discussion about using AAC blocks, but are these different? They're made of 80% ash, and I know ash is a traditional insulator for ovens. I'd be interested in hearing what people think.
    http://fornoeconomico.blogspot.com/

  • #2
    Re: Thermalite aerocrete blocks for hearth insulation?

    They look good to me...

    But let's see what everyone says.

    I'm still thinking about using lava rocks..

    I took a bunch and made a brick out of lava rocks and cement. Then I let them cure a few days.

    The only test I could think of was putting half of the brick in my gas BBQ. So thats what I did.

    The bbq was over 600 degrees F and the half brick on the inside was hot enough to turn water to steam, but the half brick sticking out was still cool to the touch.

    I think it would work fine! Just don't want to make an insulating error.
    My thread:
    http://www.fornobravo.com/forum/f8/d...ress-2476.html
    My costs:
    http://spreadsheets.google.com/pub?k...Xr0fvgxuh4s7Hw
    My pics:
    http://picasaweb.google.com/dawatsonator

    Comment


    • #3
      Re: Thermalite aerocrete blocks for hearth insulation?

      AAC is made up of sand cement, and aluminum powder, which acts in a chemical reaction to produce the bubbles which create the air spaces which insulate.

      Aerated autoclaved concrete - Wikipedia, the free encyclopedia

      I haven't heard of the product you mention, but I know that fly ash from power plants can be used as a partial substitute for portland in regular concrete.

      If it works, it'll be great. We haven't heard from anyone yet who has used AAC for the oven.
      My geodesic oven project: part 1, part 2

      Comment


      • #4
        Re: Thermalite aerocrete blocks for hearth insulation?

        Well here goes, I'm trying it.



        The blocks were extremely easy to cut to shape with a hand saw, and mortared down just like regular blocks. They do suck a lot of water up though, and I'll be trying to keep them dry from now on to save me an enormous drying session when I first use the oven.



        I've put a thermocouple under the blocks, and will also put one in the heath firebrick, the oven void, the wall etc etc. I'll let you all know how they work out with some real numbers. Fingers crossed they work OK.
        http://fornoeconomico.blogspot.com/

        Comment


        • #5
          Re: Thermalite aerocrete blocks for hearth insulation?

          Great!! I saw these in shop right after I'd poured my vermiculite floor. They'd be a lot easier to get hold of (around here anyway), cheaper, as well as easier and faster to put down. I was thinking of putting them under the floor of my grill (which will sit right beside my oven one of these days...). I'll be really interested to hear how it works out as oven insulation, good for you for trying it!

          Frances
          "Building a Brick oven is the most fun anyone can have by themselves." (Terry Pratchett... slightly amended)

          http://www.fornobravo.com/forum/f8/p...pics-2610.html
          http://www.fornobravo.com/forum/f9/p...nues-2991.html

          Comment


          • #6
            Re: Thermalite aerocrete blocks for hearth insulation?

            I've used AAC as an insulator when I made a charcoal BBQ box once......we have a version of AAC here called Hebel. I found with the heat/cool cycles that it became brittle or developed cracks.

            Carl the thermalite stuff sound interesting though.
            Cheers
            Damon

            Build #1

            Build #2 (Current)

            Comment


            • #7
              Re: Thermalite aerocrete blocks for hearth insulation?

              Carl

              is the material your using water proof, do you think it will hold up well outdoors?

              Thanks

              Rich

              Comment


              • #8
                Re: Thermalite aerocrete blocks for hearth insulation?

                As far as I know it's waterproof - it behaves just like a very lightweight concrete block (which I suppose it is). It soaks water up like a sponge though, so I'm keeping it dry as best I can. The top of my oven will be rendered anyhow, so this bit shouldn't get wet, plus I'll be putting a roof over the whole thing, so I should be OK. (hopefully )

                I don't think I'd want the blocks exposed to the elements in a finished structure, because I'd be worried about the water wicking into the oven. They do make versions of this block that you can use for exterior walls, but I think these are designed for interior walls. You should find more on the link to the manufacturers website.
                http://fornoeconomico.blogspot.com/

                Comment


                • #9
                  Re: Thermalite aerocrete blocks for hearth insulation?

                  I promised to post my results with the AAC block - so here goes. The graph below is after a gentle 3 hour fire, and the 'below hearth insulation' line is the thermocouple that's below the AAC block that's below the hearth bricks. I'm pretty pleased with that - only getting to ~25 degrees above ambient.

                  I'll post more from larger fires when I have them. I also need to make a door to fit the oven - that's why it's cooling so quickly!
                  Attached Files
                  http://fornoeconomico.blogspot.com/

                  Comment

                  Working...
                  X